An SiO Maser Search off the Galactic Plane

PASJ: Publ. Astron. Soc. Japan 59, 559–587, 2007 June 25 c 2007. Astronomical Society of Japan.

An SiO Maser Search off the Galactic Plane Shuji D EGUCHI,1 Takahiro F UJII,2,3 Yoshifusa I TA,4,5 Hiroshi I MAI,2,3 Hideyuki I ZUMIURA,6 Osamu K AMEYA,7 Noriyuki M ATSUNAGA,4 Atsushi M IYAZAKI,1,7,8 Arihiro M IZUTANI,9,10 Yoshikazu NAKADA,4 Jun-ichi NAKASHIMA,1,11 and Anders W INNBERG1,12 1 Nobeyama

Radio Observatory, National Astronomical Observatory, Minamimaki, Minamisaku, Nagano 384-1305 2 VERA Project Office, National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 3 Faculty of Science, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 4 Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 5 Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510 6 Okayama Astrophysical Observatory, National Astronomical Observatory, Kamogata, Asakuchi, Okayama 719-0232 7 Mizusawa VERA Observatory, National Astronomical Observatory, Mizusawa, Oshu, Iwate 023-0861 8 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030, P.R. China 9 Department of Astronomical Science, The Graduate University for Advanced Studies, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 10 Koriyama City Fureai Science Center, 2-11-1 Ekimae, Koriyama, Fukushima 963-8002 11 Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan 12 Onsala Space Observatory, 439 92 Onsala, Sweden (Received 2006 December 18; accepted 2007 March 27)

Abstract We searched for the SiO J = 1–0, v = 1 and 2 maser lines at 43 GHz in 277 2MASS/MSX/IRAS sources off the Galactic plane (jbj & 3ı ), which resulted in 119 (112 new) detections. Among the new detections, two are very faint objects with MSX 12 m flux densities below 2 Jy. These are likely to be O-rich AGB-stars associated with dwarf-galaxy tidal tails. The sample also includes medium bright MSX objects at moderately high galactic latitudes (3ı < jbj < 5ı ) and in the IRAS gap at higher latitudes. A signature of a warp of the inner Galactic disk is found for a disk subsample. This warp appears relatively strongly in the area of 0ı < l < 45ı and 3ı < jbj < 5ı . We also found a group of stars that does not follow to the Galactic rotation. This feature appears in the Galactic disk at l 27ı , and extends more than 15ı in the galactic latitude, like a stream of tidal debris from a dwarf galaxy. Key words: Galaxy: halo, kinematics and dynamics — masers — stars: AGB and post-AGB

1. Introduction Stellar maser sources are good tracers of Galactic structure. They are mostly AGB (Asymptotic Giant Branch) stars with typical ages of a few Gyr, representing a dynamically well-relaxed component of the Galaxy. Large surveys of maser sources have been made using the OH 1612 MHz line in the past towards objects in the Galactic plane within jlj < 45ı and jbj < 3ı (Sevenster et al. 1997, 2001), or using the 43 GHz (J = 1–0, v = 1 and 2) SiO maser lines toward the Galactic bulge (Izumiura et al. 1995), inner and outer disk (Deguchi et al. 2004a; Jiang et al. 1996), and the Galactic center (Deguchi et al. 2004b; Fujii et al. 2006), or with the 86 GHz (J = 2–1, v =1) SiO maser line in a thinner strip jbj . 1ı (Messineo et al. 2002). However, because of a relative scarcity of sources off the Galactic plane (jbj > 3ı ), all-sky

surveys for the maser sources were not made much in the past (except for te Lintel-Hekkert et al. 1991 or Ita et al. 2001). Because of recent studies of halo sub-structure (Ibata et al. 2001a) and its dynamical influence on the disk structure of the Galaxy (Binney 2001), it is worth looking among SiO maser survey data for signatures of dwarf galaxies in the Galactic halo. In fact, the MSX survey, which was a large deep survey of infrared objects after IRAS, contained data from the Galactic disk (jbj < 6ı ) and additional higher-latitude objects in the limited area that IRAS could not access (the “IRAS gap”). Many of these higher-latitude objects were not searched for masers in the past, simply because they were absent from the IRAS Point Source Catalog, even though they are bright in the infrared. In this paper, we report on the results of SiO maser searches for objects outside the Galactic plane. The sample contains

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very bright to unusually faint infrared sources, because they originate from several observation programs with different rationales. Some of them are very distant objects for which SiO masers were never thought to be detectable, and are therefore interesting in themselves. 2. Observations Simultaneous observations in the SiO J = 1–0, v = 1 and 2 transitions at 42.122 and 42.821 GHz respectively were made with the 45-m radio telescope at Nobeyama, mainly during the winter–spring seasons between 2003–2006; in addition, a few unpublished results from 1999 and 2000 were included in this work. We used a cooled SIS mixer receiver (S40) for the 43 GHz observations and accousto-optical spectrometer arrays, AOS-H and AOS-W, having bandwidths of 40 and 250 MHz, respectively. The effective velocity resolution of the AOS-H spectrometer was 0.3 km s1 . The arrays covered the velocity range of ˙380 km s1 (except for the 2006 observations, which had a ˙150 km s1 coverage), for both the SiO J = 1–0, v = 1 and 2 transitions simultaneously. The overall system temperature was between 200 and 300 K, depending on the weather conditions. The half-power telescope beam width (HPBW) was about 4000. The antenna temperature was corrected for atmospheric and telescope ohmic loss, but not for the beam or aperture efficiency (Ta ). The factor for conversion between the antenna temperature and the flux density is about 2.9 Jy K1 . Further details of SiO maser observations using the Nobeyama 45-m telescope have been described elsewhere (Deguchi et al. 2000a). The objects in the present work originate from several different observing programs, which were partially backup programs during times when the weather was unsuitable for higher frequency observations. Therefore, the results from several different categories of objects are presented here. A majority of our objects are MSX sources off the Galactic plane in the area 0ı < l < 45ı and 3ı < jbj < 6ı ; these objects were mostly excluded from our previous systematic SiO surveys of the Galactic plane, which were limited to a strip with jbj < 3ı (Deguchi et al. 2004a). A second group of objects are mid-infrared (MIR) sources from the jbj > 6ı MSX catalog1 in the IRAS gap; these are often bright MIR objects with no IRAS record, and as a result they have not been thoroughly investigated before. The third group of objects are very faint stars, which were chosen for a search for AGB stars from halo dwarf galaxies. These objects are mostly located at high galactic latitudes; they exhibit star-like red images on 2MASS JHK-band images, but the AGB nature of these objects has not been well established due to their faintness in the infrared bands. These objects were selected by customary color-index criteria for SiO maser searches (Deguchi et al. 2004a): H K > 0:5, and 0:5 . CCE . 0:5. Here CCE = log.FE =FC /, and FC and FE are the MSX flux densities in the C (12 m) and E (21 m) bands. The K magnitude and the 12 m flux density are measures of distance to the source. On average, the mass losing AGB stars at about 8 kpc (as for stars in the Galactic bulge) typically have a color-corrected K magnitude of 6 and 1

Available at hhttp://vizier.u-strasbg.fr/viz-bin/VizieR?-source=V/114i.

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a 12 m flux density of 4 Jy (for objects with an effective dust-shell temperature of 300 K). Therefore, when searching for distant objects, like those of the Sgr dwarf elliptical galaxy (SagDEG) and its tail (D 16–24 kpc), we have to look for faint objects with K & 8 and FC 1 Jy or less. For the case of the CMa dwarf (D 7 kpc), the flux limitation is slightly relaxed. In order to search for SiO masers in such a distant object, we have to observe all of the brighter objects in the same area to get a good idea of the velocity field of foreground Galactic sources. Thus, we included the brighter objects in front of the dwarf galaxies in the survey, especially for the bulge sources toward the SagDEG (center at l = 5ı and b = 14ı ; Majewski et al. 2003). For the case of the CMa dwarf (center at l = 240ı and b = 8ı ; Martin et al. 2004a), it is also problematic because the distance is around 7 kpc and some of the objects spread toward the Galactic disk. For the survey, we chose faint red objects within 30ı of the center of the CMa dwarf. We searched for the SiO J = 1–0, v = 1 and 2 maser lines in 277 objects, and detected 119 (112 new) sources. The detected sources are summarized in table 1 and the undetected sources in table 2. The distribution of the observed sources on the sky is shown in figure 1. Table 3 lists the infrared properties of the observed sources: 2MASS name, 2MASS K magnitude, J –H and H –K color indices, blending flag, MSX 6C name, position difference between 2MASS and MSX sources, MSX C -band (12 m) flux density, CAC = log.FC =FA / where FA is the MSX flux density in the A (8 m) band and CCE = log.FE =FC /, and IRAS name and its separation from the 2MASS position. The 2MASS K magnitude and MSX C -band (12 m) flux density are plotted against the color index of the observed objects in the left and right panels of figure 2, respectively. Though the observed objects involved a wide range of flux densities in terms of 2MASS K or MSX C -band compared with those of other well-defined survey programs, the color indices of the objects were limited to a reasonable range for SiO detections (Deguchi et al. 2000a, 2004b; Fujii et al. 2006). Our sample involved 25 AGB candidates for dwarf galaxy associations, which resulted in 3 SiO detections. We discuss individual objects separately in Appendix and provide 112 spectra of our new detections there. 3. Discussion The observed radial velocities are plotted against the galactic longitude in figure 3. The velocities expected from Galactic rotation are shown by solid and broken curves for various galactocentric distances. The data have been divided into two sub-samples: one “disk sample” with jbj < 10ı and one “high-latitude sample” with jbj > 10ı . There is a hint in the upper panel of figure 3 that the disk sample (open circles) follows the Galactic rotation curve better than the high-latitude sample (filled triangles). Because most of the high-latitude objects are supposedly Galactic bulge stars, deviations of up to about 100 km s1 from the Galactic rotation are to be expected (Izumiura et al. 1995).

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Table 1. SiO detections.

SiO J = 1–0, v = 1 2MASS name

SiO J = 1–0, v = 2

Vpeak Tpeak Flux RMS Vpeak Tpeak Flux RMS Obs. date Vave (km s1 ) (K) (K km s1 ) (K) (km s1 ) (K) (K km s1 ) (K) (yymmdd.d) (km s1 )

J021600092031108 4.1 J03055291+5420538 28.6 J054758683305109 110.8 J062151480350416 7.3 J063531680109256 100.1 J064215300939442 26.4 J064250820141061 17.8 J070727362538440 84.9 J071122170129391 59.8 J071728172417135 59.9 59.1 J072019541320137 J072216341852159 29.0 J074634153218165 26.3 J074940883933293 94.7 J075144403519526 51.3 J081047793520442 72.9 J081442983233047 68.6 J084006910813472 31.7 J090451842810357 86.1 J092206262934129 14.8 J102557510730506 52.0 J10533744+1342544 46.7 J11414026+3828293 56.3 J142809283300034 18.0 J153316521519350 36.0 J153321612711031 9.9 J154631272107395 56.8 J160157273846475 83.9 J160557292747309 46.9 J162035273209370 62.4 J163248542623062 17.5 J163950652406083 9.0 J165212931257016 15.4 J165431100733376 29.3 J170013241037003 42.0 J170306962033255 63.2 J170610811028590 2.1 J171215371637006 43.9 J172728103047542 19.2 J173342462633545 19.6 J173359312659216 260.8 J173651442516262 22.1 J173657572418066 61.8 J173738152557269 58.9 J173942682134239 32.7 J174154582047055 37.3 J174318352109031 30.0 J174410452215239 79.0 J174540352223291 14.3 J174727792058089 22.3 J175323421902545 6.0 J175511281852359 94.3

0.362 0.249 0.114 1.541 1.103 3.954 0.297 1.006 0.270 0.588 0.901 1.042 6.101 1.871 0.286 1.600 0.173 0.660 0.216 0.506 0.904 2.310 0.240 2.364 0.334 1.507 0.717 1.108 0.702 0.881 0.215 0.308 3.034 0.092 4.808 1.866 0.859 0.292 0.315 0.198 0.312 0.398 0.635 0.365 0.172 2.741 0.364 0.268 2.167 0.306 0.162 0.900

0.722 0.387 0.471 5.152 2.336 10.679 0.717 5.406 1.000 1.404 2.773 2.635 43.768 6.505 1.502 2.903 0.692 4.482 0.729 2.065 3.282 8.704 0.225 9.758 0.706 2.299 1.962 2.269 1.093 3.333 0.850 0.626 8.802 0.154 11.724 9.331 2.712 1.321 0.660 0.498 1.312 1.097 1.952 1.557 0.290 12.531 1.254 0.180 7.818 1.230 0.125 3.248

0.072 0.043 0.030 0.053 0.094 0.100 0.060 0.076 0.042 0.083 0.139 0.109 0.076 0.123 0.048 0.149 0.037 0.068 0.061 0.068 0.107 0.099 0.039 0.099 0.066 0.153 0.092 0.132 0.069 0.099 0.047 0.072 0.094 0.038 0.103 0.100 0.082 0.055 0.060 0.049 0.075 0.081 0.076 0.073 0.050 0.107 0.068 0.062 0.130 0.057 0.045 0.106

1.3 28.0 — 7.3 100.7 26.4 18.3 85.1 61.5 59.6 61.4 29.2 31.5 94.7 52.0 72.6 69.0 28.1 91.2 15.0 54.5 45.7 — 18.2 36.2 9.7 — 83.7 47.3 62.7 — 10.2 8.1 32.0 42.0 69.6 1.4 41.7 14.3 20.8 262.2 21.3 62.0 59.3 29.8 25.2 36.0 80.0 14.3 21.9 4.9 92.9

0.950 0.367 — 1.456 0.932 4.503 0.543 0.835 0.276 0.881 1.054 0.945 5.687 1.603 0.278 1.822 0.169 0.605 0.220 0.655 0.403 1.613 — 1.390 0.783 1.920 — 1.815 0.553 0.855 — 0.444 1.481 0.157 10.252 2.493 1.281 0.256 0.163 0.231 0.424 0.562 0.584 0.323 0.247 3.467 0.320 0.300 1.576 0.361 0.246 0.458

1.515 0.424 — 4.861 2.070 10.071 1.128 4.324 0.472 2.618 4.462 2.774 20.633 6.500 1.228 3.224 0.368 3.489 0.505 2.753 0.541 6.075 — 8.593 1.065 4.245 — 2.547 0.921 2.748 — 0.922 7.972 0.647 19.586 13.512 3.382 1.011 0.240 0.305 1.533 1.262 1.611 0.463 0.395 14.630 1.110 0.719 4.830 1.607 0.437 1.286

0.096 0.049 0.039 0.107 0.101 0.123 0.068 0.079 0.049 0.108 0.158 0.114 0.095 0.138 0.062 0.166 0.046 0.089 0.072 0.078 0.100 0.143 0.051 0.128 0.086 0.194 0.106 0.159 0.093 0.131 0.059 0.091 0.121 0.048 0.133 0.135 0.101 0.069 0.078 0.061 0.087 0.100 0.096 0.094 0.065 0.145 0.092 0.080 0.165 0.074 0.057 0.136

030516.5 990516.5 040226.8 000115.9 000407.6 000407.7 000116.9 000116.9 000116.0 000407.7 000115.0 000405.8 000408.8 000117.0 000116.0 000406.7 040115.9 030516.6 000406.8 000408.7 040507.8 040507.8 040510.9 040512.0 050524.9 050524.9 050525.0 040422.1 040421.1 040512.0 050524.0 040518.0 040329.1 040330.3 040329.1 040226.2 040330.2 040418.1 040508.1 050524.0 050529.9 040226.2 050526.0 050528.0 040419.1 040226.2 050526.0 040517.1 040511.0 040419.2 050526.0 050529.0

1.4 28.3 110.8 7.3 100.4 26.4 18.0 85.0 60.7 59.7 60.3 29.1 28.9 94.7 51.7 72.8 68.8 29.9 88.7 14.9 53.2 46.2 56.3 18.1 36.1 9.8 56.8 83.8 47.1 62.6 17.5 9.6 11.7 30.7 42.0 66.4 1.8 42.8 16.7 20.2 261.5 21.7 61.9 59.1 31.3 31.3 33.0 79.5 14.3 22.1 5.4 93.6

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Table 1. (Continued.)


SiO J = 1–0, v = 2


J175557141531531 J175723141802456 J175736051825517 J175936651735346 J180011952947267 J180835012609029 J180851982616210 J181004652559418 J181111482705565 J181214172243588 J181256382434279 J181303402451495 J181355251047054 J181442452355098 J181825050825596 J181836250812320 J181929242302044 J181946272352057 J182020162303504 J182230702041121 J182312582100114 J182528222205007 J182537012153267 J182632030443370 J182645891925293 J182703032014544 J182724750357552 J182726450422462 J182812540417486 J183430990025046 J183501371545026 J183649191351561 J18380663+0229591 J183935851231005 J184252421210401 J184518571010551 J18454730+0527211 J184553421203361 J184753350919102 J184754540821287 J184843901141297 J184951250939299 J18500474+0559286 J18503766+0409088 J185323582620122 J185418400648564 J18542609+1018031 J18551284+1041470 J18590806+1051001 J190123502726106 J190125740529398 J190149861910383

48.2 2.8 29.8 97.8 32.6 7.7 10.6 43.0 5.8 77.0 33.4 1.8 43.2 44.4 12.1 116.1 22.5 41.6 8.0 99.0 71.0 17.6 54.5 86.6 139.0 39.9 15.7 64.2 15.5 63.4 9.8 36.9 95.8 12.1 27.1 15.4 74.1 20.0 49.4 7.6 27.2 7.6 50.5 58.3 46.6 21.0 29.6 51.4 1.5 85.6 88.4 18.8

0.666 1.113 0.530 0.358 1.056 0.236 4.219 2.439 1.076 0.208 0.911 0.411 1.096 0.372 1.807 0.814 0.268 1.138 1.570 1.296 0.580 0.301 0.406 0.557 0.293 0.959 1.266 0.697 0.680 0.477 1.185 1.917 0.530 0.990 1.056 0.616 0.516 0.518 0.442 1.452 0.822 0.711 0.356 0.268 0.717 1.299 0.435 0.414 0.334 0.287 0.884 0.823

2.509 5.881 1.213 0.452 2.793 0.818 20.777 7.600 3.662 0.552 2.723 0.283 3.565 0.851 3.343 2.062 1.271 2.844 3.725 4.522 2.170 1.297 1.698 2.750 0.858 4.801 4.036 2.306 1.922 1.515 4.993 5.108 1.854 3.342 3.907 3.564 0.987 1.158 1.614 3.376 2.838 2.431 0.867 0.227 1.680 3.704 0.511 1.860 1.308 0.882 2.476 2.576

0.080 0.081 0.100 0.070 0.108 0.056 0.122 0.194 0.161 0.045 0.092 0.096 0.100 0.072 0.145 0.124 0.070 0.101 0.115 0.123 0.074 0.059 0.063 0.068 0.061 0.102 0.082 0.094 0.115 0.063 0.144 0.120 0.079 0.127 0.126 0.106 0.151 0.086 0.073 0.129 0.143 0.124 0.069 0.067 0.107 0.095 0.078 0.109 0.077 0.050 0.098 0.105

49.7 2.8 29.7 92.6 32.5 10.2 11.6 42.9 4.9 — 33.9 2.2 43.1 43.9 12.2 116.2 20.4 41.2 9.4 99.1 71.5 22.1 53.0 87.6 139.1 40.1 15.2 62.2 15.3 61.9 9.5 38.3 97.3 9.3 27.0 19.0 74.5 20.5 49.5 7.9 27.5 8.2 50.5 57.3 46.4 20.6 — 55.0 0.5 84.1 87.8 19.0

0.434 1.766 1.496 7.212 0.860 2.028 0.317 0.589 1.389 2.602 0.239 0.598 1.971 12.815 2.365 5.014 1.186 4.205 — — 0.859 2.180 1.319 3.927 0.996 2.751 0.428 0.729 1.700 3.056 1.080 2.207 0.395 0.650 0.776 1.648 0.792 0.890 1.390 4.047 0.491 1.577 0.351 1.009 0.278 1.605 0.486 2.128 0.285 0.971 0.710 3.055 1.411 3.983 0.391 2.019 0.883 1.719 0.504 1.259 1.263 5.950 0.924 3.433 0.295 1.000 0.966 3.010 2.138 6.556 0.550 2.460 0.648 1.272 0.539 1.843 0.677 1.251 1.615 2.256 0.913 1.371 0.874 2.484 0.280 0.346 0.275 0.807 1.015 1.856 0.720 2.899 — — 0.903 2.675 0.452 1.822 0.303 0.827 0.709 1.229 1.012 2.033

0.099 0.106 0.136 0.085 0.140 0.075 0.159 0.231 0.187 0.065 0.119 0.127 0.129 0.095 0.130 0.123 0.088 0.130 0.152 0.121 0.097 0.071 0.071 0.091 0.062 0.102 0.105 0.090 0.113 0.076 0.165 0.154 0.081 0.152 0.161 0.131 0.187 0.106 0.091 0.163 0.173 0.156 0.090 0.080 0.123 0.119 0.079 0.151 0.093 0.061 0.118 0.140

040517.0 040514.1 050529.0 050529.0 040422.2 050530.0 040514.1 050526.1 050529.0 040508.2 040422.2 040423.2 040419.2 050527.1 060421.2 040516.0 050311.2 050311.2 040423.2 060419.2 050311.2 050311.3 050214.4 040514.1 060419.2 060419.2 040514.1 060411.2 060411.3 040517.0 040517.0 040517.1 060411.2 040517.1 040517.1 040517.0 040516.0 040517.1 040420.2 040517.1 040517.1 040517.2 040516.1 040330.4 040420.2 040517.2 060416.3 050529.1 040420.1 040420.2 040420.1 040512.2

48.9 2.8 29.8 95.2 32.5 9.0 11.1 42.9 5.3 77.0 33.6 2.0 43.1 44.1 12.1 116.2 21.4 41.4 8.7 99.1 71.2 19.9 53.7 87.1 139.1 40.0 15.5 63.2 15.4 62.6 9.6 37.6 96.6 10.7 27.0 17.2 74.3 20.3 49.5 7.7 27.3 7.9 50.5 57.8 46.5 20.8 29.6 53.2 0.5 84.8 88.1 18.9

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SiO J = 1–0, v = 2


J190225212037492 J190405490320389 J19061474+0002251 J190859201510032 J191239232341470 J191739391322488 J19221604+0506593 J192222581418050 J192355541302029 J192918401916199 J193021251232535 J193104401640135 J194656440822022 J21582555+6343270 J235844123926599

90.1 39.4 49.3 51.6 62.0 49.8 33.2 74.6 20.7 69.3 140.9 69.5 — 61.9 18.4

0.252 0.608 0.321 0.448 2.532 7.178 0.441 2.522 0.627 1.114 0.866 2.700 0.325 1.630 0.322 1.452 0.124 0.151 0.386 0.721 0.186 0.374 1.494 5.181 — — 2.362 20.436 4.281 10.310

0.045 0.072 0.112 0.068 0.108 0.102 0.073 0.065 0.027 0.078 0.055 0.065 0.045 0.063 0.156

92.7 39.3 49.2 52.4 61.5 49.7 34.3 74.6 25.3 68.4 140.5 69.3 22.0 62.5 18.3

0.181 0.339 2.198 0.357 0.790 0.413 0.543 0.417 0.190 0.465 0.435 1.014 0.269 1.463 4.783

0.653 0.740 6.476 1.495 0.815 1.145 1.348 0.292 0.435 1.447 0.615 2.547 0.512 11.926 9.779

0.061 0.062 0.150 0.090 0.134 0.135 0.099 0.091 0.037 0.107 0.064 0.084 0.065 0.081 0.200

030517.2 060421.2 050530.1 030516.2 030516.2 030516.2 050530.1 040508.2 030517.2 040512.2 030518.2 050214.4 040508.2 040509.3 040508.4

91.4 39.3 49.3 52.0 61.7 49.8 33.7 74.6 23.0 68.8 140.7 69.4 22.0 62.2 18.4

Detected previously by Jiang et al. (1996). Detected previously by Nyman, Hall, and Olofsson (1998). The SiO J = 2–1, v = 1 emission detected previously by Deguchi, Nakashima, and Balasubramanyam (2001). Detected previously by Ita et al. (2001).

Fig. 1. Distribution of the observed sources in the Galactic coordinates in the Hammer–Aitoff’s projection. The dotted curve indicates the orbital plane of the SagDEG.

3.1. AGB Candidates for Dwarf Galaxy Associations The Sgr dwarf elliptical galaxy (SagDEG) was discovered by Ibata, Gilmore, and Irwin (1994) at Vhel = 140 km s1 toward the Galactic bulge. Its distance was estimated to be approximately 24 kpc from the Sun. Later investigations have confirmed the associations of M54 and other globular clusters with this dwarf galaxy, and moreover its associated trail of stars along its orbit being almost perpendicular to the Galactic plane

(Ibata et al. 2001b). The trail included a number of C-rich AGB stars (Ibata et al. 2001a) and M giants (Majewski et al. 2003). Therefore, the idea of looking for O-rich mass-losing AGB stars is not far-fetched, though the low-metal low-mass stars tend to become carbon-rich stars at the AGB phase of stellar evolution (Iben 1981; Ibata et al. 2001b). In fact, an SiO maser source has been detected in the Large Magellanic Cloud with the SEST 15-m telescope at 86.2 GHz (van Loon et al. 1996; see also Wood et al. 1992 for OH/infrared sources).

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[Vol. 59,

Table 2. Negative results.

2MASS name J01015839+5759482 J02005614+0945356 J02151393+5613030 J02300585+4007038 J02311288+6340198 J03133515+5948036 J03230583+5652435 J03275901+6044553 J03404991+4941534 J03482812+1657032 J03552337+1133437 J03563582+5720279 J03591178+4413103 J03595596+0919044 J04432934+3432189 J04501343+3007449 J05233987+3230157 J05301817+2022024 J05434967+3242061 J05481570+2001593 J05514643+3522189 J060925500938492 J061816371702347 J061958211038146 J062043800433270 J062438451753432 J062653901015349 J063428050503427 J063701620127018 J064133910806289 J064408231320089 J064709840358461 J06472497+0813588 J06474716+1636326 J065052510004235 J065139222123303 J065220470328407 J065301490453501 J065517451647526 J065523462122258 J070656851109395 J070749381044059 J071223480124521 J071323172752580 J071323200718336 J071437912513019 J071845752123318 J072439120437541 J072519261121214 J072911202610322 J073212272147136 J073640881018431 J073941812834172

RMS (v = 1) RMS (v = 2) Obs. date (K) (K) (yymmdd.d) 0.053 0.037 0.069 0.039 0.102 0.049 0.043 0.038 0.054 0.030 0.035 0.047 0.048 0.037 0.053 0.062 0.105 0.076 0.110 0.062 0.069 0.067 0.045 0.058 0.066 0.071 0.057 0.063 0.047 0.035 0.045 0.063 0.043 0.052 0.040 0.028 0.042 0.066 0.070 0.033 0.065 0.090 0.044 0.129 0.072 0.024 0.066 0.069 0.032 0.066 0.093 0.046 0.148

0.059 0.027 0.074 0.030 0.213 0.046 0.040 0.031 0.044 0.022 0.027 0.039 0.045 0.027 0.046 0.053 0.086 0.070 0.093 0.056 0.056 0.060 0.041 0.049 0.064 0.069 0.050 0.056 0.039 0.029 0.037 0.058 0.037 0.043 0.035 0.040 0.034 0.053 0.064 0.040 0.063 0.092 0.037 0.132 0.063 0.029 0.058 0.057 0.041 0.058 0.077 0.035 0.131

990515.5 030516.4 990515.5 030516.3 990515.6 990517.5 990517.6 990516.6 990519.5 030517.5 030516.5 990516.6 990517.6 030517.4 990517.6 990517.6 990514.7 990517.7 990514.6 990520.6 990521.6 000116.9 000115.9 000405.7 000114.9 000116.9 000406.6 000405.7 000407.6 000115.9 000408.6 000116.9 990516.6 990521.6 000115.9 040226.8 000408.7 000407.7 000116.9 040113.0 000116.9 000114.9 000405.7 000115.0 000405.8 040226.8 000407.7 000407.7 040112.9 000408.8 000405.8 000408.7 000405.8

2MASS name J074456991541500 J074540921854291 J074545033619503 J074933632546454 J074937263820439 J074957863654299 J075217490329044 J075316831129311 J075540192838544 J075852400122349 J080032353559477 J080049403655221 J080204993811522 J080319183138009 J080430720307483 J081026883914152 J081052443515260 J081210822343485 J081412304142291 J081602883536539 J081918302144143 J082007552616323 J082146791346410 J082211142537546 J082553203333507 J082934883836214 J083338533707051 J083623214057172 J083929314013441 J08451851+1420341 J085958403828491 J090810142819103 J09322353+1146033 J103456030020334 J103519220237477 J104538650441563 J104840560157319 J10484663+0839579 J10505517+0429583 J105236100012060 J10524541+0206444 J10560146+0611076 J11064405+1744146 J11085645+2015280 J11103678+1118057 J11151222+2305439 J11353071+3452042 J11392617+2743564 J11460103+3255584 J11543774+3708068 J12160755+4039367 J12194870+4859028 J13120152+5622487

RMS (v = 1) RMS (v = 2) Obs. date (K) (K) (yymmdd.d) 0.069 0.064 0.101 0.053 0.044 0.150 0.065 0.069 0.125 0.044 0.058 0.167 0.139 0.072 0.064 0.121 0.080 0.061 0.077 0.047 0.062 0.052 0.051 0.077 0.056 0.126 0.057 0.094 0.167 0.039 0.089 0.106 0.037 0.089 0.103 0.070 0.092 0.096 0.052 0.051 0.054 0.094 0.091 0.097 0.097 0.096 0.063 0.039 0.086 0.106 0.047 0.049 0.057

0.073 0.051 0.080 0.045 0.053 0.131 0.048 0.057 0.101 0.058 0.058 0.153 0.133 0.058 0.053 0.117 0.068 0.050 0.072 0.066 0.050 0.041 0.075 0.064 0.048 0.124 0.073 0.083 0.155 0.030 0.076 0.098 0.028 0.061 0.078 0.051 0.074 0.072 0.042 0.041 0.040 0.068 0.064 0.069 0.070 0.068 0.048 0.027 0.068 0.082 0.032 0.035 0.042

000115.0 000406.7 000406.8 000406.7 040114.9 000406.8 030517.6 000406.6 000408.7 040114.8 040114.0 000117.1 000117.1 000408.8 000406.7 000117.0 000406.7 000407.8 000117.0 040226.8 000407.8 000408.7 040226.9 000407.8 000406.8 000117.0 040226.8 000407.8 000117.0 030516.5 000116.0 000405.8 030516.6 040507.8 040510.8 040507.8 040510.8 040507.9 040510.8 040510.9 040510.9 040507.9 040507.9 040507.9 040507.9 040507.9 040510.9 030517.7 040511.0 040511.0 040511.8 040511.8 040508.8

No. 3]

SiO Masers Search off the Galactic Plane Table 2. (Continued.)

2MASS name J13122380+0051472 J13151180+4215593 J133302902317496 J141659351626201 J14572697+0516034 J14573501+6555572 J151325771543595 J15303981+4651311 J153521302356492 J155536942908555 J160623763753547 J160757962040087 J160801763157131 J161418353529559 J163813082834098 J164327281412001 J164624402609490 J16465797+7931489 J170404791128350 J170500652712574 J170552122550378 J172802793039095 J173103322633475 J173859622140226 J180044981700346 J180146092651329 J180356171523263 J181111632630028 J181313851028218 J181830772228418 J182739520349520 J183006051801423 J183250741702485 J18364067+0008011 J184701540228028 J184921530944574 J18492433+0835397 J18495464+0930071 J18530277+0916373 J18550975+0956101 J185753690556101 J185850520259278 J19135861+0007319 J19150117+0348427 J21471812+2532560 J21552697+2342144 J21594957+2356270 J22013668+6259263 J22063830+2458144 J22242842+1453433 J231647602723338 J235053803517479

RMS (v = 1) RMS (v = 2) Obs. date (K) (K) (yymmdd.d) 0.058 0.051 0.059 0.080 0.047 0.063 0.074 0.058 0.068 0.095 0.155 0.043 0.099 0.069 0.095 0.059 0.079 0.041 0.080 0.064 0.082 0.133 0.070 0.057 0.084 0.083 0.118 0.084 0.119 0.107 0.162 0.093 0.068 0.131 0.084 0.129 0.129 0.146 0.086 0.093 0.075 0.156 0.062 0.093 0.065 0.077 0.079 0.072 0.081 0.086 0.046 0.159

0.044 0.037 0.042 0.058 0.034 0.046 0.061 0.041 0.054 0.076 0.122 0.032 0.079 0.086 0.071 0.050 0.095 0.030 0.069 0.052 0.062 0.100 0.053 0.077 0.068 0.062 0.096 0.067 0.096 0.079 0.132 0.092 0.051 0.106 0.064 0.124 0.107 0.119 0.089 0.096 0.064 0.112 0.048 0.074 0.049 0.056 0.059 0.054 0.063 0.067 0.034 0.120

030519.0 040508.8 040507.9 040512.0 040508.9 040508.9 050524.9 040511.9 050524.9 040422.0 040422.1 040508.0 040421.1 040423.1 040515.0 040330.1 040518.0 040511.9 040330.3 050215.2 050213.2 040512.0 050524.0 040226.2 040419.2 040508.1 050529.1 040225.4 040419.2 050529.0 040420.1 060419.2 040225.4 040516.0 040517.1 060411.2 040516.0 040420.1 060411.3 060316.3 060421.2 050529.1 040420.1 040420.1 040509.3 040509.3 040509.3 040509.3 040509.3 040509.4 040508.3 040508.4

565

566

S. Deguchi et al.

[Vol. 59,

Table 3. Infrared properties of the observed sources.

2MASS name

K J H H K Bflag (mag) (mag) (mag)

J01015839+5759482 4.123 J02005614+0945356 7.170 J02151393+5613030 6.014 J021600092031108 2.613 J02300585+4007038 11.701 J02311288+6340198 6.272 J03055291+5420538 4.950 J03133515+5948036 6.217 J03230583+5652435 4.778 J03275901+6044553 5.240 J03404991+4941534 9.057 J03482812+1657032 11.097 J03552337+1133437 11.526 J03563582+5720279 4.389 J03591178+4413103 7.161 J03595596+0919044 10.114 J04432934+3432189 4.816 J04501343+3007449 5.218 J05233987+3230157 4.840 J05301817+2022024 4.728 J05434967+3242061 5.672 J054758683305109 6.152 J05481570+2001593 5.896 J05514643+3522189 7.529 J060925500938492 7.651 J061816371702347 7.986 J061958211038146 3.655 J062043800433270 J062151480350416 5.569 J062438451753432 3.427 J062653901015349 7.633 J063428050503427 5.704 J063531680109256 3.685 J063701620127018 11.289 J064133910806289 6.876 J064215300939442 2.847 J064250820141061 7.017 J064408231320089 6.012 J064709840358461 4.324 J06472497+0813588 5.536 J06474716+1636326 5.823 J065052510004235 2.334 J065139222123303 6.834 J065220470328407 4.260 J065301490453501 0.295 J065517451647526 4.106 J065523462122258 6.576 J070656851109395 10.172 J070727362538440 4.275 J070749381044059 3.651 J071122170129391 3.881 J071223480124521 4.615

0.864 1.741 1.747 0.864 3.039 2.452 1.343 2.739 2.206 2.935 2.547 1.195 1.520 1.189 3.322 1.528 1.218 1.104 1.620 1.060 3.050 0.935 2.477 2.285 1.107 0.445 1.432

0.448 1.355 1.111 0.502 2.745 1.896 0.773 2.119 1.556 2.196 2.307 0.806 1.004 0.715 2.528 1.115 0.666 0.636 0.931 0.576 2.545 0.656 1.889 2.019 1.361 0.611 1.490

111 111 111 111 11 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111

1.769 1.270 1.182 1.270 1.244 1.784 2.407 1.272 3.604 1.226 1.149 2.216 1.854 1.141 1.930 0.861 2.884 1.018 1.837 3.384 0.834 1.650 0.983 0.908

1.400 0.366 1.204 1.235 0.812 3.641 2.019 0.702 2.477 0.732 0.578 1.850 1.546 0.416 1.560 0.472 3.670 0.586 1.454 3.383 0.608 1.240 0.301 0.423

111 111 111 111 111 20 111 111 111 111 111 111 111 111 111 111 11 111 111 11 111 111 111 111

MSX 6C name (124.33204.846) (149.84549.446) (134.43904.771) (198.59369.596) (142.65118.946) G133.7260+02.9110 G141.791703.5248 G139.9388+01.7086 G142.551000.1002 (140.930+03.470) G148.846404.4554 (172.34728.475) (178.18330.959) (145.924+02.982) (154.75406.747) (181.02431.584) (167.73207.460) (172.08009.179) G174.444802.0316 (185.42307.501) G176.5876+01.6391 (238.25826.921) (187.93604.093) (175.145+04.425) (216.89713.672) (224.75114.854) (218.96811.765) (213.5128.902) (212.99708.330) (226.20013.823) (219.37910.067) (215.52106.074) G212.147604.0680 G212.580603.8674 (219.05405.869) (220.52906.412) G213.453302.6799 (224.05207.629) G215.989802.7621 G205.1419+02.8568 (197.674+06.705) G212.932700.1585 (232.17409.528) (216.13101.385) G217.472501.8788 (228.38106.745) (232.53908.736) G224.621201.6745 (237.64608.124) G224.341901.2881 (216.540+03.749) G216.5881+04.0135

∆rM (00 )

1.5 1.3 1.1 2.0 2.5

1.0 1.2

3.1 0.5

2.3 2.0 2.1 1.1

0.2

1.5 1.5 6.9

FC (Jy) 4.3 2.3 7.4 26.7 1.0 6.13 7.60 12.25 20.72 70.4 3.73

CAC

CCE

IRAS name ∆rI (00 )

0.228 00589+5743 0.50 01582+0931 0.040 02117+5559 0.20 021362045 0.16 02269+3953 0.069 0.346 02272+6327 0.003 0.099 03022+5409 0.003 0.198 03096+5936 0.041 0.352 03192+5642 0.275 03238+6034 0.170 0.094 03371+4932

5.1 1.4 2.5 7.1 0.6 3.1 5.7 5.0 1.4 1.3 1.3

7.1 36.3

0.205 03525+5711 2.0 0.087 03557+4404 2.0

3.4 5.9 14.74 5.2 286.90 2.0 15.7 8.0 9.7 3.5 422.0 7.6 86.1 7.0 3.3 51.2 18.80 14.93 13.7 31.5 13.94 2.8 6.37 26.50 5.8 15.29 3.1 2.5 25.35 3.6 3.4 5.42 4.7 94.56 9.2 2.83

0.229 04402+3426 3.2 0.118 04470+3002 3.6 0.082 0.018 05204+3227 6.8 0.172 05273+2019 5.5 0.039 0.288 05405+3240 1.1 0.06 054613306 2.4 0.213 05452+2001 0.3 0.288 05484+3521 2.1 0.039 060700938 6.1 0.152 061601701 3.3 0.034 061761036 11.9 0.155 061820432 0.148 061930349 3.2 0.183 062241751 7.0 0.198 062451013 7.5 0.101 063190501 28.7 0.023 0.022 063290106 3.3 0.175 0.070 063440124 3.5 0.168 063910803 11.8 0.170 063980936 4.6 0.135 0.067 064030138 1.2 0.100 064181317 14.0 0.097 0.119 064460355 1.1 0.063 0.329 06447+0817 11.1 0.298 06448+1639 2.8 0.051 0.114 064830000 7.5 0.52 064952119 3.0 0.123 064980324 5.8 0.041 0.191 065050450 3.2 0.159 065301643 0.8 0.51 065322118 3.0 0.089 0.244 070451104 1.0 0.188 070542533 0.6 0.029 0.107 070541039 4.6 0.198 070880124 4.4 0.126 — 070980119 4.9

No. 3]


567


2MASS name


J071323172752580 8.030 J071323200718336 6.724 J071437912513019 6.335 J071728172417135 5.309 J071845752123318 9.897 J072019541320137 3.534 J072216341852159 6.258 J072439120437541 5.818 J072519261121214 7.055 J072911202610322 4.088 J073212272147136 3.429 J073640881018431 3.797 J073941812834172 5.634 J074456991541500 3.115 J074540921854291 11.511 J074545033619503 — J074634153218165 2.020 J074933632546454 6.930 J074937263820439 9.183 J074940883933293 3.477 J074957863654299 6.898 J075144403519526 4.816 J075217490329044 4.231 J075316831129311 5.768 J075540192838544 2.581 J075852400122349 3.204 J080032353559477 8.045 J080049403655221 5.006 J080204993811522 4.668 J080319183138009 4.441 J080430720307483 5.252 J081026883914152 10.157 J081047793520442 4.242 J081052443515260 4.887 J081210822343485 4.098 J081412304142291 3.782 J081442983233047 8.439 J081602883536539 9.296 J081918302144143 13.441 J082007552616323 4.526 J082146791346410 12.316 J082211142537546 1.284 J082553203333507 3.417 J082934883836214 7.915 J083338533707051 7.026 J083623214057172 9.263 J083929314013441 8.818 J084006910813472 3.839 J08451851+1420341 12.379 J085958403828491 7.108 J090451842810357 4.677 J090810142819103 6.949 J092206262934129 4.231

2.138 1.083 1.566 1.786 3.063 1.791 1.871 1.226 2.729 0.908 1.065 0.868 1.163 0.896 2.587 — 1.046 0.883 2.777 1.029 1.024 1.266 0.815 1.148 0.976 1.142 2.097 1.315 1.135 0.831 1.735 2.409 1.666 1.244 0.810 1.416 2.777 2.632 0.225 0.863 2.564 0.928 1.179 0.146 2.089 3.536 0.993 0.976 1.092 1.826 1.292 1.070 1.309

1.955 0.685 1.265 1.555 2.556 1.190 1.413 0.768 2.208 0.435 0.505 0.450 0.869 0.349 3.229 — 0.595 0.439 2.448 0.717 0.477 0.832 0.546 0.716 0.475 0.413 1.508 0.943 0.664 0.645 1.225 3.266 1.063 0.626 0.577 1.199 2.173 1.969 3.499 0.152 3.665 0.336 0.282 0.364 1.318 3.154 0.691 0.794 0.969 1.215 0.962 1.111 1.125

111 111 111 111 111 111 111 111 111 111 111 111 111 111 11 — 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 1 111 11 111 111 111 111 111 111 111 111 111

MSX 6C name

(240.26407.934) G221.9378+01.5128 (237.99206.484) (237.45605.486) G235.016703.8847 G228.0663+00.2106 G233.171301.9786 (220.869+05.238) (226.894+02.221) (240.37304.024) G236.845001.3185 (227.310+05.170) G243.602503.1359 (233.011+04.294) G235.8880+02.8468 (251.00905.844) G247.586303.6967 G242.2774+00.1587 (253.15106.176) (254.21506.770) (251.93505.398) G250.750604.2919 (223.145+11.853) (230.357+08.143) G245.438100.1478 (222.051+14.305) G252.245403.1055 G253.065003.5430 G254.282604.0008 G248.846200.3074 (224.340+14.695) G256.038803.1799 G252.812900.9980 G252.747600.9362 (243.237+05.603) G258.501203.9346 G250.9283+01.2198 G253.628000.2553 (242.465+08.069) (246.369+05.699) (236.008+12.907) (246.094+06.444) G253.0888+02.5758 G257.6236+00.2459 G256.8978+01.7722 G260.289600.0992 G260.0693+00.8090 (233.675+19.690) (212.266+31.598) (261.218+04.982) (253.986+12.477) (254.583+12.936) 111 (257.642+14.358)

∆rM (00 ) 0.6

2.1 0.8 1.8

1.3 1.0 1.9 – 1.7 2.2

2.8

3.0 1.1 0.7 3.8 0.4 1.8 1.7 0.8 2.5 0.4 1.1

1.9 1.1 0.3 0.4 1.5

FC (Jy) 17.5 2.64 1.6 35.3 3.13 24.51 12.30 5.4 5.1 3.4 13.56 5.4 21.64 19.0 12.06 10.8 136.20 2.22 2.5 26.8 4.7 9.38 5.1 12.7 84.55 9.3 1.64 6.98 32.15 4.94 6.7 29.12 23.79 12.36 10.8 129.20 9.41 1.62 120.0 3.6 3.2 44.8 15.14 1.73 1.65 5.38 1.79 12.8 4.1 12.8 3.8 33.5

CAC

0.044 0.065 0.083 0.056

0.047 0.051 0.108 0.064 0.053

0.048 0.064 0.047 0.035 0.079 0.013 0.099 0.118 0.043 0.133 0.110 0.087

0.031 0.035 0.007 0.071 0.217

CCE

IRAS name

∆rI (00 )

0.182 071132747 2.0 0.100 071090713 3.3 0.75 071252507 19.1 0.128 071532411 5.5 0.192 071662117 4.8 0.046 071801314 1.9 0.022 072001846 5.1 0.093 072210431 17.3 0.14 072291115 11.9 0.111 072712604 7.1 0.132 073002140 1.8 0.184 073431011 2.5 0.049 073762827 3.1 0.145 074261534 1.8 0.114 074341847 1.8 0.145 074393612 6.6 0.167 074463210A 5.7 0.015 074742539 6.8 0.18 074783813 1.8 0.136 074793925 3.7 0.038 074813646 0.8 0.242 074983512 6.6 0.15 074970321 15.1 0.166 075091121 0.9 0.018 075362830 3.2 0.19 075630114 0.2 0.045 075863551 1.6 0.243 075893647 7.5 0.095 080023803 7.1 0.206 080133129 2.6 0.192 080190259 2.1 0.149 080863905 3.0 0.020 080893511 3.0 0.020 080893506 3.0 0.118 081002334 6.0 0.066 081244133 2.5 0.048 081273223 3.4 0.153 081413527 2.6 0.031 081712134 7.1 0.160 081802607 1.1 0.18 081941337 0.4 0.183 082002528 0.9 0.141 082393323 1.4 0.181 082773826 4.1 0.062 083173656 4.2 0.234 083454046 17.4 0.100 083764003 8.9 0.20 083760803 3.0 0.052 0.058 0.174 0.181

085803817 090272758 090602807 091992921

1.2 7.8 3.7

568

S. Deguchi et al.

[Vol. 59,


2MASS name


J09322353+1146033 9.589 J102557510730506 3.364 J103456030020334 3.699 J103519220237477 3.616 J104538650441563 3.897 J104840560157319 1.749 J10484663+0839579 1.706 J10505517+0429583 4.054 J105236100012060 2.730 J10524541+0206444 2.926 J10533744+1342544 1.800 J10560146+0611076 0.762 J11064405+1744146 2.579 J11085645+2015280 1.796 J11103678+1118057 1.581 J11151222+2305439 0.074 J11353071+3452042 0.222 J11392617+2743564 13.036 J11414026+3828293 5.078 J11460103+3255584 3.143 J11543774+3708068 2.700 J12160755+4039367 1.644 J12194870+4859028 1.042 J13120152+5622487 1.853 J13122380+0051472 12.650 J13151180+4215593 2.953 J133302902317496 13.442 J141659351626201 0.568 J142809283300034 5.830 J14572697+0516034 11.438 J14573501+6555572 0.957 J151325771543595 8.573 J15303981+4651311 3.113 J153316521519350 2.580 J153321612711031 2.116 J153521302356492 4.553 J154631272107395 3.831 J155536942908555 3.113 J160157273846475 3.347 J160557292747309 5.320 J160623763753547 2.969 J160757962040087 7.808 J160801763157131 4.659 J161418353529559 4.322 J162035273209370 5.690 J163248542623062 3.649 J163813082834098 3.029 J163950652406083 3.691 J164327281412001 8.645 J164624402609490 7.217 J16465797+7931489 13.927 J165212931257016 1.973

1.167 1.061 1.045 0.918 0.828 0.756 0.997 0.814 0.812 1.015 0.893 0.883 0.808 0.969 0.875 0.851 0.903 1.971 0.696 1.018 0.851 0.896 0.803 0.982 1.939 0.954 1.857 0.961 1.398 1.566 0.883 1.064 0.963 0.930 0.929 0.753 0.841 0.991 0.902 1.102 1.250 1.756 0.900 1.350 1.492 1.087 1.204 1.486 2.967 1.429 1.636 1.187

1.184 0.593 0.409 0.312 0.423 0.233 0.397 0.489 0.271 0.178 0.485 0.313 0.196 0.265 0.296 0.229 0.362 2.047 0.516 0.499 0.474 0.065 0.235 0.592 2.360 0.330 1.100 0.385 1.452 1.238 0.183 1.065 0.486 0.549 0.590 0.518 0.501 0.309 0.985 0.642 0.399 1.497 0.630 0.884 1.102 0.676 0.553 0.828 2.566 1.063 1.276 0.787

111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 11 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111

MSX 6C name (221.069+40.982) G252.1851+40.6053 G247.2370+47.2220 G249.7395+45.7157 G254.4673+46.0008 G252.5530+48.5308 G239.6370+55.6395 G245.8008+53.4319 G251.7823+50.4781 G249.2132+52.1467 G233.0233+59.4269 G245.0506+55.4966 G228.6984+64.1142 G223.7528+65.6028 G241.7906+61.5209 G218.0959+67.8810 G182.7804+72.0228 (206.611+74.026) G170.6827+71.5176 G186.6680+74.7197 G169.5450+74.3872 G148.9833+74.6315 G136.4621+67.3044 G117.1393+60.5156 (314.640+63.257) G106.6951+74.1043 (315.181+38.583) (330.886+41.742) (325.327+25.630) (002.520+52.890) G104.8717+46.5257 (345.966+35.014) G076.0462+53.1519 (350.613+32.178) (341.854+23.195) (344.498+25.403) (348.712+25.792) (344.461+18.506) (338.785+10.485) (347.178+17.924) (340.044+10.548) (352.951+22.576) (344.484+14.632) (342.900+11.185) (346.265+12.601) (352.502+14.521) (351.602+12.188) (355.366+14.776) (004.102+20.200) (354.685+12.323) (112.345+32.139) (006.502+19.204)

∆rM (00 )

FC (Jy)

CAC

CCE


0.8 3.5 3.0 0.8 3.7 1.1 2.1 3.7 1.0 3.3 2.5 1.7 1.5 1.3 1.5 3.0

2.0 12.33 2.95 1.81 1.98 6.18 26.27 0.96 2.36 2.60 34.06 78.61 3.08 5.85 10.27 31.83 145.40

0.084 0.208 0.191 0.099 0.327 0.014 0.217 0.354 0.293 0.014 0.255 0.301 0.245 0.259 0.282 0.066

0.17 09296+1159 4.1 0.216 0.237 — — 104310426 8.9 0.506 0.200 — — 10500+0003 3.5 — 0.322 0.441 0.525 0.386 0.499 0.493 0.276

2.2 1.7 0.8 6.2 2.4 1.6

2.78 2.02 5.99 6.59 10.53 15.13

0.134 0.322 0.125 0.371 0.333 0.122

0.345 11390+3845 9.0 0.215 0.185 0.387 0.480 12173+4915 8.2 0.258 13099+5638 3.8

0.5

4.40

0.193

0.403 13129+4231 3.6

63.5 34.5

0.27 141421612 0.5 0.18 142513246 5.6

0.267

0.468 0.16 — 0.44 0.42 0.34 0.39 0.29 0.27 0.13 0.28 0.18 0.29 0.24 0.13 0.36 0.42 0.39 0.28 0.07

1.2 1.4

85.32 6.1 2.36 15.9 34.3 5.6 6.8 5.4 18.9 6.1 8.0 1.5 8.0 9.9 12.8 16.1 10.1 10.1 25.7 3.4 84.2

—

14567+6607 151061532 15290+4701 153041509 153032700 153232346 154362058 155252900 155863838 160282739 160303745 160502032 160483149 161103522 161733202 162972616 163502828 163682400 164061406 164332604

3.0 4.3 1.3 0.4 3.2 6.5 1.3 8.4 1.5 2.3 8.5 2.9 4.2 1.8 0.5 4.7 7.4 1.8 0.8 8.2

0.28 164941252 1.4

No. 3]


569


2MASS name


J165431100733376 3.008 J170013241037003 3.607 J170306962033255 2.327 J170404791128350 4.483 J170500652712574 4.376 J170552122550378 6.710 J170610811028590 2.485 J171215371637006 5.387 J172728103047542 4.554 J172802793039095 7.553 J173103322633475 10.006 J173342462633545 6.692 J173359312659216 7.963 J173651442516262 5.780 J173657572418066 8.403 J173738152557269 4.366 J173859622140226 2.366 J173942682134239 6.476 J174154582047055 2.787 J174318352109031 5.984 J174410452215239 5.583 J174540352223291 6.192 J174727792058089 4.126 J175323421902545 5.360 J175511281852359 4.132 J175557141531531 4.261 J175723141802456 3.546 J175736051825517 6.836 J175936651735346 9.072 J180011952947267 5.376 J180044981700346 3.827 J180146092651329 6.806 J180356171523263 5.065 J180835012609029 7.711 J180851982616210 2.540 J181004652559418 4.709 J181111482705565 3.231 J181111632630028 2.442 J181214172243588 6.173 J181256382434279 4.023 J181303402451495 2.778 J181313851028218 2.611 J181355251047054 4.318 J181442452355098 4.680 J181825050825596 5.086 J181830772228418 6.296 J181836250812320 6.438 J181929242302044 4.488 J181946272352057 5.798 J182020162303504 5.534 J182230702041121 7.284 J182312582100114 3.665

1.371 1.418 1.243 0.877 0.971 1.511 1.201 1.367 1.450 2.787 2.772 2.697 3.603 2.156 2.066 1.513 1.064 2.737 1.629 1.645 2.269 2.127 1.250 1.650 1.521 1.194 1.198 2.321 1.206 1.850 1.266 2.020 1.251 2.999 2.019 1.206 1.325 1.676 1.679 1.427 1.361 1.359 1.564 1.066 1.507 1.781 2.459 1.082 1.332 1.978 2.980 1.283

0.512 1.023 0.648 0.540 0.733 1.147 0.536 0.896 0.842 1.636 3.133 1.820 2.344 1.273 2.243 0.827 0.434 1.928 0.912 1.181 1.458 1.764 0.874 1.148 0.836 0.783 0.733 1.496 2.331 1.247 0.838 1.305 0.888 1.979 0.935 0.742 0.622 0.595 1.037 0.994 0.684 0.713 0.933 0.701 1.002 1.171 1.600 0.790 1.200 1.515 2.027 0.648

111 111 111 111 111 111 111 111 111 200 11 111 200 111 11 111 111 111 111 111 111 111 111 111 111 111 111 11 11 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111

MSX 6C name (011.601+21.766) (009.710+18.906) (001.632+12.665) (009.508+17.642) (356.418+08.391) (357.652+09.049) (010.677+17.757) (006.219+13.136) G356.3125+02.3153 G356.5031+02.2926 G000.2871+03.9915 G000.6088+03.4930 G000.2854+03.2107 G002.0815+03.5905 G002.9167+04.0899 G001.5967+03.0773 (005.401+05.089) G005.5741+04.9999 G006.5177+04.9771 G006.3750+04.5082 G005.5338+03.7601 G005.5987+03.3939 G007.0341+03.7721 G009.4014+03.5536 G009.7645+03.2730 (012.760+04.789) G010.7465+03.2368 G010.4376+03.0008 G011.4038+03.0029 G000.877203.1703 G012.0459+03.0552 G003.599702.0222 G013.8342+03.1845 G004.963403.0070 G004.887203.1215 G005.262003.2259 G004.410403.9736 G004.937503.6882 G008.363002.0909 G006.821503.1136 G006.579203.2749 G019.2438+03.5743 G019.0495+03.2766 G007.590603.1560 G021.6502+03.4141 G009.276203.2445 G021.8707+03.4771 G008.890103.7045 G008.182804.1522 G008.955803.8905 G011.298303.2262 G011.094103.5183

∆rM (00 )

0.5 3.7 1.5 2.9 2.7 3.5 0.4 4.3 0.2 1.3 1.0 1.0 1.5 2.9 0.5 0.2 3.4 4.3 2.1 1.0 2.1 1.5 2.3 1.1 1.8 0.9 1.3 1.4 0.6 1.3 1.2 0.6 0.4 1.9 4.1 0.4 2.7 1.0 1.8 0.8 2.4 3.8

FC (Jy)

CAC

11.1 89.6 45.5 6.3 7.2 11.8 22.6 10.3 6.32 0.059 4.84 0.069 7.14 0.099 7.45 0.050 7.70 0.084 11.77 0.100 8.56 0.150 7.48 0.043 13.1 13.10 0.023 69.95 0.036 7.52 0.010 13.29 0.077 20.23 0.078 16.45 0.015 7.41 0.044 7.22 0.032 14.6 11.31 0.003 8.44 0.070 7.87 0.056 10.12 0.042 31.42 0.052 5.21 0.061 7.14 0.031 7.50 0.047 80.42 0.006 8.85 0.018 8.63 0.017 19.55 0.061 1.32 0.031 24.58 0.009 23.30 0.049 13.11 0.030 21.94 0.011 7.02 0.031 7.084 0.072 8.07 0.032 13.16 0.098 12.09 0.033 12.21 0.047 48.47 0.042 7.432 0.126 23.74 0.040

CCE


0.28 165180728 1.1 0.24 165741032 1.6 0.16 170012029 5.3 0.22 170131124 4.4 0.37 170182708 3.5 0.10 170272546 4.3 0.22 170341024 3.9 0.13 170931633 7.8 0.294 172423045 4.7 0.018 172483036 23.2 0.036 172792631 2.1 0.160 173052631 11.4 0.034 173082657 1.8 0.054 173372514 1.9 0.086 173392416 4.8 0.343 173452555 2.4 0.28 173592138 6.0 0.057 173672132 8.6 0.014 173892045 13.6 0.097 174032107 15.4 0.053 174112214 22.4 0.042 174262222 2.6 0.287 174442057 22.1 0.075 175041902 2.8 0.221 175221852 6.6 0.27 175301531 2.9 0.179 175441802 4.3 0.131 175461825 6.8 0.006 175661735 14.0 0.085 175702947 2.5 0.084 175781700 2.3 0.019 175862651 7.6 0.155 180101523 3.0 0.001 180542609 3.1 0.201 180572616 4.6 0.168 180692600 4.0 0.377 180802706 8.4 0.275 — 180922244 1.3 0.141 180982435 1.8 0.306 180992452 5.2 0.151 181041029 1.8 0.169 181111048 1.0 0.240 181162356 3.7 0.193 181560827 9.0 0.136 181542229 2.9 0.030 181580813 5.1 0.228 181642303 1.2 0.107 181662353 35.7 0.103 181722305 12.5 0.001 181952042 8.1 0.198 182022101 4.6

570

S. Deguchi et al.

[Vol. 59,


2MASS name


J182528222205007 3.508 J182537012153267 5.235 J182632030443370 5.962 J182645891925293 5.731 J182703032014544 4.744 J182724750357552 4.916 J182726450422462 5.385 J182739520349520 3.041 J182812540417486 4.246 J183006051801423 7.813 J183250741702485 5.310 J183430990025046 5.477 J183501371545026 4.390 J18364067+0008011 6.032 J183649191351561 3.600 J18380663+0229591 5.501 J183935851231005 4.323 J184252421210401 4.826 J184518571010551 4.237 J18454730+0527211 4.496 J184553421203361 5.906 J184701540228028 13.569 J184753350919102 4.028 J184754540821287 3.076 J184843901141297 3.444 J184921530944574 2.884 J18492433+0835397 1.964 J184951250939299 3.244 J18495464+0930071 6.953 J18500474+0559286 5.245 J18503766+0409088 9.973 J18530277+0916373 4.961 J185323582620122 3.235 J185418400648564 3.987 J18542609+1018031 4.968 J18550975+0956101 5.365 J18551284+1041470 2.985 J185753690556101 4.134 J185850520259278 6.587 J18590806+1051001 4.654 J190123502726106 4.449 J190125740529398 4.629 J190149861910383 5.180 J190225212037492 5.086 J190405490320389 3.126 J19061474+0002251 3.619 J190859201510032 5.867 J191239232341470 4.862 J19135861+0007319 4.728 J19150117+0348427 5.650 J191739391322488 4.712

1.378 1.451 2.412 1.691 1.587 2.219 1.791 1.740 1.634 2.318 1.661 2.503 1.561 2.618 1.196 1.735 1.642 1.992 1.580 1.395 2.616 0.957 2.060 1.580 1.458 1.215 1.089 1.581 2.877 2.466 2.659 1.818 1.103 1.152 1.483 1.893 1.276 0.954 3.561 1.777 0.970 1.283 2.230 1.153 1.548 1.308 1.370 1.670 0.373 0.827 1.078

0.705 1.213 1.813 1.217 0.958 1.343 1.227 1.346 1.033 1.727 1.254 1.403 1.026 1.667 0.588 1.079 0.940 1.381 0.847 0.805 1.909 0.534 1.413 0.881 0.800 0.490 0.484 0.757 2.716 1.713 3.454 1.308 0.511 0.826 1.035 1.337 0.661 0.646 2.442 1.118 0.700 0.837 1.445 0.808 0.598 0.715 1.054 1.095 0.270 1.426 0.821

111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111

MSX 6C name G010.378504.4838 G010.565704.4249 G025.8761+03.3593 G012.882303.5242 G012.182103.9649 G026.6530+03.5176 G026.2894+03.3194 G026.8015+03.5262 G026.4509+03.1885 G014.488403.5803 G015.663803.7108 G030.6269+03.5729 G017.058403.5821 G031.3652+03.3445 G018.935803.1069 G033.6401+04.1048 G020.446303.0929 G021.112903.6518 G023.166903.2781 (037.152+03.738) G021.552704.2557 (030.23300.144) G024.225803.4534 G025.086003.0226 G022.197104.7105 G024.005703.9713 (040.365+04.356) G024.142504.0390 G041.2340+04.6520 G038.1146+03.0292 G036.5373+02.0723 G041.3824+03.8617 (009.34112.070) G027.183503.7372 G042.4531+04.0195 G042.2089+03.6940 G042.8937+04.0266 G028.373904.1339 G031.111203.0097 G043.4681+03.2379 (009.05514.146) G029.167204.7190 (016.80410.830) (015.52111.570) G031.391604.3371 G034.658003.2758 (021.23710.662) (013.64414.986) G035.620404.9552 G039.021703.4912 (023.80211.792)

∆rM (00 )

FC (Jy)

CAC

CCE


2.0 14.38 0.001 0.124 182242206 5.5 1.9 22.38 0.009 0.123 182262155 6.0 3.9 15.60 0.041 0.020 182380445 4.4 2.4 7.677 0.011 0.059 182381927 6.1 5.4 8.020 0.056 0.168 182402016 3.8 4.9 19.48 0.030 0.102 182470359 9.8 5.1 8.601 0.006 0.159 182470424 4.3 0.4 124.70 0.054 0.038 182500351 11.7 3.2 7.349 0.056 0.166 182550419 26.2 1.0 7.672 0.039 0.181 182711803 6.2 2.2 27.75 0.362 0.286 182991705 3.5 2.7 12.22 0.083 0.153 183190027 9.3 3.6 17.55 0.038 0.105 183211547 10.8 4.8 9.94 0.071 0.028 18341+0005 4.5 0.5 10.50 0.082 0.268 183391354 8.5 4.1 8.951 0.033 0.087 18355+0227 16.5 1.4 21.92 0.026 0.112 183671233 3.1 2.9 21.59 0.056 0.168 184001213 9.7 0.3 17.79 0.058 0.110 184251014 1.0 14.37 0.172 18433+0524 4.4 2.8 13.72 0.030 0.077 184301206 3.1 14.4 0.17 184430231 50.2 1.0 58.68 0.048 0.137 184500922 51.5 2.3 55.21 0.011 0.119 184510824 2.9 3.6 24.65 0.002 0.222 184591144 3.7 0.4 7.542 0.082 0.336 184660948 7.4 0.37 18470+0832 2.3 16.0 0.2 16.70 0.043 0.331 184710942 27.9 4.6 208.60 0.060 0.272 18475+0926 1.8 0.5 20.15 0.118 0.043 18476+0555 4.9 3.3 5.04 0.146 0.121 18481+0405 6.5 1.7 7.308 0.092 0.012 18506+0912 4.8 11.3 0.07 185022623 4.5 2.0 18.83 0.016 0.301 185160652 3.2 1.8 6.645 0.005 0.035 18520+1014 7.8 2.1 8.881 0.101 0.437 18527+0952 2.3 1.3 12.81 0.046 0.233 18528+1037 5.7 1.6 8.642 0.019 0.039 185520600 0.4 1.5 13.61 0.140 0.087 185620303 5.2 0.9 36.76 0.015 0.121 18567+1046 8.5 10.2 0.17 185822730 1.7 1.0 21.16 0.000 0.210 185870534 7.5 25.6 0.06 185881915 2.9 0.24 185942042 0.5 5.8 1.4 9.612 0.024 0.388 190140325 1.0 1.5 25.27 0.017 0.193 190360002 2.2 8.3 0.11 190611514 4.2 0.09 190962346 2.1 8.3 2.4 25.27 0.705 1.340 19114+0002 1.8 1.8 26.48 0.033 0.070 19125+0343 5.6 9.2 0.20 191481328 5.1

No. 3]


571


2MASS name


J19221604+0506593 3.276 J192222581418050 5.598 J192355541302029 9.747 J192918401916199 4.220 J193021251232535 5.905 J193104401640135 5.054 J194656440822022 5.685 J21471812+2532560 2.912 J21552697+2342144 5.503 J21582555+6343270 3.752 J21594957+2356270 0.408 J22013668+6259263 4.605 J22063830+2458144 2.089 J22242842+1453433 4.067 J231647602723338 11.462 J235053803517479 3.183 J235844123926599 0.165

1.383 1.886 1.946 0.839 1.288 1.405 2.032 1.097 1.915 1.317 1.015 1.012 0.985 0.408 3.529 0.997 0.970

0.690 1.400 1.467 0.570 0.889 1.086 1.633 0.519 1.483 0.938 0.372 0.551 0.419 0.590 2.475 0.391 0.636

111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111

MSX 6C name

∆rM (00 )

FC (Jy)

G041.020904.4857 (023.44913.221) (024.79113.023) (019.46616.779) (025.93114.233) (022.12516.112) (031.66016.112) G078.803121.1479 G078.910523.7599 G105.1364+07.0029 G079.897724.2547 G104.9712+06.2029 G081.924624.4909 G078.119634.8903 G026.741268.9975 G356.903474.7216 G341.255473.5111

1.4

24.45 8.8 1.1 11.9 4.2 24.7 29.8 6.24 7.47 11.56 66.58 2.15 8.15 0.80 0.64 5.67 289.00

1.9 1.3 1.7 1.1 1.3 0.4 0.9 2.5 1.7 1.3

CAC

CCE


0.038 0.107 19198+0501 0.17 191951423 0.26 192111307 0.19 192631922 0.25 192751239 0.11 192811646 0.02 194420829 0.140 0.269 0.068 0.651 0.057 0.375 21570+6329 0.233 0.474 0.064 0.365 22001+6244 0.178 0.336 22043+2443 0.280 — — — 0.062 0.177 0.052 0.187

6.0 3.9 8.5 2.7 0.9 9.2 4.5

4.6 3.0 5.0

indicates IRAS 12 m flux density in column FC and logrithmic ratio of IRAS 25 to 12 m flux-densities in column CCE . No 2MASS object, but the IRAS position is shown.

An enhanced stellar density was found toward the anticenter region in the Sloan Digital Sky Survey (Yanny et al. 2003), suggesting that this is also a remnant of a dwarf galaxy. The center of this enhanced density was estimated to be l = 240ı –244ı , b = 8ı – 10ı , which was named the CMa dwarf galaxy (Bellazzini et al. 2004; Martin et al. 2004b). Because the distance and the radial velocity of the CMa dwarf galaxy are estimated to be 7:2 ˙ 0:3 kpc and 109 ˙ 4 km s1 , respectively (Martin et al. 2004a), our search for SiO masers in this object may be slightly easier than is the case in the SagDEG. We detected three of the 25 surveyed AGB candidates for the dwarf-galaxy associations. The properties of these candidates are summarized in table 4, which gives the candidate group affiliation (Sgr or CMa candidates), radial velocity in the Galactic Standard of Rest VGSR , Λˇ and ˇˇ (the SagDEG coordinates), K and H K, interstellar extinction AK , estimated distance D, IRAS C -band (12 m) flux density F12 , and IRAS name. Here the distance was estimated from the difference between Kc (interstellarand circumstellar-extinction corrected K magnitude) and a standard mK = 6:43 at the Galactic center [K magnitude for Miras without circumstellar extinction with light variation period of 450 d at 8 kpc; see equation (5) of Glass et al. 1995]. Here, the corrected K magnitude, an indicator of distance modulus which is corrected for the interstellar and circumstellar reddening (Fujii et al. 2006), is defined by Kc = K AK =E.H K/ Œ.H K/ .H K/0 ;

(1)

and we use AK =E.H K/ = 1:44 (Nishiyama et al. 2006), and .K H /0 = 0:5 (Fujii et al. 2006). Among the surveyed red objects, it turns out that J14572697+0516034 is a carbon star (Mauron et al. 2005). Since the associations with the dwarf galaxies are not very certain, we discuss the three SiO detected

objects individually: J054758683305109 (IRAS 054613306): This is a faint IRAS source with F12 = 2 Jy. The 2MASS K magnitude is 6.15, suggesting that its distance is about 7 kpc. The high radial velocity relative to the Local Standard of Rest (lsr) (Vlsr = 110 km s1 ) and location in the sky (b = 26ı:9) suggest that this is associated with the CMa dwarf. J081442983233047 (IRAS 081273223): This is a medium-bright MSX source, G250.9283+01.2198, with FC = 9:4 Jy. Its 2MASS counterpart (K = 8:44) has a red H K = 2:17. The interstellar extinction toward this object is quite small (AK 0:2). This object must be an O-rich AGB star undergoing copiously mass-loss. Because of its low galactic latitude (b = 1ı:2) and small radial velocity (Vlsr = 69 km s1 ), this star is probably a disk star. J192355541302029 (IRAS 192111307): This object is a faint (F12 = 1:1 Jy) IRAS source at the edge of the Galactic bulge [(l, b/ = .24ı:8, 13ı:0)]. The 2MASS K magnitude (K = 9:7) suggests that it may be located at a distance more than 18 kpc from the Sun, and could thus be associated with the SagDEG or its tail, though the radial velocity (Vlsr = 23:0 km s1 ) does not fit the velocity of the SagDEG. Figure 4 shows a velocity–longitude diagram in the SagDEG coordinates for SiO sources; the given velocity is based on the Galactic Standard of Rest (GSR) by adopting the maginude of the Galactic rotation, being 220 km s1 , and the longitude (Λˇ ) is measured along the orbital plane of the SagDEG, with the north pole at l = 273ı:8 and b = 13ı:5 (Majewski et al. 2003). By measuring the radial velocities of M giants in the

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Fig. 2. Plots of K versus H K and FC versus CCE . Filled and unfilled circles indicate SiO detection and nondetection.

main trail of the SagDEG, Majewski et al. (2004) showed that the SagDEG objects fall in a narrow strip crossing at Λˇ 65ı with VGSR = 0 km s1 , and that the dispersion of radial velocities of the SagDEG trail is about 10 km s1 . Our candidate star, J192355541302029 (= IRAS 192111307), which is located about 17ı below the Sgr orbital plane, deviates from the expected velocity of the tidal stream of the SagDEG (VGSR 160 km s1 ) at this direction by more than 100 km s1 . However, a numerical simulation of the tidal debris (figure 10 of Law et al. 2005) suggests that the trail of the SagDEG can produce the V 50 km s1 sub-streaming component in this direction; the sub stream is indicated in figure 4 as a thin band between Λˇ 10ı and 150ı at VGSR range between 0 and 180 km s1 . Though the numerical simulations (Ibata et al. 2001b; Helmi & White 2001) have considerable uncertainty in radial velocities of the sub-stream stars, which were torn from the SagDEG in ancient times, the

orbits must cross near the present SagDEG position in any simulations. Therefore, the velocity of VGSR = 67 km s1 at Λˇ = 4ı: 2 does not exclude the possibility of this object being associated with the Sgr dwarf stream. Our observation shows that the radial velocity of J054758683305109, Vlsr = 109 km s1 , coincides with the above-noted velocity of the CMa dwarf (Martin et al. 2004a, 2005). The estimated distance of about 7 kpc for this source (table 4) coincides with the estimated distance of the CMa dwarf. These facts suggest an association of this object to the CMa dwarf galaxy. However, J081442983233047 is unlikely to be associated with the CMa dwarf because of its low radial velocity (68.8 km s1 ) and low galactic latitude (b = 1ı: 2). Even though the association of these objects with dwarf galaxies, or their tails, is somewhat uncertain, they are still O-rich mass-losing AGB stars located far away from the Sun, and as such are interesting objects. Because the progenitors

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Fig. 3. Velocity distribution of the observed sources in the ranges 40ı < l < 50ı (top) and 180ı < l < 270ı (bottom). The solid and broken curves indicate the velocities expected from the Galactic rotation curve, which is assumed to be flat at 220 km s1 or linear within 1 kpc from the Galactic center. One object with the radial velocity Vlsr = 261:5 km s1 (J173359312659216) is out of this figure. The star J05475868 is a candidate for the dwarf galaxy association, and the stars J06353168 and J08144298 are likely disk objects (see subsection 3.1 and Appendix).

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Table 4. Properties of the observed sources for dwarf galaxy member candidates.

2MASS name

Group

J02005614+0945356 J02300585+4007038 J03482812+1657032 J03552337+1133437 J03595596+0919044 J054758683305109 J065139222123303 J065523462122258 J071437912513019 J072519261121214 J074937263820439 J080032353559477 J081442983233047 J081602883536539 J083338533707051 J08451851+1420341 J09322353+1146033 J11392617+2743564 J13122380+0051472 J133302902317496 J14572697+0516034 J160757962040087 J16465797+7931489 J192355541302029 J231647602723338

Sgr Sgr Sgr Sgr Sgr CMa CMa CMa CMa CMa CMa CMa CMa CMa CMa Sgr Sgr Sgr Sgr Sgr Sgr Sgr Sgr Sgr Sgr

SiO VGSR (km s1 )

Λˇ (ı )

109.1 133.0 135.6 134.6 134.5 56:0 138.3 166.9 168.2 173.6 181.0 183.7 190.0 139:1 197.1 197.8 207.0 204.8 217.0 241.1 273.1 290.7 293.7 321.4 216.7 66.9 4.2 56.6

ˇˇ (ı ) 10.1 32.0 3.3 2.2 4.7 54.2 49.1 49.3 54.1 40.9 68.4 66.3 63.0 66.0 67.3 15.8 16.9 6.9 7.0 25.1 10.0 4.6 64.8 16.7 4.7

K H K AK D F12 (mag) (mag) (mag) (kpc) (Jy) 7.170 11.701 11.097 11.526 10.114 6.152 6.834 6.576 6.335 7.055 9.183 8.045 8.439 9.296 7.026 12.379 9.589 13.036 12.650 13.442 11.438 7.808 13.927 9.747 11.462

1.355 2.745 0.806 1.004 1.115 0.656 1.560 1.454 1.265 2.208 2.448 1.508 2.173 1.969 1.318 0.969 1.184 2.047 2.360 1.100 1.238 1.497 1.276 1.467 2.475

0.025 0.021 0.116 0.088 0.101 0.012 0.108 0.119 0.160 0.208 0.230 0.851 0.203 2.185 0.263 0.009 0.008 0.009 0.013 0.037 0.015 0.128 0.016 0.065 0.010

7 20 > 30 > 30 29 7 5 5 5 4 8 9 7 10 6 > 30 21 > 30 > 30 > 30 > 30 8 > 30 19 22

IRAS name

2.3 01582+0931 1.0 02269+3953

2.0 3.1 3.4 1.6 5.1 2.5 1.6 9.4 1.6 1.7

054613306 064952119 065322118 071252507 072291115 074783813 075863551 081273223 081413527 083173656

2.0

09296+1159

1.5

C star 160502032

1.1

192111307

P–M relation, mK = 6:43 at 8 kpc for P = 450 d, was used. From Mauron, Kendall, and Gigoyan (2005).

of O-rich AGB stars are considered to be more massive than those of C-rich AGB stars, their presence in dwarf galaxies would constrain chemical-evolution and pollution models of dwarf galaxies (e.g., McWilliam & Smecker-Hane 2005). 3.2. A Warp Signature for the Off-Plane Objects It is interesting to check whether the velocity distribution of the off-plane objects (3ı < jbj < 5ı ) exhibits any differences from the lower-latitude (jbj < 3ı ) velocity distribution. The upper panel of figure 5 shows a comparison of the velocity distribution between the “on-plane” (lower latitude) and the off-plane samples: one from the SiO maser data with jbj < 3ı and 0ı < l < 45ı (Deguchi et al. 2004a), and the other with 3ı < jbj < 5ı and 0ı < l < 45ı (from the present paper). For the purpose of making the distance cut off as similar as possible for both samples, we chose 127 stars with FC > 6:5 Jy within an area of 0ı < l < 45ı and jbj < 3ı for the on-plane sample. At first glance, this diagram gives the impression that the off-plane sample contains a smaller number of objects with Vlsr > 100 km s1 , as compared with those in the on-plane sample. The average of Vlsr for the off-plane sample (63 points) is 19.1 (˙60:1) km s1 , while the average of Vlsr for the on-plane sample (127 points) is 40.6 (˙59:8) km s1 . This difference of the velocity field between the upper and lower disk samples is valid, because the disk scale height is about

300 pc ( 3ı at 6 kpc); the off-plane sample (jbj > 3ı ) does not contain many distant disk objects above the disk scale height. We conducted a two-dimensional Kolmogorov–Smirnov (K–S) test (Fasano & Franceschini 1987) for the upper and lower disk samples [for algorithm for the two-sample test, see subsection 14.7 of Press et al. (1992)]. We found that the null hypothesis of the distribution in the longitude–velocity plane for the off-plane sample being the same as the distribution of the on-plane sample has a probability of less than 0.1%. Therefore, the conjecture that the off- and on-plane samples have different velocity distributions is verified with a 99.9% confidence level. The largest difference in the fraction between the two samples is 0.386; this occurs in the upper-left quadrant at the point .l; Vlsr / =(13ı.7, 30.9 km s1 ), which is indicated by a cross in the upper panel of figure 5. Most of the objects on the right side of this point (l < 14ı ) supposedly belong to the Galactic bulge, where the velocity field is different from that of the disk objects. Most of the objects in the left portion (l > 14ı ) are expected to be disk sources. A lack of high-velocity objects in the off-plane sample appears more strongly for the subsample of the b < 3ı , l > 14ı objects. The lower panel of figure 5 shows a comparison between the velocity distributions of objects with b < 3ı and b > 3ı . Above l = 14ı , only one object in the b < 3ı subsample has Vlsr > 50 km s1 , while there are 6 objects

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Fig. 4. Velocity distribution of the SiO maser sources in the SagDEG coordinates. Blue diamonds indicate the SiO maser sources detected in this paper, and the large filled red circle indicates the candidate for SagDEG tidal-tail associations, J19235541302029. Black squares indicate the M giants sampled by Majewski et al. (2004) and the thin broad bands are result of simulation of the tidal tail of the SagDEG, which were taken from Law et al. (2005).

Table 5. The values of the best parameters of the warp from SiO maser data.

Sample Disk only (jbj < 3ı ) Whole (jbj < 5ı ) Velocity limited (jbj < 5ı with Vlsr > 50 km s1 ) in the b > 3ı subsample with such velocities (though the two-dimensional K–S test for these sets does not give any statistical significance due to the small numbers). This asymmetry with respect to the galactic latitude for the off-plane objects can be attributed to the warp of the Galactic disk. Because the warped disk plane is shifted toward positive b in 0ı . l . 180ı, a shift of the warped disk plane of less than a degree would considerably influence the cut off of the distant objects in off-plane subsamples. Though, in general, the disk warp is considered to appear more strongly for the outer disk samples (Djorgovski & Sosin 1989), it also appears in inner disk samples [for example, see the case for MSX point sources by Vig et al. (2005)]. Figure 6 shows the distribution of sources in the Galactic coordinates and the regression curves for several subsamples. Apparently, in order to obtain the better regression-curve fit, the sample involving distant objects with a higher jbj is preferable, so that the upper disk sample in this paper is quite useful to limit the warp parameters. Table 5 lists the bet-fit parameters for three different samples: the on-plane sample (jbj < 3ı ), the whole sample (jbj < 5ı ), and

Data points

b0 (ı )

0 (ı )

R

79 108 48

0.50 (˙1:16) 3.09 (˙1:62) 2.23 (˙2:27)

25.6 (˙17:5) 28.4 (˙4:0) 19.8 (˙10:1)

0.049 0.182 0.141

the high-velocity (Vlsr > 50 km s1 ) sample. Both the sense of the inclination (b0 2ı ) and the shift in the azimuthal angle (0 20ı ) of the warp plane match to those obtained by Vig et al. (2005) analyzing the inner-disk MSX PSC sources. An alternative explanation of this asymmetric star distribution (especially for the nearby star concentration around l 23ı and b 4ı ) could be accretion of a dwarf galaxy debris by the Galaxy. However, the high stellar density of this asymmetric star group in the inner disk virtually excludes such a possibility, though in general it may be hard to distinguish such accretion process from the effect of warp in the outer disk at low star density [for example, arguments in Momany et al. (2006) for the case of CMa over-density]. 3.3. A Group of Stars with Unusual Velocities: a Star Stream We noticed a concentration of three stars with Vlsr < 50 km s1 in a small area in figure 3 upper panel (indicated by filled triangles at the lower left): J192222581418050 (74.6 km s1 ), J192918401916199 (68.8 km s1 ), and J193104401640135 (69.4 km s1 ). They are concentrated

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Table 6. Properties of maser sources with Vlsr < 50 km s1 .

IRAS name

Other name

l (ı )

b (ı )

18307+0102 183250721 183870951 183931020 183990149 184650717 191951423 192631922 192811646

OH031.8+04.5 OH024.581+00.224

31.817 24.581 23.078 22.707 30.336 26.246 23.448 19.466 22.122

4.537 0.224 2.274 2.631 1.171 2.814 13.220 16.779 16.110

OH022.70702.631 OH030.336+01.171 OH026.24602.814

Vlsr km s1 62.8 72.6 62:8 76.1 64.7 65.8 75.3# 68.8# 75.2#

K (mag)

H K (mag)

Kc (mag)

F12 (Jy)

C12

6.902 — 12.215 6.934 4.607 7.886 5.598 4.220 5.054

1.561 — 1.075 1.400 0.899 2.876 1.400 0.570 1.086

5.374 — 11.387 5.638 4.032 4.465 4.302 4.119 4.210

6.4 5.3 7.0 5.9 12.1 16:4k 8.8 11.9 24.7

0.111 0.340 0.299 0.070 0.134 0:010k 0.170 0.190 0.110

Eder, Lewis, and Terzian 1988. Sevenster et al. 2001. Not identified in 2MASS database, but seen on the Spitzer GLIMPSE image; see Deguchi et al. 2007. te Lintel-Hekkert et al. 1991. k Apparent double sources; flux densities not reliable (Deguchi et al. 1999). # Present work.

within a few degrees at .l, b/ .21ı:7; 15ı:4/. This is quite unusual, because the Galactic rotation at this longitude should give a positive Vlsr for most of the objects (except for stars located very far beyond 15 kpc). Because these objects are medium-bright sources (FC = 8–24 Jy and K = 4:2–5.5), their distances are estimated to be less than 7 kpc. We also noticed that some disk maser sources (jbj < 3ı ) occasionally exhibit similarly large negative velocities in the area 15ı < l < 30ı ; for example, see the SiO and OH l–v diagrams (figure 4) given by Deguchi et al. (2004a). In table 6, we list the infrared properties of these objects with radial velocities of less than 50 km s1 , located in 19ı < l < 32ı , giving the IRAS name, the alternative name, the Galactic coordinates, Vlsr , 2MASS K magnitude, H K, corrected K magnitude Kc , IRAS 12 m flux density F12 , and the IRAS color C12 Œ= log.F25 =F12 /. The positions of these objects are plotted in the Galactic coordinates in figure 7. But the CO l–v diagram does not show any feature associated with these velocities in this longitude range (Dame et al. 2001; Kawamura et al. 1999), although there is a distant spiral arm feature spreading at higher velocities [from ( 20ı , 0 km s1 ) to ( 40ı , 50 km s1 )] (due to the 15 kpc arm). We also do not find any negative-velocity SiO maser sources with Vlsr < 50 km s1 up to the longitude l = 50ı , where distant objects obeying the Galactic rotation start to show negative Vlsr (for example see figure 8 of Nakashima & Deguchi 2003). Note that the radial velocities of these stars, if the motion of the Local Standard of Rest (220 km s1 ) about the Galactic center is subtracted (i.e., velocities in the GSR), are quite small ( 20 km s1 ), suggesting that they are moving perpendicularly to the line of sight at a high speed. The origin of this negative velocity group is not clear. We have several conjectures. One is that they are a part of the radial outward stellar motion, which is produced by the dynamical effect of the bulge bar. According to an analysis of Hipparcos data made by Feast and Whitelock (2000), a stream of short-period Mira stars is observed at negative velocities ( 75 km s1 ) toward the bulge, and some of these extend

beyond the solar circle. The negative-velocity streaming of these stars spreads on a large scale toward the bulge. The feature that we observe, especially around l 30ı , might be a part of this large-scale outward star flow; the concentration around .l, b/ .22ı , 15ı / may be a stochastic effect. An alternative conjecture is that the velocity structure is a manifestation of a star stream crossing in the Galactic disk (for example, see Navarro et al. 2004). The broken line in figure 7 indicates a linear least-squares fit to the positions of the negative-velocity objects. We found that this regression line passes within 0ı: 1 of NGC 6712. This globular cluster has Vlsr = 92 km s1 (Harris 1996), which is close to the average velocity of these objects (69:3 km s1 ) if the uncertainty of the optical radial velocity measurements of globular-cluster members (of about 20 km s1 ) is factored in (Matsunaga et al. 2005). The other 2 nearby globular clusters have somewhat similar radial velocities (Vlsr = 53:9 km s1 and 44:9 km s1 for Pal 11 and NGC 6749, respectively) except for NGC 6760 (Vlsr = 10:9 km s1 ). It is possible that these globular clusters are fossil remnants of the same dwarf galaxy plunging into the dense inner disk of the Galaxy. In fact, de Marchi et al. (1999) found evidence of a tidal disruption of NGC 6712. Paltrinieri et al. (2001) found about one hundred blue stragglers in the same globular cluster. In the core of globular clusters, it is possible to generate the antecedents of AGB stars by main-sequence mergers (Matsunaga et al. 2005; Andronov et al. 2006), and later they can escape out from the original globular cluster by tidal interactions. Because primordial low-mass metal-poor stars in aged globular clusters (M < 1Mˇ ) cannot be evolved to SiO maser stars with large mass-loss rates at the AGB phase, only larger mass stars, such as merger antecedents, can be sources of maser stars in globular clusters or dwarf galaxies. Although, at present, we do not have any other strong evidence for the existence of the dwarf galaxy, or its tidal tail in this direction, the presence of a star stream remains to be an interesting speculation.

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Fig. 5. Comparison of velocity distributions for objects above and below jbj = 3ı (top), and another comparison for upper disk objects with b > 3ı and b < 3ı (bottom). All the objects plotted have jbj < 6ı . The cross in the top panel indicates the position of the most significant difference in fraction between two samples from a 2-d Kolmogorov–Smirnov test.

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Fig. 6. Source distribution in Galactic coordinates. The small and large open circles indicate the disk sample (jbj < 3ı ) and whole sample (jbj < 5ı ). Filled circles indicates a subsample of distant objects (Vlsr > 50 km s1 ). There is a concentration of 4 sources within 1ı at (26ı. 3, 3ı. 3), but this seems a chance coincidence, because their radial velocities are very diverse from 15 to 86 km s1 . The thin ellipse at the lower right part indicates a concentration of relatively nearby stars asymmetric with respect to the Galactic plane. The best-fit linear line for each sample [minimizing square sum of residue yi = bi b0 sin.li 0 /, .i = 1; :::; n/] is shown.

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Fig. 7. Distribution of SiO/OH maser sources with Vlsr < 50 km s1 (filled circles). Positions of the nearby Globular clusters are indicated by open squares; data are taken from Harris (1996) except GLIMPSE C01 (Kobulnicky et al. 2005). The broken line indicates the least squares fit to the galactic coordinates of maser sources: l = 0:39 .˙0:11/ b + 27ı: 0 .˙1ı: 1/, where the values between parentheses are standard errors of the coefficients.

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Fig. 8. (a) Spectra of new SiO detections. The previous detections are not shown. The 2MASS name (first half) and observed date (yymmdd.d) are shown on the upper left in each panel.

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Fig. 8. (g) (Continued.)

4. Summary We surveyed 277 2MASS/MSX or IRAS sources off the Galactic plane, and obtained more than one hundred new detections in the SiO maser lines. Two of these SiO sources are associated with very faint infrared objects, and are likely to be associated with the Sgr or CMa dwarf galaxies. We also found a clear signature of a warp of the Galactic disk in the off-plane (jbj > 3ı ) sample. Furthermore, we found an interesting group of O-rich AGB stars at .l, b/ .22ı ; 15ı /, which did not follow the Galactic rotation. This may suggest the presence of a stream of stars penetrating the Galactic disk, whose origin is not clear. The authors thank Dr. B. M. Lewis for the useful comments and kind advice on English. One of the authors (A.W.) aknowledges National Astronomical Observatory of Japan for approving him to receive a short-term visiting fellowship in 2003. This research made use of the SIMBAD and VizieR databases operated at CDS, Strasbourg, France, as well as the use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and National Science foundation, and from the Midcourse Space Experiment at NASA/ IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Appendix. Individual Objects The SiO maser spectra for the newly detected objects are shown in figures 8a–g. We discuss here interesting objects individually: J063531680109256 (IRAS 063290106): This object has a radial velocity 100.4 km s1 at l = 212ı, which is considerably large if compared with the Galactic rotational velocity (see the lower panel of figure 3). The SiO masers were detected first by Jiang et al. (1996). This object is a bright infrared source (K = 3:7 and F12 = 18:8 Jy) with IRAS LRS class 29 (silicate emission; Olnon et al. 1986), suggesting a distance of a few kpc. It is unlikely that this is associated with the CMa dwarf or its tail. J175723141802456 (IRAS 175441802): This object

is denoted as LDN 292, a dark Nebula, in the SIMBAD database. However, the detection of SiO masers secures this object as an AGB star, which is consistent with its IRAS LRS class of 29 (silicate emission). The 2MASS images exhibit a faint nebulosity of size of about 3000 toward this bright (K = 3:546) object. J170013241037003 (IRAS 165741032 = V 2207 Oph = IRC 10355): This is a strong IRAS source with F12 = 89:6 Jy and LRS class of 28 (silicate emission). Previous searches for OH 1612 MHz and H2 O 22 GHz emission were negative (te Lintel-Hekkert et al. 1991; Lewis 1997). Nyman et al. (1992) included this object in the list of tentative detections by the CO J = 1–0 line, but the radial velocity was not given. Near-infrared (NIR) light variations have been detected (Lockwood 1985). The detection of strong SiO masers at Vlsr = 42:0 km s1 confirms that this is a mass-losing AGB star. J173359312659216 (IRAS 173082657): This object has a large negative radial velocity of 261 km s1 . Its position [.l, b/ = .0ı:3; +3ı:2/] and the infrared flux densities (FC = 7:7 Jy and K = 7:9) indicate that this is a star in the Galactic bulge. Large negative radial velocities are common for bulge stars in the x1 orbit family (Fujii et al. 2006). J174154582047055 (IRAS 173892045): This is a strong infrared source with F12 = 66:0 Jy and LRS class of 28 (silicate emission). OH 1612 MHz and 1665/67 MHz lines have been detected (Le Squeren et al. 1992; David et al. 1993) at Vlsr = 13:8 and 47.5 km s1 , the mean velocity being consistent with SiO detection at Vlsr = 31:3 km s1 . This object was included in a relatively small number of the AGB stars sampled by IRTS; from infrared spectra between 1–5 m, the distance was estimated to be about 1 kpc (Le Bertre et al. 2001). J180851982616210 (IRAS 180572616): This is a strong infrared source with F12 = 59 Jy with LRS class of 26 (silicate emission). An OH 1612 MHz maser was detected at Vlsr = 7:7 and 29.7 km s1 (te Lintel-Hekkert et al. 1991), the mean velocity being consistent with the SiO radial velocity of 11.1 km s1 . J235844123926599 (= RR Phe) : Though it is a well-known optical/NIR variable star with a period of 427 d (Jura et al. 1993), located close to the South Galactic pole (b = 73ı:5), it was not recorded in

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FC = 289 Jy. We detected relatively strong SiO maser emission at Vlsr = 18 km s1 . No previous OH or H2 O maser observation was found for this star.

the IRAS catalog because of its position in the IRAS gap, and had been neglected. The MSX out-of-plane survey found this object to be a strong MIR source with

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