INTERNATIONAL JOURNAL OF APPLIED ENGINEERING RESEARCH, DINDIGUL Volume 2, No 1, 2011 © Copyright 2010 All rights reserved Integrated Publishing Association RESEARCH ARTICLE
ISSN 09764259
Implementation of Radio Technique in Interstellar Radiation Field for Locating Distant Stars
Bhattacharya.A.B 1 , Tripathi.D.K 1, 2 , Sarkar.A 1 , Bhoumick.A 1 1 Department of Physics, University of Kalyani, Kalyani 741235, West Bengal 2 Department of Physics, Narula Institute of Technology, Kolkata 700109, West Bengal
[email protected]
ABSTRACT An alternative search strategy implementing the method of radio technique may be considered appropriate for locating distant stars in presence of the interstellar radiation field. For the purpose we have taken into account the available data of known stars/constellations up to the recent years to find the required time of reception of the echo radio signals, if transmitted using the wavelengths corresponding to the “water holes” from the earth’s station. It further investigates the probable responding number of stars due to different transmitted power. Keywords: Stars, Interstellar radiation field, Atmospheres, Water holes 1 Introduction It was proposed (Bhattacharya et al., 2009, Bhattacharya et al., 2010) that sky noise windows may be taken as an appropriate alternative search strategy for interstellar communication. For the purpose, the sky noise windows where the hydrogen line and the water line are the two contributors for producing the so called “water holes” can be exploited as an alternative interstellar communication. More specifically, the hydrogen (H) line at 21 cm and the hydroxyl radical (OH) line at 18 cm are combined for producing one water hole between 18 cm and 21 cm while the 2 mm line of start of water molecule extending up to 14 mm line provides a second water hole(Kraus, 1986). In this analysis a good number of Star/Constellation reported up to the recent years (Dixon 1973, Drake 1979, Elliott et al., 2001, Jenkins and Laurance, 2003, Eichler and Beskin, 2004, Greaves et al., 2004, Charbonneau et al., 2005, Deming et al., 2005, Luhman et al., 2005, Butler et al., 2006, Charbonneau et al., 2007, Elliott 2007, Bhattacharya et al., 2010,) with their corresponding distances have been taken into account for calculating the time taken by the radio signal to reach the Star from the Earth as well as the total time taken by the signal to back to the Earth again. The number of probable responding stars at different distances by the varying transmitted power has been critically examined by considering the two “water holes” and applying the standard principle of radio signal transmission (www. space.com/scienceastronomy). 2. Background Most of the SETI radio searches have centred on the water hole. In fact, official strategy of NASA was to search not just the water hole, but the entire microwave window from 1GHz to 10GHz. Some early attempts were there looking at 2,840MHz, which is twice the neutral hydrogen line and some others were at ‘magic frequencies’ such as 4,462MHz which is pi
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INTERNATIONAL JOURNAL OF APPLIED ENGINEERING RESEARCH, DINDIGUL Volume 2, No 1, 2011 © Copyright 2010 All rights reserved Integrated Publishing Association RESEARCH ARTICLE
ISSN 09764259
times of the neutral hydrogen. However, the frequency range between these two emissions, from 1.42 to 1.66 GHz, is a quiet region of the spectrum and is popularly termed as "the water hole" as indicated in Fig. 1. It is well known that the neutral hydrogen gas in interstellar space emits radio signals at 1.42 GHz while the hydroxyl, or OH, emits at about 1.66 GHz. From a consideration of this information of H and OH we find that together they make up the compound of water HOH (i.e. H2O). The frequency range between these two emissions, from 1.42 to 1.64 GHz, is thus a quiet region of the spectrum known as the so called “water hole" (Drake and Helou, 1977).
Figure 1: Interfering noise showing the combination of lowerfrequency galactic noise and higherfrequency noise from our space. The "water hole" exists between the lines for hydrogen (H) and the hydroxyl (OH) ion. The figure reveals that there is a very little noise close to the "water hole." (Drake and Helou, 1977). The 21cm line is formed by an exciting quantum peculiarity in the nature of the electrons within the hydrogen atom. Table 1 provides the outline of the interstellar components and their corresponding states with their fractional volume, density and temperature. 3. Present Approach and Results We have considered quite a good number of reported Star/Constellation (Kraus, 1986) and their corresponding distances for the present investigation as a first step. Using the values of the distances of the stars given in light year (Ly), we have calculated the time taken by the radio signal to reach the concerned Star and also the total time taken by the signal to back to the Earth again.
Table 1: Interstellar medium phases 64
INTERNATIONAL JOURNAL OF APPLIED ENGINEERING RESEARCH, DINDIGUL Volume 2, No 1, 2011 © Copyright 2010 All rights reserved Integrated Publishing Association RESEARCH ARTICLE
Component
Fractional Volume Molecular clouds
