Dense Molecular Clouds in the Galactic Center Region. I. HCN (J = 1--0) Data

Abstract

view Abstract Citations (15) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Dense Molecular Clouds in the Galactic Center Region. I. HCN (J = 1--0) Data Lee, Chang Won Abstract The Galactic center (GC) regions -6° ≤ l ≤ 6° and -0°.8 ≤ b ≤ 0°.87 are surveyed with the HCN J = 1-0 line (88.6 GHz) on a 4' grid with the 14 m telescope at the Taeduk Radio Astronomy Observatory. The data complement the previous 13CO, CS, and H2CO measurements (Bally et al. 1988; Zylka et al. 1992) but cover a wider area with a better or comparable resolution. The asymmetry in emission found in the 13CO observations by Bally et al. (1988) is well confirmed in this study. Interestingly, the asymmetry in HCN emission is more pronounced here: more than 80% of the overall emission is found in the first quadrant (l > 0), and VLSR > 0. Also confirmed is the existence of several emission components in the regions forbidden by the Galactic circular rotation. The HCN maps show a clear absence of more outer Galactic emissions and the 3 kpc arm component, which are both visible in the 13CO map. This implies that the HCN emission lines are not contaminated by foreground or background gas components. Therefore, HCN data are particularly useful in investigating the structures of molecular clouds in the Galactic center. The ΔV (FWHM) values of most of the detected lines are found to be very large, i.e., about 15-55 km s-1 with the mode at ΔV ≍ 25 km s-1 The typical value of ΔV ≍ 25 km s-1 may imply that clouds with mass of an order of 106 Msun are common in the GC region. Another trend found is that the maximum ΔV decreases with l, which may be partly due to the overlapping effects of clouds. Publication: The Astrophysical Journal Supplement Series Pub Date: July 1996 DOI: 10.1086/192309 arXiv: arXiv:astro-ph/9511037 Bibcode: 1996ApJS..105..129L Keywords: GALAXY: CENTER; ISM: CLOUDS; ISM: KINEMATICS AND DYNAMICS; ISM: MOLECULES; Astrophysics E-Print: ApJS submitted, 14 pages with 22 figures, uuencoded, gzipped, tarred postscript files, or available upon request to cwl@sarang.chungnam.ac.kr full text sources arXiv | ADS | data products SIMBAD (1)