Astron. Astrophys. Suppl. Ser. 138, 187-202

Galactic anticenter CO survey

I. Area $l=178^\circ$ to $186^{\circ}$, ${\it b}=3\hbox{$.\!\!^\circ$}5$ to $6^{\circ}$

Y. Lee - J.H. Jung - H.S. Chung - H.-G. Kim - Y.-S. Park - H.R. Kim - B.-G. Kim - J. Kim - S.-T. Han

Send offprint request: Y. Lee (ylee@cfa.harvard.edu), visiting scientist at Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138, U.S.A.

Korea Astronomy Observatory, Taeduk Radio Astronomy Observatory, San 36-1 Hwaam-dong, Yusung-gu, Taejon
305-348, Korea
e-mail: yulee@hae.issa.re.kr

Received July 2, 1998; accepted April 09, 1999

Abstract:

We have mapped a 17 square-degree section (l, b) = ($178\hbox{$.\!\!^\circ$}0 \sim 186\hbox{$.\!\!^\circ$}0,\ 3\hbox{$.\!\!^\circ$}5 \sim 6\hbox{$.\!\!^\circ$}0$) of the Galactic Anticenter region in the ¹²CO J=1-0 line using the 3-mm SIS receiver on the 14-m telescope at the Taeduk Radio Astronomy Observatory. A total of 7 000 spectra has been obtained with a grid spacing of 3'. The results of the observations are presented in the form of l-b and v-b contour maps. Molecular emission of the mapped area is found to be very extended and matches with the FIR emission boundary. The radial velocity of the molecular gas is found to be within the range of $v_{\rm LSR}=-25\sim$ +10 km s^-1. We also found several small clouds located at $l = 180^{\circ}$, $b=5^{\circ} \sim 6^{\circ}$ having $v_{\rm LSR}=-20$ km s^-1, which is quite anomalous in this direction. We identified 30 individual clouds within the mapped region with an arbitrary threshold temperature using a cloud identification code. Twelve subclouds were also identified from the largest cloud with a higher threshold temperature. The ratio of dust emission to CO integrated intensity for the Galactic Anticenter region is found to be similar to that of the dark clouds in solar neighborhood, and much less than that of giant molecular clouds, implying that the heating source within the clouds is minimal.

Key words: ISM: clouds -- ISM: abundance -- ISM: dust -- ISM: HII regions