A HIGH VELOCITY MOLECULAR CLOUD NEAR THE CENTER OF THE GALAXY
Tomoharu Oka(1), Glenn J. White(2), Tetsuo Hasegawa(3), Fumio Sato(4), Masato Tsuboi(5), and Atsushi Miyazaki(5)
(1) size The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
(2) size Physics Department, Queen Mary & Westfield College, University of London, Mile End Road, London E1 4NS, U.K.
(3) size Institute of Astronomy, Faculty of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan.
(4) size Department of Astronomy and Earth Sciences, Tokyo Gakugei University, 4-1-1 Nukui-kita, Koganei, Tokyo 184-8501, Japan.=
(5) size Institute of Astrophysics and Planetary Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan.
Paper: to appear in ApJ
Abstract:
We report the detection of a peculiar molecular cloud, CO 0.02-0.02, lying
about 5' Galactic-east from the center of the Galaxy. 12CO
images taken with NRO 45 m telescope showed that it is relatively compact
( ~\!3* 4 pc2) as well as having a very large velocity width
( DELTA V\!>=\!100 km s-1). The cloud has a virial mass about one
order of magnitude larger than the LTE mass, 9* 104 M_\sun,
indicating the cloud is apparently gravitationally unbound.
New observations with the JCMT 15 m and the NRO 45 m telescope show that CO
0.02-0.02 is very bright in the CO J=3D3-2, and in the HCN and
HCO^+ J=3D1-0 lines. It appears that the environment may have an
unusually high density and temperature,
which may be related to the very broad CO line-width. We propose that CO
0.02-0.02 may have been accelerated, heated and compressed in a series of
supernovae shocks which have occurred within the last (3-5)*
104 years.
Preprints available from the authors at oka@postman.riken.go.jp=20
,
or the raw TeX (no figures) if you click here.
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