The L1457 Molecular/Atomic Cloud Complex: H i and CO Maps
G. H. Moriarty-Schieven, B. G. Andersson, P. G. Wannier;
ApJ, 1997, 475, 642
ABSTRACT:L1457 is the closest known molecular cloud (65 pc), and it lies near the edge of the local hot bubble and well out of the Galactic plane (b ~ -34
deg).
We have mapped an 8 deg x 8 deg region at 35' resolution and a 3 deg x 5 deg
region at ~2' resolution in H I 21 cm emission.
We have also mapped a 2 deg x 4 deg
region at 2' resolution in 12CO J = 1--0.
We find that there is an extended
component of atomic gas, clearly associated with the molecular complex and
comparable to it in total mass.
The H I structure at small scales in the vicinity of
the molecular clouds is remarkable, consisting largely of long, narrow
filaments less than 20' (0.2 pc) in width and 1 deg--4 deg in length.
A thin (<10')
limb-brightened atomic halo is seen to surround the CO at some velocities, but it is
ill-defined at other velocities.
The halo may be disturbed by external pressure,
perhaps from the hot gas in the local bubble.
The molecular clouds are part of a
large structure ~5 deg x 3 deg in extent with a small "funnel-shaped"
extension to the south.
The structure, which we call the L1457 atomic/molecular
complex, is dominated by H I in the north and H2 in the south extension.
Roughly
one-half the mass of the complex is molecular.
The structure of this complex at
both large- and small-scale suggests that the south end has been recently
compressed.
KEYWORDS: ism: individual alphanumeric: l1457, ism: molecules, ism: structure, radio lines: ism
CODE: moriarty-schieven97