Astronomy and Astrophysics – Astrophysics
Scientific paper
Jul 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997a%26a...323..931w&link_type=abstract
Astronomy and Astrophysics, v.323, p.931-942
Astronomy and Astrophysics
Astrophysics
20
Stars: Formation, Ism: Individual: Rosette Nebula, Shocks, Ism: Molecules, Radio Lines: Ism
Scientific paper
Molecular line observations are reported of two regions containing small cometary globules at the edge of the Rosette Nebula. Observations of the CO, 3CO and C^18^O J=21,-and CO J=43-molecular lines towards Globule 1, the most prominent of the group, show it has a well-developed head-tail structure, with a head diameter ~0.4pc, and a tail extending ~1.3pc behind it. The major axis of the system points about 45 degrees away from the direction to the centre of the Rosette Nebula (which contains the [presumed] illuminating stars), and 20 degrees out of the plane of the sky, along a projected line towards the luminous (924Lsun_) infrared source IRAS 06314+0427. The CO lines have a complex velocity structure; with a pronounced broadening at the front of the head (as viewed from IRAS 06314+0427); a velocity gradient ~1.4km/s along the tail, and material at the front of the head is blue-shifted by ~0.5km/s compared to surrounding gas. The CO J=21-line intensity peaks towards the front of the head, and along the edges of the tail. The 3CO J=21-antenna temperatures in the head are very similar to those of CO, suggesting very high opacities or column densities, or that there is significant CO self-absorption. There is a narrow rim of CO J=43-emission around the front of the head over a limited velocity range, which correlates with the position of a faint optical rim, and a narrow ridge of 2μm H_2_ emission. These data give strong support to the Radiation Driven Implosion (RDI) model of Lefloch and Lazareff (1994 -- hereafter LL94), which was developed to explain the physical structure of cometary globules. Using an RDI simulation, a remarkably good fit to the data has been obtained, allowing the CO, 3CO and C^18^O spatial structures and velocity field to be modelled. This simulation suggests that Globule 1 is ~400,000years old, and has a mass ~50Msun_. Additional observations towards the region close to IRAS 06314+0427 show that it is associated with an intense molecular concentration lying at the northern end of a ~5pc long molecular ridge, with a mass ~330Msun_, and lies close to the centre of a shell-like condensation.
Aspin C. A.
Dahmen G.
Huldtgren M.
Lefloch Bertrand
Malcolm Fridlund C. V.
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