Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-04-04
Astronomy and Astrophysics
Astrophysics
To be published in ApJ; better figures available ftp.lowell.edu, cd pub/dah/n2366paper
Scientific paper
10.1086/321611
We present UBVJHKHalpha and HI data of the irregular galaxy NGC 2366. It is a normal boxy-shaped disk seen at high inclination angle. We do not see any unambiguous observational signature of a bar. There is an asymmetrical extension of stars along one end of the major axis of the galaxy, and this is where the furthest star-forming regions are found, at 1.3R_Holmberg. The HI is normal in many respects but shows some anomalies: 1) The integrated HI shows two ridges running parallel to the major axis that deproject to a large ring. 2) The velocity field exhibits several large-scale anomalies superposed on a rotating disk. 3) The inclination and position angles derived from the kinematics differ from those dervied from the optical and HI mor- phology. 4) There are regions in the HI of unusually high velocity dispersion that correlate with deficits of HI emission in a manner suggestive of long-range, turbulent pressure equilibrium. Star-forming regions are found where the gas densities locally exceed 6 Msolar/pc^2. NGC 2366, like other irregulars, has low gas densities relative to the critical gas densities of gravitational instability models. Because of the lack of shear in the optical galaxy, there is little competition to the slow gravitational contraction that follows energy dissipation. However, the peak gas densities in the star-forming regions are equal to the local tidal densities for gravitational self-binding of a rotating cloud. Evidently the large scale gas concentrations are marginally bound against background galactic tidal forces. This condition for self-binding may be more fundamental than the instability condition because it is local, three-dimensional, and does not involve spiral arm generation as an intermediate step toward star formation.
Elmegreen Bruce G.
Hunter Deidre Ann
van Woerden Hugo
No associations
LandOfFree
Neutral Hydrogen and Star Formation in the Irregular Galaxy NGC 2366 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Neutral Hydrogen and Star Formation in the Irregular Galaxy NGC 2366, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Neutral Hydrogen and Star Formation in the Irregular Galaxy NGC 2366 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-602431