Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-11-10
Astronomy and Astrophysics
Astrophysics
9 pages, 10 Figures. Accepted for publication in MNRAS
Scientific paper
10.1111/j.1365-2966.2007.12592.x
We present an analysis of HI, H-alpha, and oxygen abundance data for NGC 3741. This galaxy has a very extended gas disk (~8.8 times the Holmberg radius), and a dark to luminous (i.e. stellar) mass ratio of ~149, which makes it one of the ``darkest'' dwarf irregular galaxies known. However its ratio of baryons (i.e. gas + stellar) mass to dark mass is typical of that in galaxies. Our new high-resolution HI images of the galaxy show evidence for a large scale (purely gaseous) spiral arm and central bar. Despite the gaseous spiral feature and the on-going star formation, we find that the global gas density in NGC 3741 is significantly lower than the Toomre instability criterion. We also find that the star formation rate is consistent with that expected from the observed correlations between HI mass and SFR and the global Kennicutt-Schmidt law respectively. We measure the oxygen abundance to be 12+ log(O/H)=7.66$\pm$0.10, which is consistent with that expected from the metallicity-luminosity relation, despite its extreme gas mass ratio. We also examine the issue of chemical evolution of NGC 3741 in the context of closed-box model of chemical evolution. The effective oxygen yield of NGC 3741 is consistent with recent model estimates of closed-box yields, provided one assumes that the gas has been efficiently mixed all the way to edge of the HI disk (i.e. >8 times the optical radius). This seems a priori unlikely. On the other hand, using a sample of galaxies with both interferometric HI maps and chemical abundance measurements, we find that the effective yield is anti-correlated with the total dynamical mass, as expected in leaky box models (slightly abridged).
Begum Ayesha
Chengalur Jayaram N.
Karachentsev Igor D.
Kennicutt Robert C.
Lee Janice C.
No associations
LandOfFree
Life in the last lane: Star formation and chemical evolution in an extremely gas-rich dwarf 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 Life in the last lane: Star formation and chemical evolution in an extremely gas-rich dwarf, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Life in the last lane: Star formation and chemical evolution in an extremely gas-rich dwarf will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-27650