相关论文: Formation of OB Associations in Galaxies
We investigate the relation between the star-formation activity in galaxies and environment at z=1.2 in the COSMOS field, using the fraction of [OII] emitters and the local galaxy density. The fraction of [OII] emitters appears to be almost…
Observations of the nearby large galaxies that can be examined in particularly close detail suggest that many have small stellar luminosity fractions in bulges and haloes. Simulations of galaxy formation tend to produce considerably larger…
We investigate the effects of radiation pressure from stars on the survival of the star-forming giant clumps in high-redshift massive disc galaxies, during the most active phase of galaxy formation. The clumps, typically of mass ~10^8-10^9…
Observations show that star formation in galaxies is closely correlated with the abundance of molecular hydrogen. Modeling this empirical relation from first principles proves challenging, however, and many questions regarding its…
Star clusters are born in a highly compact configuration, typically with radii of less than about 1 pc roughly independently of mass. Since the star-formation efficiency is less than 50 per cent by observation and because the residual gas…
We show that the gas mass fraction of spiral galaxies is strongly correlated with luminosity and surface brightness. It is not correlated with linear size. Gas fraction varies with luminosity and surface brightness at the same rate,…
Studies by Lada (2010) and Heiderman (2010) have suggested that star formation mostly occurs above a threshold in gas surface density Sigma of Sigma_c = 120 Msun pc^{-2} (A_K = 0.8). Heiderman infer a threshold by combining low-mass…
We assess the relationships between the surface densities of the gas and star formation rate (SFR) within spiral arms of the nearby late-type spiral galaxies M81 and M101. By analyzing these relationships locally, we derive empirically a…
We use observed radial profiles of mass surface densities of total, $\Sigma_g$, & molecular, $\Sigma_{\rm H2}$, gas, rotation velocity & star formation rate (SFR) surface density, $\Sigma_{\rm sfr}$, of the molecular-rich ($\Sigma_{\rm…
Star-formation is one of the main processes that shape galaxies, defining its stellar population and metallicity production and enrichment. It is nowadays known that this process is ruled by a set of relations that connect three parameters:…
We invoke star formation triggered by cloud-cloud collisions to explain global star formation rates of disk galaxies and circumnuclear starbursts. Previous theories based on the growth rate of gravitational perturbations ignore the…
Gas processes affecting star formation are reviewed with an emphasis on gravitational and magnetic instabilities as a source of turbulence. Gravitational instabilities are pervasive in a multi-phase medium, even for sub-threshold column…
The chemical abundances in the atmosphere of a star provide unique information about the gas from which that star formed, and, modulo processes that are not important for the vast majority of stars, such as mass transfer in close binary…
We report on a sample of 51 nearby, star-forming galaxies observed with the Cosmic Origin Spectrograph on the Hubble Space Telescope. We calculate Si II kinematics and densities arising from warm gas entrained in galactic outflows. We use…
Recent observations have revealed massive galactic molecular outflows that may have physical conditions (high gas densities) required to form stars. Indeed, several recent models predict that such massive galactic outflows may ignite star…
The timescale for star formation, a measure of how quickly neutral gas is being converted to stars, is considerably longer than typical dynamical timescales associated with a galactic disk. For purposes of modeling galaxy evolution,…
The fractal structure of star formation on large scales in disk galaxies is studied using the size distribution function of stellar aggregates in kpc-scale star fields. Achival HST images of 10 galaxies are Gaussian smoothed to define the…
We propose an "extended Schmidt law" with explicit dependence of the star formation efficiency (SFE=SFR/Mgas) on the stellar mass surface density. This relation has a power-law index of 0.48+-0.04 and an 1-sigma observed scatter on the SFE…
Most stars form in compact, dense embedded clusters with memberships ranging from a dozen stars to many millions of stars. Embedded clusters containing more than a few hundred stars also contain O stars that disrupt the nebula abruptly.…
In search for a synthetic understanding, a scenario for the evolution of the star formation rate and the chemical abundances in galaxies is proposed, combining gas infall from galactic halos, outflow of gas by supernova explosions, and an…