Related papers: The Luminosity Problem: Testing Theories of Star F…
A review is presented of some of the ingredients, assumptions and techniques that are used in the computation of the structure and evolution of low-mass stars. Emphasis is placed on several ingredients which are still subject to…
The Cygnus-X star-forming complex is one of the most active regions of low and high mass star formation within 2 kpc of the Sun. Using mid-infrared photometry from the IRAC and MIPS Spitzer Cygnus-X Legacy Survey, we have identified over…
There is accumulating evidence that the faint end of the galaxy luminosity function might be very different in different locations. The luminosity function might be sharply rising in rich clusters and flat or declining in regions of low…
The stellar initial mass function at high redshift is an important defining property of the first stellar systems to form and may also play a role in various dark matter problems. We here determine the faint stellar luminosity function in…
Theoretical prediction of surface stellar abundances of light elements -- lithium, beryllium, and boron -- represents one of the most interesting open problems in astrophysics. As well known, several measurements of 7-Li abundances in…
Young galaxies are clumpy, gas-rich, and highly turbulent. Star formation appears to occur by gravitational instabilities in galactic disks. The high dispersion makes the clumps massive and the disks thick. The star formation rate should be…
Understanding the physics of how stars form is a highly-prioritized goal of modern Astrophysics, in part because star formation is linked to both galactic dynamics on large scales and to the formation of planets on small scales. It is…
Using studies of nearby star formation with Spitzer, I will argue that star formation is restricted to dense cores within molecular clouds. The nature of these dense cores and their connection to star formation will be discussed. Their…
We investigate the conditions under which the first low-mass stars formed in the universe by confronting theoretical predictions governing the transition from massive Population III to low-mass Population II stars with recent observational…
We investigate the thermal and dynamical evolution of primordial gas clouds in the universe after decoupling. Comparing the time-scale of dynamical evolution with that of fragmentation, we can estimate the typical fragmentation scale. We…
Cold dark clouds are nearby members of the densest and coldest phase in the galactic interstellar medium, and represent the most accessible sites where stars like our Sun are currently being born. In this review we discuss recent progress…
Stars and star clusters form by gravoturbulent fragmentation of interstellar gas clouds. The supersonic turbulence ubiquitously observed in Galactic molecular gas generates strong density fluctuations with gravity taking over in the densest…
Optically thin cooling gas at most temperatures above 30K will make condensations by pressure pushing material into cool dense regions. This works without gravity. Cooling condensations will flatten and become planar/similarity solutions.…
Using a quantitative model for bipolar outflows driven by hydromagnetic protostellar winds, we calculate the efficiency of star formation assuming that available gas is either converted into stars or ejected in outflows. We estimate the…
Low-mass dense cores represent the state of molecular gas associated with the earliest phases of low-mass star formation. Such cores are called "protostellar" or "starless," depending on whether they do or do not contain compact sources of…
Paczy\'nski (1986) suggested that ``dark" objects in the halo of our Galaxy could enhance the luminosity of foreground stars, acting as gravitational microlenses. Such events has been recently reported by different collaborations. We assume…
Understanding the formation of the first stars and galaxies is a key problem in modern cosmology. In these lecture notes, we will derive some of the basic physical principles underlying this emerging field. We will consider the basic…
Studies of evolved massive stars indicate that they form in a clustered mode. During the earliest evolutionary stages, these regions are embedded within their natal cores. Here, we show high-spatial-resolution interferometric dust continuum…
This article synthesizes observational data from an extensive program aimed toward a comprehensive understanding of star formation in a low-mass star-forming molecular cloud. New observations and published data spanning from the centimeter…
The elegance of inflationary cosmology and cosmological perturbation theory ends with the formation of the first stars and galaxies, the initial sources of light that launched the phenomenologically rich process of cosmic reionization. Here…