Related papers: On Monolithic Supermassive Stars
In this review, I present the case for how massive stars may form through stellar collisions. This mechanism requires very high stellar densities, up to 4 orders of magnitude higher than are observed in the cores of dense young clusters. In…
The James Webb Space Telescope (JWST) has recently uncovered a new record-breaking quasar, UHZ1, at a redshift of $z\sim10$. This discovery continues JWST's trend of confronting the expectations from the standard $\Lambda$CDM model of…
The mass distribution of compact objects provides a fossil record that can be studied to uncover information on the late stages of massive star evolution, the supernova explosion mechanism, and the dense matter equation of state.…
Massive stars (with mass m_* > 8 solar masses) are fundamental to the evolution of galaxies, because they produce heavy elements, inject energy into the interstellar medium, and possibly regulate the star formation rate. The individual star…
The stability of metal-free very massive stars ($Z$ = 0; $M = 120 - 500 \msol$) is analyzed and compared with metal-enriched stars. Such zero-metal stars are unstable to nuclear-powered radial pulsations on the main sequence, but the growth…
Here are reviewed the insights from observations at optical and infrared wavelengths for low mass limits above which stars do not seem to end as luminous supernovae. These insights are: (1) the absence in archived images of nearby galaxies…
We have proposed that the first phase of stellar evolution in the history of the Universe may be Dark Stars (DS), powered by dark matter heating rather than by nuclear fusion. Weakly Interacting Massive Particles, which may be their own…
Growing theoretical evidence suggests that the first generation of stars may have been quite massive (~100-300 solar masses). If they retain their high mass until death, such stars will, after about 3Myr, make pair-instability supernovae.…
Using the first 50% of data collected for the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) observations on the 1.8 deg$^2$ Cosmological Evolution Survey (COSMOS) we estimate the masses and star formation rates of 3398…
The evolution and explosion of metal-free stars with masses 10--100 solar masses are followed, and their nucleosynthetic yields, light curves, and remnant masses determined. When the supernova yields are integrated over a Salpeter initial…
Stars mostly form in groups consisting of a few dozen to several ten thousand members. For 30 years, theoretical models provide a basic concept of how such star clusters form and develop: they originate from the gas and dust of collapsing…
The study of the stars that explode as supernovae used to be a forensic study, working backwards from the remnants of the star. This changed in 1987 when the first progenitor star was identified in pre-explosion images. Currently there are…
There is compelling evidence that supermassive black holes (SMBHs) exist. Yet the origin of these objects, or their seeds, is still unknown. We are performing general relativistic simulations of gravitational collapse to black holes in…
We examine the possibility that very massive stars greatly exceeding the commonly adopted stellar mass limit of 150 Msun may be present in young star clusters in the local universe. We identify ten candidate clusters, some of which may host…
The last decade has witnessed significant advances in our observational understanding of the earliest stages of low-mass star formation. The advent of sensitive receivers on large radio telescopes such as the JCMT and IRAM 30m MRT has led…
Observations of the most luminous quasars at redshift z>6 reveal the existence of numerous supermasssive black holes (>10^9 Msun) already in place about twelve billion years ago. In addition, the interstellar medium of the galaxies hosting…
The discovery of massive galaxies at high redshifts, especially the passive ones, poses a big challenge for the current standard galaxy formation models. Here we use the semi-analytic galaxy formation model developed by Henriques et al. to…
The star-forming main sequence of galaxies has now been observed out to redshifts of $z\sim6$ and beyond. However, it remains unclear how long typical galaxies remain on or near it as they evolve, and how frequently they return after…
Accurate mass-loss rates are essential for meaningful stellar evolutionary models. For massive single stars with initial masses between 8 - 30\msun the implementation of cool supergiant mass loss in stellar models strongly affects the…
We review the final stages of stellar evolution, supernova properties, and chemical yields as a function of the progenitor's mass M. (1) 8 - 10 Ms stars are super-AGB stars when the O+Ne+Mg core collapses due to electron capture. These…