by Anna Rosen | Mar 27, 2012 | Daily Paper Summaries
Could stars with masses 100,000 times more massive than our Sun exist? Are these the possible progenitors for supermassive black holes that litter our universe today?
by Michelle Kislak | Jan 18, 2012 | Daily Paper Summaries
The first simulations of low-mass star formation on parsec scales to include protostellar feedback successfully reproduce observed mass functions, luminosities, and clustering properties.
by Nathan Goldbaum | Nov 13, 2011 | Daily Paper Summaries
Paper title: Protostellar Feedback Halts the Growth of the First Stars in the Universe Authors: Takashi Hosokawa, Kazuyuki Omukai, Naoki Yoshida, Harold W. Yorke Author’s Affiliation: Jet Propulsion Laboratory; Department of Physics, Kyoto UniversityThe problem of understanding the formation and evolution of the first to form stars in the universe lies at the intersection of many fields of astrophysics. Since the first stars could only have formed once their host dark matter halos had begun to collapse, one must understand the formation of these stars in a cosmological context, tracking gas from extremely low intergalactic densities (~10-27 g cm-3), to extremely high, stellar densities (~1 g cm-3). Since all the metal content of the universe had not yet been synthesized in the cores of stars, the gas that collapsed to form the first stars would have been metal-free and thus possessed very different thermal properties compared to the interstellar and intergalactic gas in the local universe that can cool via metal line emission.Many studies of first star formation have focused on the cosmological piece of the puzzle: starting with a simulation of cold dark matter and gas in a ΛCDM cosmology, they look for the first ~106 solar mass dark matter halo to collapse, and then follow the collapse of first the dark matter and then the gas to very high densities. Due to the extremely large dynamic range in these simulations, it becomes prohobitively expensive to reach stellar densities and impossible to directly model the evolution of the first star. For reference, a recent simulation of the formation of the first stars followed the collapse to densities just above 10-8 g cm-3, far below typical stellar...
by Elisabeth Newton | Sep 28, 2011 | Daily Paper Summaries
Stars form in environments that are characterized by vastly different densities, pressures and metal content. Yet the sizes of the stars formed don’t vary substantially (as measured by the median mass). Why don’t the properties of the clouds out of which stars fragment have a stronger influence on the result? Why is there a characteristic stellar mass? Why is this mass scale similar to that for nuclear burning (the process that fuels stars)?
(photo: NASA via LANL, https://www.llnl.gov/news/newsreleases/2005/NR-05-11-10.html)
by Astrobites | Aug 21, 2011 | Undergraduate Research
A couple of weeks ago we put out a call for descriptions of research being done by undergraduates, and we got a great response! Today we’re publishing the first installment.
by Susanna Kohler | May 20, 2011 | Daily Paper Summaries
What prevents newly-formed stars from spinning so fast that they break apart? This paper explores the effectiveness of gravitational torque as a braking force.