by Elizabeth Lovegrove | Feb 13, 2012 | Daily Paper Summaries
When the light from a distant quasar finally arrives at Earth, it often carries far more information than it did when it was emitted – the shadows of gas and galaxies that have intervened over the cosmic distances between us and the source. These features can tell us how the universe evolves in both space and time, by allowing us to sample both low and high redshifts for structures that would not otherwise be visible. This paper uses a new IR spectrograph, FIRE, deployed on the Magellan 6.5 m telescopes, to present the first high-redshift sample of Mg II absorption systems, including the most distant Mg II system yet found (z = 5.33). The authors show that the number of strong Mg II systems appears to peak and decline in number along with the star formation history of the universe, suggesting a correlation between the two, while weak Mg II systems stay mysteriously constant.
by Adele Plunkett | Feb 3, 2012 | Daily Paper Summaries
Title: Line profiles of cores within clusters: I. The anatomy of a filament Authors: Rowan J. Smith, Rahul Shetty, Amelia M. Stutz, Ralf S. Klessen First Author’s Institution: Centre for Astronomy at the University of Heidelberg, GermanyStars are a fundamental component of the universe, building blocks of larger structures like galaxies and galaxy clusters. The cycle of star formation, evolution, death and rebirth, recycling on cosmic scales, is interesting but difficult to observe at all stages. Within our lifetimes, we can’t observe one star as it progresses through a complete life-cycle, but we can observe a variety of stars at a variety of evolutionary stages in order to tell the whole story. However, it remains a challenge to observe stars in the earliest stages as they are forming. Stars form in dense environments obscured by cold dusty material. One tool for identifying star-forming cores (this is the terminology used when a cloud of molecular gas has collapsed and begins to form a star) is the observed blue infall asymmetry. Let me explain.When you (the observer) stare straight into a (spherical) core as it collapses, you will see some gas on the near side of the cloud moving away from you and some gas on the far side of the cloud moving towards you. Remember, you only see a 2-D picture, and using the doppler shifting of light, you will only measure the velocity component projected along the line of sight. Along any line of sight, there will be two elements of gas with similar line-of-sight velocity components. However, considering that the gas is dense enough and becomes opaque at...
by Anna Rosen | Jan 30, 2012 | Daily Paper Summaries
In this article the authors simulate the collapse of a magnetized, turbulent molecular cloud core to see if rotationally supported discs can form around central protostars.
by Evan Schneider | Jan 25, 2012 | Daily Paper Summaries
Young massive stars have a variety of different rotation rates, but what sets these initial speeds? In this paper, the authors investigate whether magnetic fields could be the answer.
by Chris Faesi | Jan 20, 2012 | Daily Paper Summaries
An extremely metal-poor star, which was first discussed on astrobites by Anna in September 2011, may be evidence that dust-induced fragmentation was the catalyst for the change from the top-heavy Initial Mass Function (IMF) of the first stars to the steep IMF we observe 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.
