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And now there’s a problem with M dwarfs, too
The basis for something called the “G dwarf problem” is the comparison between observations and a simple model for chemical evolution in a galaxy. To cut to the chase, there are fewer very metal poor G dwarfs than are predicted by this basic understanding. This discrepancy has been shown to hold for the Milky Way as well as for other galaxies. It also holds for K dwarfs in the Milky Way – and now for M dwarfs as well.
Understanding star formation is all about perspective
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...
A Planet Being Destroyed?
A very small rocky planet—close to the size of Mercury—is evaporating as it orbits the host star. The putative planet orbits the star in less than 16 hours, so the planet’s surface is highly irradiated. The planet would actually be hot enough to vaporize rocky material at the surface, which could escape the gravitational pull of the planet and form a comet-like tail trailing the orbit.
Constraining the Proton-to-Electron Mass Ratio over Cosmic Time
Using a rotational transition of methanol, this paper attempts to see if a fundamental constant has changed over cosmic time.
A planet diminished
When new evidence disagrees with our previous understanding, we must reinterpret everything.