star formation tagged posts

A deep optical image of the gas-rich galaxy GASS 3505 which in at radio wavelengths shows a ring of neutral hydrogen gas, probably a result of accretion (there is a faint streamer seen to the left in this image). Astronomers conclude that the star formation in this object is very weak, less than about 0.1 solar-masses per year. Credit: Gereb et al. 2016

Cold gas in the form of neutral hydrogen atoms provides the reservoir for star formation in galaxies from the distant to the nearby Universe. Understanding how it accretes onto galaxies is of crucial importance because fresh supplies of gas fuel the ongoing star-forming...

Galaxies IC 2163 (left) and NGC 2207 (right) recently grazed past each other, triggering a tsunami of stars and gas in IC 2163 and producing the dazzling eyelid-like features there. ALMA image of carbon monoxide (orange), which revealed motion of the gas in these features, is shown on top of Hubble image (blue) of the galaxy pair. Credit: M. Kaufman; B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble Space Telescope

Astronomers using ALMA have discovered a tsunami of stars and gas that is crashing midway through the disk of a spiral galaxy known as IC 2163. This colossal wave of material – which was triggered when IC 2163 recently sideswiped another spiral galaxy NGC 2207 – produced dazzling arcs of intense star formation that resemble a pair of eyelids...

Stock image. A new study presents the first measurements of the changing strengths of oxygen emission lines from the present day and back to 12.5 billion years ago. Credit: © robert / Fotolia

A new study casts light on how young, hot stars ionize oxygen in the early universe and the effects on the evolution of galaxies through time. It presents the first measurements of the changing strengths of oxygen emission lines from the present day and back to 12.5 billion years ago. The strength of doubly ionized oxygen increases going back in time, while the strength of singly ionized oxygen increases up to 11 billion years ago and then decreases for the remaining 1 to 2 billion years.

The cause of the two different evolutions is due to the changing physical conditions inside star-forming galaxies...

An image of the giant molecular cloud complex, Mon R2. A far-infrared study of the numbers of dense clumps across this cloud has found statistical correlations that depend on the relative dominance of turbulence versus gravity. Credit: Adam Block, Mt. Lemmon SkyCenter, U. Arizona

Stars form within the dense regions of diffuse molecular clouds, but the physical processes that determine the locations, rate, and efficiency of star formation are poorly understood. Recent thinking envisions a 2-step process: first, a network of dense filaments form due to large-scale turbulence and then fragmentation into cores occurs as gravity starts to dominate...