star formation tagged posts

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...

Massive galaxy cluster MACS J0416 seen in X-rays (blue), visible light (red, green, and blue), and radio light (pink). Credit: NASA/CXC/SAO/G.Ogrean/STScI/NRAO/AUI/NSF.

Researchers have discovered 4 of the most distant clusters of galaxies ever found, as they appeared when the universe was only 4 billion years old. This sample is now providing the best measurement yet of when and how fast galaxy clusters stop forming stars in the early universe. Clusters are rare regions of the universe consisting of hundreds of galaxies containing trillions of stars, as well as hot gas and mysterious dark matter. Spectroscopic observations from the ground using W. M. Keck Observatory in Hawaii and the Very Large Telescope in Chile confirmed the four candidates to be massive clusters...

Galaxy NGC 2337 in constellation Lynx Credit: ESA/Hubble & NASA

This galaxy, NGC 2337, resides 25 million light-years away in the constellation of Lynx. NGC 2337 is an irregular galaxy, ie —along with a quarter of all galaxies in the universe—lacks a distinct, regular appearance. The galaxy was discovered in 1877 by the French astronomer Édouard Stephan who, in the same year, discovered the galactic group Stephan’s Quintet (heic0910i).

Although irregular galaxies may never win a beauty prize when competing with their more symmetrical spiral and elliptical peers, astronomers consider them to be very important. Some irregular galaxies may have once fallen into one of the regular classes of the Hubble sequence, but were warped and deformed by a passing cosmic companion...