NASA | STScI | HubbleSite | 2016 Aug 11
[img3="Dwarf Galaxies in Pisces - Credit: NASA, ESA, and E. Tollerud (STScI)"]http://imgsrc.hubblesite.org/hu/db/imag ... _print.jpg[/img3][hr][/hr]NASA's Hubble Space Telescope has uncovered two tiny dwarf galaxies that have wandered from a vast cosmic wilderness into a nearby "big city" packed with galaxies. After being quiescent for billions of years, they are ready for partying by starting a firestorm of star birth.
"These Hubble images may be snapshots of what present-day dwarf galaxies may have been like at earlier epochs," said lead researcher Erik Tollerud of the Space Telescope Science Institute in Baltimore, Maryland. "Studying these and other similar galaxies can provide further clues to dwarf galaxy formation and evolution."
The Hubble observations suggest that the galaxies, called Pisces A and B, are late bloomers because they have spent most of their existence in the Local Void, a region of the universe sparsely populated with galaxies. The Local Void is roughly 150 million light-years across.
Under the steady pull of gravity from the galactic big city, the loner dwarf galaxies have at last entered a crowded region that is denser in intergalactic gas. In this gas-rich environment, star birth may have been triggered by gas raining down on the galaxies as they plow through the denser region. Another idea is that the duo may have encountered a gaseous filament, which compresses gas in the galaxies and stokes star birth. Based on the galaxies' locations, Tollerud's team determined that the objects are at the edge of a nearby filament of dense gas. Each galaxy contains about 10 million stars. ...
HST Imaging of the Local Volume Dwarf Galaxies Pisces A&B: Prototypes for Local Group Dwarfs - Erik J. Tollerud et al
- Astrophysical Journal 827(2):89 (20 Aug 2016) DOI: 10.3847/0004-637X/827/2/89
arXiv.org > astro-ph > arXiv:1607.03487 > 12 Jul 2016