NASA | JPL-Caltech | Spitzer | 2014 Dec 05
Some like it hot, but for creating new stars, a cool cosmic environment is ideal. As a new study suggests, a surge of warm gas into a nearby galaxy -- left over from the devouring of a separate galaxy -- has extinguished star formation by agitating the available chilled gas.
The unique findings illustrate a new dimension to galaxy evolution, and come courtesy of the European Space Agency's Herschel space observatory, in which NASA played a key role, and NASA's Spitzer and Hubble space telescopes.
Astronomers want to understand why galaxies in the local universe fall into two major categories: younger, star-forming spirals (like our own Milky Way), and older ellipticals, in which fresh star making has ceased. The new study's galaxy, NGC 3226, occupies a transitional middle ground, so getting a bead on its star formation is critical. ...
NGC 3226 is relatively close, just 50 million light-years away. Several star-studded, gassy loops emanate from NGC 3226. Filaments also run out from it and between a companion galaxy, NGC 3227. These streamers of material suggest that a third galaxy probably existed there until recently -- that is, until NGC 3226 cannibalized it, strewing pieces of the shredded galaxy all over the area.
A prominent piece of these messy leftovers stretches 100,000 light-years and extends right into the core of NGC 3226. This long tail ends as a curved plume in a disk of warm hydrogen gas and a ring of dust. Contents of the tail, thought to be the debris from that departed galaxy, are falling into NGC 3226, drawn by its gravity. ...
Accretion-Inhibited Star Formation in the Warm Molecular Disk of the Green-valley Elliptical Galaxy NGC 3226 - P. N. Appleton et al
- Astrophysical Journal 797(2) 117 (2014 Dec 20) DOI: 10.1088/0004-637X/797/2/117
arXiv.org > astro-ph > arXiv:1410.7347 > 27 Oct 2014 (v1), 30 Oct 2014 (v2)