A starburst galaxy is a galaxy in the process of "giving birth" to stars at a much quicker rate than normal. Starburst conditions are thought to be brief, only a part of the lifetime of a galaxy or cluster. It can be a natural part of the life-cycle or triggered by galactic collisions or near collisions, flybys close enough for gravity to be a powerful influence.
New studies on starburst galaxies we released recently. These scientists use the Hubble Space Telescope to inspect these starburst galaxys' stellar halos, outer stellar envelopes comprised of intermediate to old age stars. Their conclusions back up previous similar studys' conclusions:
"[These studied] galaxies have faint outer stellar envelopes, and are not tidally truncated within the range of radii addressed by our study."
With a tiny bit of info, the captions to the following images become clear. The images below were taken by Hubble's powerful instrument, the Advanced Camera for Surveys (ASC). The F# notations refer to filters used in observation. The boxes superimposed show their attention to the outer shells in study. The term NGC is used throughout astronomy, standing for the "New General Catalog of Nebulae and Clusters of Stars," a cataloging system of almost 8000 celestial objects.
The new scientific paper on arXiv is titled:
"Hubble Space Telescope study of resolved red giant stars in the outer halos of nearby dwarf starburst galaxies"
Here's a beautiful picture of one of the galaxies being studied, Fig. 1: NGC 1569
"ACS 3-color F658N (Hα), F814W (I) and F606W (V ) composite image of NGC 1569 showing the locations of ACS subfields. Owing to the decrease in stellar density in the outer portions of the galaxy, we increased the size of our boxes as we move outward from the center of the galaxy."
Image Credit: Fig. 1 (cite at bottom)
Another gem of a find is Fig. 2 in the same paper this time of NGC 4449
"ACS 4-color F435W (B), F555W (V ), F814W (I), and F658N (Hα) composite image of NGC 4449 showing the locations of ACS subfields."
Image Credit: Fig. 2 (cite at bottom)
Disclaimer: Just because these starbursts are purple doesn't make them grape flavored.
Agnieszka Ryś, Aaron J. Grocholski, Roeland P. van der Marel, Alessandra Aloisi, & Francesca Annibali (2011). Hubble Space Telescope study of resolved red giant stars in the outer
halos of nearby dwarf starburst galaxies A&A arXiv: 1104.0899v1
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