An irritating aspect of this astrobite is that it doesn't explain the difference between faint dwarf galaxies and stars clusters. Would the main difference be that the members of a star cluster would all be more or less the same age, whereas there should be more than one generation of a stars in a galaxy?bystander wrote: ↑Wed Feb 13, 2019 6:05 pmLooking Deeper at Milky Way Satellite Dwarf Galaxy Candidates
astrobites | Daily Paper Summaries | 2019 Feb 13Amy Miller wrote:
Dwarf galaxies are believed to be the fundamental building blocks of larger galaxies like our Milky Way and are the most abundant galaxies in our known universe. Astronomers use the terms “satellite” or “companion” galaxy to denote less massive galaxies that orbit around a larger galaxy’s center of mass. Two of the most well-known dwarf galaxies are the Large and Small Magellanic Clouds—satellite galaxies of the Milky Way. Though vitally important to galaxy formation and evolution, astronomers have a difficult time producing adequate numbers of them in cosmological simulations. Computer simulations that test the Lambda Cold Dark Matter (ΛCDM) model—the standard model of Big Bang Cosmology—predict that there should be at least 100, and possibly up to a 1000, satellite galaxies orbiting the Milky Way. However, there are only about 50 known Milky Way companions. This huge discrepancy between theory and observation has been dubbed the “missing satellites problem.” Solutions to this problem are a hot topic of debate in the astronomy community.
Meanwhile, increasingly sensitive data are revealing more Milky Way dwarf satellite candidates. Recent work done in two separate papers led by K. Bechtol and A. Drlica-Wagner revealed 16 new Milky Way dwarf satellite candidates in ~5000 square degrees of the southern sky. These candidates were found by analyzing astronomical data catalogs from the Dark Energy Survey and identifying overdensities of stellar populations. Although these 16 overdensities were previously unidentified, it is still unclear as to whether they are dwarf satellite galaxies or star clusters. By gathering more light to see even fainter stars, the subject of today’s Astrobite uses “deeper” images than the Dark Energy Survey to further investigate the exact nature of four of these stellar populations. These deeper data give more information to the authors and allow them to make better estimations as to whether they are dwarf galaxies or star clusters.
On the Nature of Ultra-faint Dwarf Galaxy Candidates.
III. Horologium I, Pictor I, Grus I, and Phoenix II ~ Helmut Jerjen et al
- arXiv.org > astro-ph > arXiv:1809.02259 > 07 Sep 2018