Science And Society at IPFW
Indiana University Purdue University Fort wayne
Source of Publication
Place of Publication
The distant Milky Way globular cluster NGC2419 holds the fossil record of dark matter in the early universe. NGC2419 is 13 GYr old. It is thought that globular clusters are the remnants of giant spheroidal stars systems that formed under the gravitational influence of dark matter 13 GYr ago. Winds from supernovae and/or rotating asymptotic giant branch stars removed, in less than 1 Gyr, most of their stars and much of the gas from which new stellar generations form. These winds enriched the primordial gas in carbon+nitrogen+oxygen and helium. The amount of gas that remained de-termined how many more generations of stars would form. The degree of enrichment determined the chemical makeup of the globular cluster stars. It is thought that progenitors containing warm dark matter result in globular clus-ters in who’s second generation of stars formed relatively late. The majority of progenitors with moderate initial mass will hold enough residual gas a second generation of stars to form. However, many globular clusters harbor multiple populations containing a widely differing fractions of carbon+nitrogen+oxygen and helium.These are likely to be the result of mergers between multiple progenitors. Thus, two-population clusters with moderate car-bon+nitrogen+oxygen and helium differences are a signature of warm dark matter in the early universe.
NGC 2419 is one of a handful of clusters with two giant star star populations that differ moderately in chemical makeup.3 It is an ideal system in which to look for the signature of warm dark matter. This work seeks to use the chemi-cal differences between the generations to determine the amount type of dark matter in the early universe.
The helium enrichment causes the second generation to be bluer (for the same luminosity) than the first generation. This blue/red dichotomy is expected to be present in both the red giants and the horizontal branch stars of NGC2419. This paper will show that dissecting the red giant branch reveals two populations of giants, one of which is more cen-trally located than the other. This behavior was seen in eight colors from the ultraviolet to the infrared. This paper will investigate the two stellar populations by comparisons of stellar evolution models and color-magnitude diagrams constructed from photometry in the Hubble Legacy Archive.
Dark Matter, Globular Cluster, Milky Way, Multiple Populations
Astrophysics and Astronomy | Physics
Stephen D. Gillam Dr, Sydnee Hamrick, and Christian Keating (2014).
Two Stellar Populations in The Distant Milky Way Globular Cluster NGC2419. N/A.N/A (N/A), N/A. N/A: N/A.Presented at Science And Society at IPFW, Indiana University Purdue University Fort wayne.