How stars shape galaxies
doi:10.1038/nindia.2009.275 Published online 25 August 2009
Researchers have discovered how formation of a specific type of stars shapes the architecture of Large Magellanic Cloud (LMC), a galaxy lying close to Milky Way, our own galaxy1.
LMC lies 160,000 light years away from Milky Way. It is the third closest galaxy to Milky Way and has a mass equivalent to approximately 10 billion times the mass of our sun. Researchers were interested in studying RR Lyrae stars (RRLS), which are used as a tracer for galaxy halo. Galaxy halo is made of hot gas and dark matter.
Relying on a special type of cosmological survey known as OGLE III survey, the researchers have found two distinct populations (one with smaller scale-height, very similar to the red clump stars and the other, much larger) of RRLS stars formed in the disk of LMC. RRLS identified by the OGLE III survey are used to estimate their number density distribution. These stars are variable stars. The results indicate that the RRLS in the inner LMC trace the disk and probably the inner halo.
The study yields clues to a major star formation event that happened in the LMC about 10-12 billion years ago, resulting in the formation of most of the inner RRLS, as well as probably the globular clusters, inner halo and the disk of the LMC.
- Subramaniam, A. et al. RR Lyrae stars in the inner LMC: Where did they form? Astron. Astrophys. 503, L9-L12 (2009) | Article