Recently, Deason et al. suggested that the number ratio between blue stragglers (BSs) and blue horizontal branch stars (BHBs) can be used as a population indicator of various stellar systems. Using this number ratio, they suggested that the Milky Way outer halo formed mostly from dwarf spheroidals rather than globular clusters (GCs). However, we demonstrate that this result is biased because they neglect the effect of BHB stars from helium-enhanced second-generation population on the number ratio. We also perform dynamical evolution models and found that the high BS-to-BHB ratio observed in the outer halo fields is most likely due to the preferential removal of the first-generation stars in GCs. Therefore, the BS-to-BHB number ratio is not a good population indicator for claiming that more massive dwarf galaxies are the main building blocks of the Milky Way outer halo.
|Number of pages||2|
|Journal||Memorie della Societa Astronomica Italiana - Journal of the Italian Astronomical Society|
|Publication status||Published - 2016|
|Event||2016 Cosmic-Lab Conference: Star Clusters as Cosmic Laboratories for Astrophysics, Dynamics and Fundamental Physics, MODEST 2016 - Bologna, Italy|
Duration: 2016 Apr 18 → 2016 Apr 22
Bibliographical notePublisher Copyright:
© 2016 SAIt.
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering
- Radiology Nuclear Medicine and imaging
- Astronomy and Astrophysics
- Atomic and Molecular Physics, and Optics