Year: 2011
Type: article
Abstract: High-precision multi-band Hubble Space Telescope ( HST ) photometry reveals that the main sequence of the globular cluster NGC 6397 splits into two components, containing ∼30% and ∼70% of the stars. This double sequence is consistent with the idea that the cluster hosts two stellar populations: (1) a primordial population that has a composition similar to field stars, containing ∼30% of the stars, and (2) a second generation with enhanced sodium and nitrogen, depleted carbon and oxygen, and a slightly enhanced helium abundance (Δ Y ∼ 0.01). We examine the color difference between the two sequences across a variety of color baselines and find that the second sequence is anomalously faint in m F336W . Theoretical isochrones indicate that this could be due to NH depletion.
Source: The Astrophysical Journal
Authors: A. P. Milone, A. F. Marino, G. Piotto, L. R. Bedin, J. Anderson, A. Aparicio, S. Cassisi, R. M. Rich
Institutions: Universidad de La Laguna, Instituto de Astrofísica de Canarias, Max Planck Institute for Astrophysics, University of Padua, Osservatorio Astronomico di Padova, National Institute for Astrophysics, Space Telescope Science Institute, Collurania Teramo Observatory, University of California, Los Angeles
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2018893297