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Title: A DOUBLE MAIN SEQUENCE IN THE GLOBULAR CLUSTER NGC 6397

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 {approx}30% and {approx}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 {approx}30% of the stars, and (2) a second generation with enhanced sodium and nitrogen, depleted carbon and oxygen, and a slightly enhanced helium abundance ({Delta}Y {approx} 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{sub F336W}. Theoretical isochrones indicate that this could be due to NH depletion.

Authors:
;  [1];  [2];  [3]; ;  [4];  [5];  [6]
  1. Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife, Canary Islands (Spain)
  2. Max Planck Institute for Astrophysics, Postfach 1317, D-85741 Garching (Germany)
  3. Dipartimento di Astronomia, Universita di Padova, Vicolo dell'Osservatorio 3, Padova I-35122 (Italy)
  4. Space Telescope Science Institute, 3800 San Martin Drive, Baltimore, MD 21218 (United States)
  5. INAF-Osservatorio Astronomico di Collurania, via Mentore Maggini, I-64100 Teramo (Italy)
  6. Division of Astronomy and Astrophysics, University of California, Los Angeles, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547 (United States)
Publication Date:
OSTI Identifier:
22011990
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 745; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CARBON; COLOR; HELIUM; NITROGEN; OXYGEN; PHOTOMETRY; SODIUM; STARS; TELESCOPES

Citation Formats

Milone, A. P., Aparicio, A., Marino, A. F., Piotto, G., Bedin, L. R., Anderson, J., Cassisi, S., and Rich, R. M., E-mail: milone@iac.es, E-mail: aparicio@iac.es, E-mail: amarino@MPA-Garching.MPG.DE, E-mail: giampaolo.piotto@unipd.it, E-mail: jayander@stsci.edu, E-mail: bedin@stsci.edu, E-mail: cassisi@oa-teramo.inaf.it, E-mail: rmr@astro.ucla.edu. A DOUBLE MAIN SEQUENCE IN THE GLOBULAR CLUSTER NGC 6397. United States: N. p., 2012. Web. doi:10.1088/0004-637X/745/1/27.
Milone, A. P., Aparicio, A., Marino, A. F., Piotto, G., Bedin, L. R., Anderson, J., Cassisi, S., & Rich, R. M., E-mail: milone@iac.es, E-mail: aparicio@iac.es, E-mail: amarino@MPA-Garching.MPG.DE, E-mail: giampaolo.piotto@unipd.it, E-mail: jayander@stsci.edu, E-mail: bedin@stsci.edu, E-mail: cassisi@oa-teramo.inaf.it, E-mail: rmr@astro.ucla.edu. A DOUBLE MAIN SEQUENCE IN THE GLOBULAR CLUSTER NGC 6397. United States. doi:10.1088/0004-637X/745/1/27.
Milone, A. P., Aparicio, A., Marino, A. F., Piotto, G., Bedin, L. R., Anderson, J., Cassisi, S., and Rich, R. M., E-mail: milone@iac.es, E-mail: aparicio@iac.es, E-mail: amarino@MPA-Garching.MPG.DE, E-mail: giampaolo.piotto@unipd.it, E-mail: jayander@stsci.edu, E-mail: bedin@stsci.edu, E-mail: cassisi@oa-teramo.inaf.it, E-mail: rmr@astro.ucla.edu. 2012. "A DOUBLE MAIN SEQUENCE IN THE GLOBULAR CLUSTER NGC 6397". United States. doi:10.1088/0004-637X/745/1/27.
@article{osti_22011990,
title = {A DOUBLE MAIN SEQUENCE IN THE GLOBULAR CLUSTER NGC 6397},
author = {Milone, A. P. and Aparicio, A. and Marino, A. F. and Piotto, G. and Bedin, L. R. and Anderson, J. and Cassisi, S. and Rich, R. M., E-mail: milone@iac.es, E-mail: aparicio@iac.es, E-mail: amarino@MPA-Garching.MPG.DE, E-mail: giampaolo.piotto@unipd.it, E-mail: jayander@stsci.edu, E-mail: bedin@stsci.edu, E-mail: cassisi@oa-teramo.inaf.it, E-mail: rmr@astro.ucla.edu},
abstractNote = {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 {approx}30% and {approx}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 {approx}30% of the stars, and (2) a second generation with enhanced sodium and nitrogen, depleted carbon and oxygen, and a slightly enhanced helium abundance ({Delta}Y {approx} 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{sub F336W}. Theoretical isochrones indicate that this could be due to NH depletion.},
doi = {10.1088/0004-637X/745/1/27},
journal = {Astrophysical Journal},
number = 1,
volume = 745,
place = {United States},
year = 2012,
month = 1
}
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