A DOUBLE MAIN SEQUENCE IN THE GLOBULAR CLUSTER NGC 6397

被引：93

作者：

Milone, A. P. ^{[1
,2
]}

Marino, A. F. ^{[3
]}

Piotto, G. ^{[4
,5
]}

Bedin, L. R. ^{[6
]}

Anderson, J. ^{[6
]}

Aparicio, A. ^{[1
,2
]}

Cassisi, S. ^{[7
]}

Rich, R. M. ^{[8
]}

机构：

[1] Inst Astrofis Canarias, E-38200 San Cristobal la Laguna, Tenerife, Spain

[2] Univ La Laguna, Dept Astrophys, E-38200 San Cristobal la Laguna, Tenerife, Spain

[3] Max Planck Inst Astrophys, D-85741 Garching, Germany

[4] Univ Padua, Dipartimento Astron, I-35122 Padua, Italy

[5] INAF Osservatorio Astron Padova, I-35122 Padua, Italy

[6] Space Telescope Sci Inst, Baltimore, MD 21218 USA

[7] INAF Osservatorio Astron Collurania, I-64100 Teramo, Italy

[8] Univ Calif Los Angeles, Div Astron & Astrophys, Los Angeles, CA 90095 USA

来源：

ASTROPHYSICAL JOURNAL | 2012年 / 745卷 / 01期

关键词：

globular clusters: individual (NGC 6397); stars: Population II; MULTIPLE STELLAR POPULATIONS; ADVANCED CAMERA; OMEGA-CENTAURI; GIANT STARS; ACS SURVEY; ABUNDANCES; NGC-6397; BRANCH; ASTROMETRY; NGC-2808;

D O I：

10.1088/0004-637X/745/1/27

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

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 similar to 30% and similar to 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 similar to 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 similar to 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.

引用

页数：10

共 49 条

[1]

Anderson A. J., 1997, PhD thesis

[2] Ground-based CCD astrometry with wide field imagers - I. Observations just a few years apart allow decontamination of field objects from members in two globular clusters [J].

Anderson, J. ;

Bedin, L. R. ;

Piotto, G. ;

Yadav, R. S. ;

Bellini, A. .

ASTRONOMY & ASTROPHYSICS, 2006, 454 (03) :1029-1045

[3] MIXED POPULATIONS IN GLOBULAR CLUSTERS: ET TU, 47 TUC? [J].

Anderson, J. ;

Piotto, G. ;

King, I. R. ;

Bedin, L. R. ;

Guhathakurta, P. .

ASTROPHYSICAL JOURNAL LETTERS, 2009, 697 (01) :L58-L62

[4]

Anderson J., 2006, PSFs, Photometry, and Astronomy for the ACS/WFC, Instrument Science Report ACS 2006-01

[5] Deep advanced camera for surveys imaging in the globular cluster NGC6397: Reduction methods [J].

Anderson, Jay ;

King, Ivan R. ;

Richer, Harvey B. ;

Fahlman, Gregory G. ;

Hansen, Brad M. S. ;

Hurley, Jarrod ;

Kalirai, Jasonjot S. ;

Rich, R. Michael ;

Stetson, Peter B. .

ASTRONOMICAL JOURNAL, 2008, 135 (06) :2114-2128

[6] The ACS Survey of Globular Clusters. v. generating a comprehensive star catalog for each cluster [J].

Anderson, Jay ;

Sarajedini, Ata ;

Bedin, Luigi R. ;

King, Ivan R. ;

Piotto, Giampaolo ;

Reid, I. Neill ;

Siegel, Michael ;

Majewski, Steven R. ;

Paust, Nathaniel E. Q. ;

Aparicio, Antonio ;

Milone, Antonino P. ;

Chaboyer, Brian ;

Rosenberg, Alfred .

ASTRONOMICAL JOURNAL, 2008, 135 (06) :2055-2073

[7] Transforming observational data and theoretical isochrones into the ACS/WFC Vega-mag system [J].

Bedin, LR ;

Cassisi, S ;

Castelli, F ;

Piotto, G ;

Anderson, J ;

Salaris, M ;

Momany, Y ;

Pietrinferni, A .

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2005, 357 (03) :1038-1048

[8] ω Centauri:: The population puzzle goes deeper [J].

Bedin, LR ;

Piotto, G ;

Anderson, J ;

Cassisi, S ;

King, IR ;

Momany, Y ;

Carraro, G .

ASTROPHYSICAL JOURNAL, 2004, 605 (02) :L125-L128

[9] CARBON ABUNDANCES IN RED GIANT STARS IN THE GLOBULAR-CLUSTERS M92 AND NGC-6397 [J].

BELL, RA ;

DICKENS, RJ ;

GUSTAFSSON, B .

ASTROPHYSICAL JOURNAL, 1979, 229 (02) :604-623

[10] Astrometry and Photometry with HST WFC3. II. Improved Geometric-Distortion Corrections for 10 Filters of the UVIS Channel [J].

Bellini, A. ;

Anderson, J. ;

Bedin, L. R. .

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 2011, 123 (903) :622-637

← 1 2 3 4 5 →