The color-magnitude diagram of the globular cluster NGC 6362 and the canonical tilt of horizontal branches

被引:26
作者
Brocato, E
Castellani, V
Raimondo, G
Walker, AR
机构
[1] Osserv Astron Collurania, I-64100 Teramo, Italy
[2] Univ Pisa, Dipartimento Fis, I-56100 Pisa, Italy
[3] Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, La Serena, Chile
[4] Ist Nazl Fis Nucl, LNGS, I-67100 Laquila, Italy
[5] Ist Nazl Fis Nucl, Sez Pisa, I-56100 Pisa, Italy
关键词
globular clusters : individual (NGC 6362); Hertzsprung-Russell diagram; stars : evolution; stars : horizontal-branch; stars : interiors;
D O I
10.1086/308058
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
In this paper we present new and accurate photometry for stars in the Galactic globular cluster NGC 6362. The color-magnitude diagram discloses two peculiarities in the distribution of stars: (1) a slightly tilted horizontal branch (HB) (Delta(V)(tilt) = 0.1 mag) and (2) a clump of stars near the red edge of the HB. We perform a detailed comparison with theoretical stellar models in both the HB and red giant branch (RGB) phases. It appears that in the moderately metal rich NGC 6362 the tilted HB can be explained as a natural product of canonical evolutionary theories, being a consequence of the minimum in the bolometric correction near 7500 K. We also investigate the effect of decreasing the efficiency of convective transport in stars climbing the RGB. Adopting Z = 0.002 and Y = 0.23, and performing a global fitting with the theoretical isochrones and zero-age HB, an age of 12 +/- 1 Gyr is found, together with (m - M)(V) = 14.68 and E(B - V) = 0.08.
引用
收藏
页码:230 / 235
页数:6
相关论文
共 32 条
[11]   Galactic globular cluster stars: From theory to observation [J].
Cassisi, S ;
Castellani, V ;
Degl'Innocenti, S ;
Salaris, M ;
Weiss, A .
ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES, 1999, 134 (01) :103-113
[12]   THE EVOLUTION OF HE-BURNING STARS - HORIZONTAL AND ASYMPTOTIC BRANCHES IN GALACTIC GLOBULARS [J].
CASTELLANI, V ;
CHIEFFI, A ;
PULONE, L .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1991, 76 (03) :911-977
[13]  
Castelli F, 1997, ASTRON ASTROPHYS, V318, P841
[14]   Bimodality and gaps on globular cluster horizontal branches. II. The cases of NGC 6229, NGC 1851, and NGC 2808 [J].
Catelan, M ;
Borissova, J ;
Sweigart, AV ;
Spassova, N .
ASTROPHYSICAL JOURNAL, 1998, 494 (01) :265-284
[15]   A pulsational approach to the luminosity of horizontal branch stellar structures [J].
De Santis, R ;
Cassisi, S .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1999, 308 (01) :97-110
[16]  
FOURCADE CR, 1974, PASP, V91, P589
[17]   GLOBULAR-CLUSTERS IN GALAXIES [J].
HARRIS, WE ;
RACINE, R .
ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS, 1979, 17 :241-274
[18]   UBVRI PHOTOMETRIC STANDARD STARS IN THE MAGNITUDE RANGE 11.5-LESS-THAN-V-LESS-THAN-16.0 AROUND THE CELESTIAL EQUATOR [J].
LANDOLT, AU .
ASTRONOMICAL JOURNAL, 1992, 104 (01) :340-&
[19]   The variable stars and blue horizontal branch of the metal-rich globular cluster NGC 6441 [J].
Layden, AC ;
Ritter, LA ;
Welch, DL ;
Webb, TMA .
ASTRONOMICAL JOURNAL, 1999, 117 (03) :1313-1331
[20]   A standard stellar library for evolutionary synthesis .1. Calibration of theoretical spectra [J].
Lejeune, T ;
Cuisinier, F ;
Buser, R .
ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES, 1997, 125 (02) :229-246