NGC 6749: a metal-poor halo globular cluster in a disc field rich in Mira variables

被引:16
作者
Rosino, L
Ortolani, S
Barbuy, B
Bica, E
机构
[1] UNIV PADUA,DEPT ASTRON,I-35122 PADUA,ITALY
[2] UNIV SAO PAULO,IAG,DEPT ASTRON,BR-01065970 SAO PAULO,BRAZIL
[3] UNIV FED RIO GRANDE SUL,DEPT ASTRON,BR-91500970 PORTO ALEGRE,RS,BRAZIL
关键词
stars; variables; other; globular clusters; individual; NGC; 6749; galaxy; halo;
D O I
10.1093/mnras/289.3.745
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present V,I photometry of the loose star cluster NGC 6749, and for the first time colour-magnitude diagrams are provided. We confirm that it is a globular cluster and its blue horizontal branch indicates that it is metal-poor. We derive a reddening of E(B-V) = 1.39 +/- 0.04 and a distance from the Sun d(circle dot), = 7.3 +/- 0.9 kpc (assuming a total-to-selective absorption R = 3.4). The cluster is projected very close to the Galactic plane, and the derived distance implies a Galactic coordinate Z approximate to -300 pc. It is thus a halo globular cluster located close to the disc plane. We also discuss the properties of 78 newly discovered long-period variable stars, of which 75 are Miras, projected within 1 degrees of the cluster centre. The variables do not appear to be associated with the globular cluster. From their periods, most of them belong to the metal-rich disc or bulge stellar populations.
引用
收藏
页码:745 / 752
页数:8
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