Red clump morphology as evidence against a new intervening stellar population as the primary source of microlensing toward the Large Magellanic Cloud

被引:42
作者
Beaulieu, JP [1 ]
Sackett, PD [1 ]
机构
[1] Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands
关键词
galaxies : individual; galaxies : kinematics and dynamics; Galaxy : halo; Local Group; dark matter;
D O I
10.1086/300400
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We examine the morphology of the color-magnitude diagram (CMD) for core helium burning (red clump) stars to test the recent suggestion by Zaritsky & Lin that an extension of the red clump in the Large Magellanic Cloud (LMC) toward brighter magnitudes is the result of an intervening population of stars that is responsible for a significant fraction of the observed microlensing toward the LMC. Using our own CCD photometry of several fields across the LMC, we confirm the presence of this additional red clump feature but conclude that it is caused by stellar evolution rather than a foreground population. We do this by demonstrating that the feature (1) is present in all our LMC fields, (2) is in precise agreement with the location of the blue loops in the isochrones of intermediate-age red clump stars with the metallicity and age of the LMC, (3) has a relative density consistent with stellar evolution and LMC star formation history, and (4) is present in the Hipparcos CMD for the solar neighborhood, where an intervening population cannot be invoked. Assuming there is no systematic shift in the model isochrones, which fit the Hipparcos data in detail, a distance modulus of mu(LMC) = 18.3 provides the best fit to our dereddened CMD.
引用
收藏
页码:209 / 219
页数:11
相关论文
共 39 条
  • [1] Is the Large Magellanic Cloud microlensing due to an intervening dwarf galaxy?
    Alcock, C
    Allsman, RA
    Alves, DR
    Axelrod, TS
    Becker, AC
    Bennett, DP
    Cook, KH
    Freeman, KC
    Griest, K
    Lehner, MJ
    Marshall, SL
    Minniti, D
    Peterson, BA
    Pratt, MR
    Quinn, PJ
    Rodgers, AW
    Rorabeck, A
    Stubbs, CW
    Sutherland, W
    Tomaney, AB
    Vandehei, T
    Welch, DL
    [J]. ASTROPHYSICAL JOURNAL, 1997, 490 (01) : L59 - L63
  • [2] The MACHO Project Large Magellanic Cloud microlensing results from the first two years and the nature of the Galactic dark halo
    Alcock, C
    Allsman, RA
    Alves, D
    Axelrod, TS
    Becker, AC
    Bennett, DP
    Cook, KH
    Freeman, KC
    Griest, K
    Guern, J
    Lehner, MJ
    Marshall, SL
    Petersons, BA
    Pratt, MR
    Quinn, PJ
    Rodgers, AW
    Stubbs, CW
    Sutherland, W
    Welch, DL
    [J]. ASTROPHYSICAL JOURNAL, 1997, 486 (02) : 697 - 726
  • [3] BEAULIEU JP, 1995, ASTRON ASTROPHYS, V299, P168
  • [4] BENNETT D, 1997, APJ, V493, pL79
  • [5] BERTELLI G, 1994, ASTRON ASTROPHYS SUP, V106, P275
  • [6] RED GIANTS IN OLD OPEN CLUSTERS
    CANNON, RD
    [J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1970, 150 (01) : 111 - &
  • [7] CHIOSI C, 1992, ANNU REV ASTRON ASTR, V30, P235
  • [9] HST observations of the field star population in the Large Magellanic Cloud
    Elson, RAW
    Gilmore, GF
    Santiago, BX
    [J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1997, 289 (01) : 157 - 168
  • [10] FAGOTTO F, 1994, ASTRON ASTROPHYS SUP, V105, P29