ON A NEW NEAR-INFRARED METHOD TO ESTIMATE THE ABSOLUTE AGES OF STAR CLUSTERS: NGC 3201 AS A FIRST TEST CASE

被引：55

作者：

Bono, G. ^{[1
,2
]}

Stetson, P. B. ^{[3
]}

VandenBerg, D. A. ^{[4
]}

Calamida, A. ^{[5
]}

Dall'Ora, M. ^{[6
]}

Iannicola, G. ^{[2
]}

Amico, P.

Di Cecco, A. ^{[1
]}

Marchetti, E. ^{[5
]}

Monelli, M. ^{[7
]}

Sanna, N. ^{[1
]}

Walker, A. R. ^{[8
]}

Zoccali, M. ^{[9
]}

Buonanno, R. ^{[1
,10
]}

Caputo, F. ^{[2
]}

Corsi, C. E. ^{[2
]}

Degl'Innocenti, S. ^{[11
,12
]}

D'Odorico, S. ^{[5
]}

Ferraro, I. ^{[2
]}

Gilmozzi, R. ^{[5
]}

Melnick, J. ^{[5
]}

Nonino, M. ^{[13
]}

Ortolani, S. ^{[14
]}

Piersimoni, A. M. ^{[15
]}

Moroni, P. G. Prada ^{[11
,12
]}

Pulone, L. ^{[2
]}

Romaniello, M. ^{[5
]}

Storm, J. ^{[16
]}

机构：

[1] UniToV, Dept Phys, I-00133 Rome, Italy

[2] INAF OAR, Rome, Italy

[3] NRC, DAO HIA, Victoria, BC V9E 2E7, Canada

[4] UVIC, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada

[5] ESO, D-85748 Garching, Germany

[6] INAF OACN, I-80131 Naples, Italy

[7] IAC, E-38200 Tenerife, Spain

[8] CTIO NOAO, La Serena, Chile

[9] PUC, Dept Astron & Astrofis, Santiago 22, Chile

[10] ESRIN, ASDC, ASI Sci Data Ctr, I-00044 Frascati, Italy

[11] Univ Pisa, Dept Phys, I-56127 Pisa, Italy

[12] Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy

[13] INAF OAT, I-40131 Trieste, Italy

[14] Univ Padua, Dept Astron, I-35122 Padua, Italy

[15] INAF OACTe, I-64100 Teramo, Italy

[16] AIP, D-14482 Potsdam, Germany

来源：

ASTROPHYSICAL JOURNAL LETTERS | 2010年 / 708卷 / 02期

关键词：

globular clusters: individual (NGC3201); stars: evolution; stars: fundamental parameters; GLOBULAR-CLUSTERS; METALLICITY SCALE; GALACTIC BULGE; MASS FUNCTION; PHOTOMETRY; DIFFUSION; ABUNDANCE; NGC-3201; ATMOSPHERES; DISTANCES;

D O I：

10.1088/2041-8205/708/2/L74

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present a new method to estimate the absolute ages of stellar systems. This method is based on the difference in magnitude between the main-sequence turnoff (MSTO) and a well-defined knee located along the lower main sequence (MSK). This feature is caused by the collisionally induced absorption of molecular hydrogen, and it can easily be identified in near-infrared (NIR) and in optical-NIR color-magnitude diagrams of stellar systems. We took advantage of deep and accurate NIR images collected with the Multi-Conjugate Adaptive Optics Demonstrator temporarily available on the Very Large Telescope and of optical images collected with the Advanced Camera for Surveys Wide Field Camera on the Hubble Space Telescope and with ground-based telescopes to estimate the absolute age of the globular NGC 3201 using both the MSTO and the Delta(MSTO-MSK). We have adopted a new set of cluster isochrones, and we found that the absolute ages based on the two methods agree to within 1 sigma. However, the errors of the ages based on the Delta(MSTO-MSK) method are potentially more than a factor of 2 smaller, since they are not affected by uncertainties in cluster distance or reddening. Current isochrones appear to predict slightly bluer (approximate to 0.05 mag) NIR and optical-NIR colors than observed for magnitudes fainter than the MSK.

引用

页码：L74 / L79

页数：6

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