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

Journal Article · Sun Jan 10 00:00:00 EST 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/708/2/L74; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21301412

Bono, G; Di Cecco, A; Sanna, N; Buonanno, R ^[1]; Stetson, P B ^[2]; VandenBerg, D A ^[3]; Calamida, A; Amico, P; Marchetti, E; D'Odorico, S; Gilmozzi, R ^[4]; Dall'Ora, M ^[5]; Iannicola, G; Caputo, F; Corsi, C E; Ferraro, I ^[6]; Monelli, M ^[7]; Walker, A R ^[8]; Zoccali, M ^[9]

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1. Department of Physics, UniToV, via della Ricerca Scientifica 1, 00133 Rome (Italy)
2. DAO-HIA, NRC, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)
3. Department of Physics and Astronomy, UVIC, Victoria, BC V8W 3P6 (Canada)
4. ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei Munchen (Germany)
5. INAF-OACN, via Moiariello 16, 80131 Napoli (Italy)
6. INAF-OAR, via Frascati 33, Monte Porzio Catone, Rome (Italy)
7. IAC, Calle Via Lactea, E38200 La Laguna, Tenerife (Spain)
8. CTIO-NOAO, Casilla 603, La Serena (Chile)
9. PUC, Dept. Astronomia y Astrofisica, Casilla 306, Santiago 22 (Chile)

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 ({approx}0.05 mag) NIR and optical-NIR colors than observed for magnitudes fainter than the MSK.

• OSTI ID: 21301412
• Journal Information: Astrophysical Journal Letters, Vol. 708, Issue 2; Other Information: DOI: 10.1088/2041-8205/708/2/L74; Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ABSORPTION
COLOR
HYDROGEN
STAR CLUSTERS
STAR EVOLUTION
STARS
TELESCOPES