The absolute age of the globular cluster M15 using near-infrared adaptive optics images from PISCES/LBT

Journal Article · Sat Oct 10 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/812/1/25· OSTI ID:22882500

Monelli, M. ^[1]; Testa, V.; Bono, G.; Ferraro, I.; Iannicola, G.; Boutsia, K.; Carini, R. ^[2]; Fiorentino, G.; Arcidiacono, C.; Massari, D.; Cresci, G. ^[3]; Briguglio, R.; Busoni, L.; Esposito, S.; Fini, L. ^[4]; Close, L.; Kulesa, C. ^[5]; Fumana, M. ^[6]; Guerra, J. C.; others, and

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1. Instituto de Astrofísica de Canarias, La Laguna, Tenerife (Spain)
2. INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monteporzio Catone (Italy)
3. INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
4. INAF-Osservatorio Astronomico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy)
5. Steward Observatory, Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States)
6. INAF-IASF, via E. Bassini 15, I-20133 Milano (Italy)

We present deep near-infrared J, K{sub s} photometry of the old, metal-poor Galactic globular cluster M15 obtained with images collected with the LUCI1 and PISCES cameras available at the Large Binocular Telescope (LBT). We show how the use of First Light Adaptive Optics (FLAO) system coupled with the PISCES camera allows us to improve the limiting magnitude by ∼2 mag in K{sub s}. By analyzing archival Hubble Space Telescope data, we demonstrate that the quality of the LBT/PISCES color–magnitude diagram is fully comparable with analogous space-based data. The smaller field of view is balanced by the shorter exposure time required to reach a similar photometric limit. We investigated the absolute age of M15 by means of two methods: (i) by determining the age from the position of the main-sequence turnoff (MSTO), and (ii) by the magnitude difference between the MSTO and the well-defined knee detected along the faint portion of the MS. We derive consistent values of the absolute age of M15, that is, 12.9 ± 2.6 Gyr and 13.3 ± 1.1 Gyr, respectively.

• OSTI ID: 22882500
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 812; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPARATIVE EVALUATIONS
GALAXY CLUSTERS
OPTICS
PHOTOMETRY
SPACE
TELESCOPES