2009A&A...493..539M


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.26CET18:29:52

2009A&A...493..539M - Astronomy and Astrophysics, volume 493, 539-546 (2009/1-2)

MCAO near-IR photometry of the globular cluster NGC 6388: MAD observations in crowded fields.

MORETTI A., PIOTTO G., ARCIDIACONO C., MILONE A.P., RAGAZZONI R., FALOMO R., FARINATO J., BEDIN L.R., ANDERSON J., SARAJEDINI A., BARUFFOLO A., DIOLAITI E., LOMBINI M., BRAST R., DONALDSON R., KOLB J., MARCHETTI E. and TORDO S.

Abstract (from CDS):

Deep photometry of crowded fields, such as Galactic globular clusters, is severely limited by the resolution of ground-based telescopes. On the other hand, the Hubble Space Telescope does not have the near-infrared (NIR) filters needed to allow large color baselines. In this work we demonstrate how ground based observations can reach the required resolution when using Multi-Conjugated Adaptive Optic (MCAO) devices in the NIR, such as the experimental infrared camera (MAD) available on the VLT. This is particularly important since these corrections are planned to be available on all ground-based telescopes in the near future. We demonstrate this by combining the infrared photometry obtained by MAD/VLT with ACS/HST optical photometry of our scientific target, the bulge globular cluster NGC 6388, in which we imaged two fields. In particular, we constructed color-magnitude diagrams with an extremely wide color baseline in order to investigate the presence of multiple stellar populations in this cluster. From the analysis of the external field, observed with better seeing conditions, we derived the deepest optical-NIR CMD of NGC 6388 to date. The high-precision photometry reveals that two distinct sub-giant branches are clearly present in this cluster. We also use the CMD from the central region to estimate the distance [(m-M)o=15.33] and the reddening (E(B-V)=0.38) for this cluster. We estimate the age to be (∼11.5±1.5Gyr). The large relative-age error reflects the bimodal distribution of the SGB stars. This study clearly demonstrates how MCAO correction in the NIR bands implemented on ground based telescopes can complement the high-resolution optical data from HST.

Abstract Copyright:

Journal keyword(s): stars: Hertzsprung-Russell (HR) and C-M diagrams - galaxy: globular clusters: general - stars: late-type

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3615 0
2 Feige 16 * 01 54 34.6343481929 -06 45 59.686242437 12.410 12.397 12.405 12.412 12.409 A0 28 0
3 NGC 1851 GlC 05 14 06.76 -40 02 47.6   8.80 7.23     ~ 1267 0
4 NGC 2808 GlC 09 12 03.10 -64 51 48.6   7.77 5.69     ~ 1276 0
5 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3071 0
6 NGC 6388 GlC 17 36 17.461 -44 44 08.34   7.40       ~ 827 1
7 NGC 6441 GlC 17 50 13.06 -37 03 05.2   9.26 8.00     ~ 788 0
8 NAME Galactic Bulge reg ~ ~           ~ 3531 0

    Equat.    Gal    SGal    Ecl

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