2014A&A...563A..76M


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST14:52:33

2014A&A...563A..76M - Astronomy and Astrophysics, volume 563A, 76-76 (2014/3-1)

Deriving metallicities from calcium triplet spectroscopy in combination with near-infrared photometry.

MAURO F., MONI BIDIN C., GEISLER D., SAVIANE I., DA COSTA G.S., GORMAZ-MATAMALA A.C., VASQUEZ S., CHENE A.-N., COHEN R. and DIAS B.

Abstract (from CDS):

When they are established with sufficient precision, the ages, metallicities and kinematics of Galactic globular clusters (GGCs) can shed much light on the dynamical and chemical evolution of the Galactic halo and bulge. While the most fundamental way of determining GC abundances is by means of high-resolution spectroscopy, in practice this method is limited to only the brighter stars in the nearest and less reddened objects. This restriction has, over the years, led to the development of a large number of techniques that measure the overall abundance indirectly from parameters that correlate with overall metallicity. One of the most efficient methods is measuring the equivalent width (EW) of the calcium II triplet (CaT) at λ≃8500Å in red giants, which are corrected for the luminosity and temperature effects using the V magnitude differences from the horizontal branch (HB). We establish a similar method in the near-infrared (NIR), by combining the power of the differential magnitudes technique with the advantages of NIR photometry to minimize differential reddening effects. We used the Ks magnitude difference between the star and the reddest part of the HB (RHB) or of the red clump (RC) to generate reduced equivalent widths (rEW) from previously presented datasets. Then we calibrated these rEW against three previously reported different metallicity scales; one of which we corrected using high-resolution spectroscopic metallicities. We calculated the calibration relations for the two datasets and the three metallicity scales and found that they are approximately equivalent, with almost negligible differences. We compared our NIR calibrations with the corresponding optical ones, and found them to be equivalent, which shows that the luminosity-corrected rEW using the Ks magnitude is compatible with the one obtained from the V magnitude. We then used the metallicities obtained from the calibration to investigate the internal metallicity distributions of the GCs. We have established that the ([Fe/H]:rEW) relation is independent of the magnitude used for the luminosity correction and find that the calibration relations change only slightly for different metallicity scales. The CaT technique using NIR photometry is thus a powerful tool to derive metallicities. In particular, it can be used to study the internal metallicity spread of a GC. We confirm the presence of at least two metallicity populations in NGC6656 and find that several other GCs present peculiar metallicity distributions.

Abstract Copyright:

Journal keyword(s): stars: abundances - globular clusters: general - stars: kinematics and dynamics

VizieR on-line data: <Available at CDS (J/A+A/563/A76): table1.dat table8.dat>

Nomenclature: Table 8: [MMG2014] JDDD.dddddd+DD.dddddd N=443.

Status at CDS:   Acronym for new objects described in the dictionary of nomenclature and being created in SIMBAD. // Tables of objects will be appraised for possible ingestion in SIMBAD.

Simbad objects: 36

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Number of rows : 36

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10902 1
2 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5665 1
3 IRAS 09110-6439 GlC 09 12 03.10 -64 51 48.6   7.77 5.69     ~ 1244 0
4 NGC 3201 GlC 10 17 36.82 -46 24 44.9   9.18 8.24     ~ 722 0
5 NGC 4372 GlC 12 25 45.43 -72 39 32.7   10.86 9.85     ~ 263 0
6 M 68 GlC 12 39 27.98 -26 44 38.6   10.26 7.96     ~ 876 0
7 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1676 0
8 NGC 6139 GlC 16 27 39.987 -38 50 57.03   11.03 9.68     ~ 179 0
9 M 10 GlC 16 57 09.05 -04 06 01.1     4.98     ~ 683 0
10 NGC 6325 GlC 17 17 59.27 -23 45 57.7   11.49       ~ 140 0
11 NGC 6356 GlC 17 23 34.99 -17 48 46.9   10.01 7.42     ~ 320 1
12 ESO 455-11 GlC 17 31 05.20 -29 58 54.0           ~ 131 0
13 NGC 6380 GlC 17 34 28.00 -39 04 09.0           ~ 97 0
14 NGC 6397 GlC 17 40 42.09 -53 40 27.6   7.39 5.17     ~ 1798 1
15 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11533 0
16 NGC 6440 GlC 17 48 52.67 -20 21 34.5   12.01 10.10     ~ 469 1
17 NGC 6441 GlC 17 50 13.06 -37 03 05.2   9.26 8.00     ~ 768 0
18 NAME Baade Window reg 18 03.5 -30 01           ~ 528 3
19 NGC 6522 GlC 18 03 34.08 -30 02 02.3   10.68 9.48     ~ 455 1
20 NGC 6528 GlC 18 04 49.61 -30 03 20.8   12.12 10.65     ~ 465 0
21 NGC 6544 GlC 18 07 20.58 -24 59 50.4   11.36 9.90     ~ 233 0
22 NGC 6541 GlC 18 08 02.36 -43 42 53.6   8.06 7.32     ~ 321 1
23 NGC 6553 GlC 18 09 15.68 -25 54 27.9   9.08       ~ 535 0
24 NGC 6558 GlC 18 10 18.38 -31 45 48.6   12.39 11.29     ~ 179 0
25 IC 1276 GlC 18 10 44.26 -07 12 27.3           ~ 100 0
26 NGC 6569 GlC 18 13 38.88 -31 49 35.2   10.78 9.47     ~ 188 0
27 NGC 6624 GlC 18 23 40.51 -30 21 39.7           ~ 774 1
28 M 28 GlC 18 24 32.89 -24 52 11.4           ~ 662 0
29 NGC 6638 GlC 18 30 56.25 -25 29 47.1   10.81 9.68     ~ 193 0
30 M 69 GlC 18 31 23.10 -32 20 53.1   9.32 8.31     ~ 405 1
31 M 22 GlC 18 36 23.94 -23 54 17.1   7.16 6.17     ~ 1217 0
32 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 758 0
33 M 71 GlC 19 53 46.49 +18 46 45.1   7.91 6.1     ~ 1024 0
34 M 15 GlC 21 29 58.33 +12 10 01.2   3       ~ 2907 0
35 M 30 GlC 21 40 22.12 -23 10 47.5     7.10     ~ 913 0
36 NAME Galactic Bulge reg ~ ~           ~ 3387 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-14:52:33

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