2007A&A...469..529K


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.02CET19:40:14

2007A&A...469..529K - Astronomy and Astrophysics, volume 469, 529-537 (2007/7-2)

Multi-color photometry of the Galactic globular cluster M 75 = NGC 6864. A new sensitive metallicity indicator and the position of the horizontal branch in UV.

KRAVTSOV V., ALCAINO G., MARCONI G. and ALVARADO F.

Abstract (from CDS):

We carry out and analyze new multi-color photometry of the Galactic globular cluster (GC) M 75 in UBVI and focus on the brighter sequences of the color-magnitude diagram (CMD), with particular emphasis on their location in U-based CMD. Specifically, we study the level both of the horizontal (HB) and red giant branches (RGB) relative to the main-sequence turnoff (TO) in the U magnitude. Along with the presented photometry of M 75, we use our collection of photometric data on GCs belonging to the metal-poor range, [Fe/H]ZW←1.1dex, obtained from observations with different equipment, but calibrated by standard stars situated in the observed cluster fields. We confirm our earlier finding, and extend it to a larger magnitude range. We demonstrate that ΔUTOBHB expressing the difference in U magnitude between the TO point and the level of the blue HB, near its red boundary, of the metal-poor GCs observed with the EMMI camera of the NTT/ESO telescope is about 0.4-0.5mag smaller as compared to GCs observed with the 100'' telescope and 1.3m Warsaw telescope of the Las Campanas Observatory. At the same time, ΔUTORGB, the difference in U magnitude between the TO and RGB inflection (brightest) points, does not show such an apparent dependence on the characteristics of U filters used, but it depends on cluster metallicity. We have shown, for the first time, the dependence of the parameter ΔUTORGB on [Fe/H] and have estimated its analytical expression, by assuming a linear relation between the parameter and metallicity. Its slope, ΔUTORGB/Δ[Fe/H]∼1.2mag/dex, is approximately a factor of two steeper than that of the dependence of the RGB bump position in the V magnitude on metallicity. The asymptotic giant branch (AGB) clump and features of the RGB luminosity function (LF) of M 75 are also discussed.

Abstract Copyright:

Journal keyword(s): Galaxy: globular clusters: general - Galaxy: globular clusters: individual: M 75 - stars: population II

VizieR on-line data: <Available at CDS (J/A+A/469/529): m75phot.dat>

Nomenclature: Table 2: Cl* NGC 6864 KAM A (Nos A-D, G). Catalog: Cl* NGC 6864 KAM NNNN (Nos 1-2681).

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 19

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Number of rows : 19

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 ESO 28-19 Cl* 00 24 47 -72 47.7   11.6 12.05     ~ 133 0
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9702 1
3 NGC 288 GlC 00 52 45.24 -26 34 57.4   10 8.13     ~ 942 0
4 NGC 1841 GlC 04 45 23 -83 59.8   12.23 11.43     ~ 174 0
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15205 1
6 M 79 GlC 05 24 10.59 -24 31 27.3   9.21 8.16     ~ 730 0
7 M 80 GlC 16 17 02.41 -22 58 33.9           ~ 637 0
8 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2036 0
9 NGC 6397 GlC 17 40 42.09 -53 40 27.6   7.39 5.17     ~ 1821 1
10 NGC 6541 GlC 18 08 02.36 -43 42 53.6   8.06 7.32     ~ 332 1
11 NGC 6723 GlC 18 59 33.15 -36 37 56.1           ~ 440 0
12 NGC 6793 OpC 19 23 18 +22 08.4           ~ 28 0
13 M 75 GlC 20 06 04.841 -21 55 20.14     8.26     ~ 322 0
14 M 30 GlC 21 40 22.12 -23 10 47.5     7.10     ~ 940 0
15 Cl* NGC 6864 KAM B * ~ ~ 13.94 14.52 13.770   12.93 ~ 1 0
16 Cl* NGC 6864 KAM D * ~ ~ 14.72 15.25 14.240   13.2 ~ 1 0
17 Cl* NGC 6864 KAM G * ~ ~ 15.49 16.01 15.210   14.39 ~ 1 0
18 Cl* NGC 6864 KAM A * ~ ~ 13.74 14.37 13.650   12.81 ~ 1 0
19 Cl* NGC 6864 KAM C * ~ ~ 14.39 15.01 14.230   13.36 ~ 1 0

    Equat.    Gal    SGal    Ecl

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