Query : 2001A&A...371..921S

2001A&A...371..921S - Astronomy and Astrophysics, volume 371, 921-931 (2001/6-1)

On the white dwarf distances to galactic globular clusters.


Abstract (from CDS):

We analyze in detail various possible sources of systematic errors on the distances of globular clusters derived by fitting a local template DA white dwarf sequence to the cluster counterpart (the so-called WD-fitting technique). We find that the unknown thickness of the hydrogen layer of white dwarfs in clusters plays a non negligible role. For reasonable assumptions - supported by the few sparse available observational constraints - about the unknown mass and thickness of the hydrogen layer for the cluster white dwarfs, a realistic estimate of the systematic error on the distance is within ±0.10mag. However, particular combinations of white dwarf masses and envelope thicknesses - which at present cannot be excluded a priori - could produce larger errors. Contamination of the cluster DA sequence by non-DA white dwarfs introduces a very small systematic error of about -0.03mag in the MV/(V-I) plane, but in the MV/(B-V) plane the systematic error amounts to ~+0.20mag. Contamination by white dwarfs with helium cores should not influence appreciably the WD-fitting distances. Finally, we obtain a derivative Δ(m-M)V/ΔE(B-V)~-5.5 for the WD-fitting distances, which is very similar to the dependence found when using the Main Sequence fitting technique.

Abstract Copyright:

Journal keyword(s): distance scale - globular clusters: general - stars: white dwarfs

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NGC 104 GlC 00 24 05.359 -72 04 53.20     4.09     ~ 3796 0
2 * alf CMa B WD* 06 45 09.3041925037 -16 43 00.724740067   8.41 8.44     DA1.9 526 1
3 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 2036 0
4 NGC 6752 GlC 19 10 52.11 -59 59 04.4           ~ 1934 0

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