Query : 2002A&A...390..961A

2002A&A...390..961A - Astronomy and Astrophysics, volume 390, 961-965 (2002/8-2)

The white dwarf cooling sequence in the old open cluster NGC 188.


Abstract (from CDS):

We develop the white dwarf luminosity function (LF) of the old open cluster NGC188 in order to determine a lower limit to the age of the cluster by using the faint end of the cooling sequence. To produce an extensive sequence of the cooling white dwarfs we imaged four contiguous HST-WFPC2 fields in the center of the cluster in the F555W and F814W filters. After imposing selection criteria on the detected objects we found a white dwarf cooling sequence (down to V≃26.5) including 28 candidate white dwarfs in the cluster. The exposures are not deep enough to reach the end of this sequence, but the results of our analysis allow us to establish a lower limit to the age of the cluster independently of the isochrone fit to the cluster turnoff. The most ancient white dwarfs found are ≃4Gyr old, an age that is set solely by the photometric limit of our data. Classical methods provide an estimate of ≃7Gyr (Sarajedini et al., 1999AJ....118.2894S).

Abstract Copyright:

Journal keyword(s): open clusters and associations: individual: NGC 188 - stars: white dwarfs - stars: luminosity function

VizieR on-line data: <Available at CDS (J/A+A/390/961): catalog.dat>

Nomenclature: Catalog: [ARL2002] NNNNNN N=223.

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

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NGC 188 OpC 00 47 11.5 +85 14 38           ~ 905 0
2 Cl Berkeley 17 OpC 05 20 31.2 +30 34 26           ~ 171 0
3 NGC 6791 OpC 19 20 53.0 +37 46 41   10.52 9.5     ~ 1018 0

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