J/ApJ/559/851 Young star cluster candidates in M31 (Williams+, 2001)
Identification and analysis of young star cluster candidates in M31.
Williams B.F., Hodge P.W.
<Astrophys. J. 559, 851 (2001)>
=2001ApJ...559..851W 2001ApJ...559..851W
ADC_Keywords: Associations, stellar ; Reddening
Keywords: galaxies: individual (M31) - galaxies: spiral -
galaxies: stellar content - open clusters and associations: general
Abstract:
We present a method for finding clusters of young stars in M31 using
broadband WFPC2 data from the HST data archive. Applying our
identification method to 13 WFPC2 fields, covering an area of
60arcmin2, has revealed 79 new candidate young star clusters in
these portions of the M31 disk. Most of these clusters are small
(≲5pc), young (∼10-200Myr) star groups located within large OB
associations. We have estimated the reddening values and the ages of
each candidate individually by fitting isochrones to the stellar
photometry. We provide a catalog of the candidates including rough
approximations of their reddenings and ages. We also look for patterns
of cluster formation with galactocentric distance, but our rough
estimates are not precise enough to reveal any clear patterns.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 55 67 Data obtained from the HST data archive used
for the Cluster Survey
table4.dat 87 80 Catalog of positions, galactocentric distances,
age estimates, reddening values, and search
radii for M31 young star cluster candidates
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See also:
J/ApJS/98/595 : OB associations in M31 (Hill+ 1995)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Field Field number
4- 7 I4 --- NProp Proposal number
9- 18 A10 "YYYY/MM/DD" ObsDate Observation Date
20- 21 I2 h RAh Right ascension (J2000.0)
23- 24 I2 min RAm Right ascension (J2000.0)
26- 30 F5.2 s RAs Right ascension (J2000.0)
32 A1 --- DE- Declination sign (J2000.0)
33- 34 I2 deg DEd Declination (J2000.0)
36- 37 I2 arcmin DEm Declination (J2000.0)
39- 42 F4.1 arcsec DEs Declination (J2000.0)
45- 49 A5 --- Filter Filter
52- 55 I4 s Texp Exposition time
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- --- [M31SCC]
8- 22 A15 --- M31SCC Identification name, JHHMMSS+DDMMSSA
24- 32 A9 --- Name Other names (1)
34- 35 I2 h RAh Right Ascension (J2000)
37- 38 I2 min RAm Right Ascension (J2000)
40- 44 F5.2 s RAs Right Ascension (J2000)
46 A1 --- DE- Declination sign (J2000)
47- 48 I2 deg DEd Declination (J2000)
50- 51 I2 arcmin DEm Declination (J2000)
53- 57 F5.2 arcsec DEs Declination (J2000)
59- 63 F5.2 kpc Dist Galactocentric distance
65- 68 F4.2 [yr] logAge Log of the cluster age
70- 73 F4.2 [yr] e_logAge Uncertainty in logAge
75- 78 F4.2 mag E(B-V) The E(B-V) reddening value
80- 83 F4.2 mag e_E(B-V) Uncertainty in E(B-V)
85- 86 I2 pc Rad Automated search routine radius (2)
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Note (1): Other names:
G42 = refers to the globular cluster catalog of Sargent et al.
(1977AJ.....82..947S 1977AJ.....82..947S); SKHB NNN in Simbad
[H81] B-202 = identified in Hodge (1981, Atlas of the Andromeda galaxy,
Seattle: Univ. Washington Press, 1981).
Note (2): Using this radius the algorithm searched for overdensities over
areas of (πRad2).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 14-Jan-2002