J/AJ/124/1418 Radio-optical identification of star clusters (Whitmore+, 2002)
What fraction of the young clusters in the Antennae galaxies are "missing"?
Whitmore B.C., Zhang Q.
<Astron. J. 124, 1418 (2002)>
=2002AJ....124.1418W 2002AJ....124.1418W
ADC_Keywords: Clusters, open ; Radio sources
Keywords: galaxies: individual (NGC 4038, NGC 4039) - galaxies: interactions -
galaxies: star clusters
Abstract:
A reexamination of the correspondence between 6cm radio continuum
sources and young star clusters in the Antennae galaxies indicates
that ∼85% of the strong thermal sources have optical counterparts,
once the optical image is shifted 1.2" to the southwest. A sample of
37 radio-optical matches are studied in detail, showing correlations
between radio properties (i.e., total flux and spectral index) and a
variety of optical characteristics (i.e., intrinsic cluster
brightness, Hα flux and equivalent width, extinction, and
cluster ages). There is a strong correlation between the radio flux
and the intrinsic optical brightness.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 81 45 Matches between radio and optical positions
notes.dat 80 38 Individual notes to table 2
table3.dat 59 44 *Various parameters for radio-optical matches
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Note on table3.dat: Object 1 was omitted from the sample
since it is the center of NGC 4039, rather than a cluster.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- [WZ2002] ? Sequential number of the Object
4- 8 I5 --- HST HST number (G1)
9 A1 --- n_HST [*] Note on HST number (1)
11- 15 A5 --- NRadio Radio name (G2)
17- 18 I2 h RAh ? Radio right ascension (J2000.0) (3)
20- 21 I2 min RAm ? Radio right ascension (J2000.0)
23- 27 F5.2 s RAs ? Radio right ascension (J2000.0)
29 A1 --- DE- Declination sign (J2000.0)
30- 31 I2 deg DEd ? Radio declination (J2000.0)
33- 34 I2 arcmin DEm ? Radio declination (J2000.0)
36- 40 F5.2 arcsec DEs ? Radio declination (J2000.0)
42- 46 F5.2 arcsec oRA Offset in right ascension,
radio minus HST position
48- 52 F5.2 arcsec oDE Offset in declination, radio minus HST position
54- 58 F5.2 mag Vmag V magnitude (4)
60- 64 F5.2 mag V-I V-I colour index (4)
66- 69 I4 mJy S6cm ? Flux density at 6cm (3)
70 A1 --- n_S6cm [*] *: S6cm is an upper limit, see note in
notes.dat file
72- 76 F5.2 --- Sp+Index ? Spectral index (3)
78- 81 F4.2 --- e_Sp+Index ? rms uncertainty on Sp+Index
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Note (1): *: Values from the Hα-selected sample. See text for details.
Note (3): From Neff & Ulvestad, 2000AJ....120..670N 2000AJ....120..670N
Note (4): From Whitmore et al., 1999AJ....118.1551W 1999AJ....118.1551W. Uncorrected for extinction.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- NRadio Radio name
7- 80 A74 --- Note Text of the note
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- [WZ2002] ? Sequential number of the Object
4- 8 I5 --- HST HST number (G1)
9 A1 --- n_HST [*] Note on HST (1)
11- 15 A5 --- NRadio Radio name (G2)
17- 21 F5.2 mag (V-I)c Corrected (V-I) colour index (2)
23- 26 F4.2 mag AV Absorption in V band
28- 33 F6.2 mag VMAG Absolute V magnitude (3)
35- 38 F4.2 [0.1nm] logHa Hα equivalent width (3)
40- 43 F4.2 [0.1nm] logHar Total Hα equivalent width, centered at
the radio position, with a radius 0.5" (3)
45- 47 F3.1 Myr Age Age
49 I1 --- Qual Quality flag (4)
51- 53 F3.1 [solMass] Mass Mass of the cluster, log scale (5)
56- 59 A4 --- Com Comments
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Note (1): *: Values from the Hα-selected sample. See text for details.
Note (2): Corrected for the presence of emission lines in the V band (see text).
Uncorrected for extinction.
Note (3): Corrected for extinction.
Note (4): From 1, highest quality (i.e., all four age indicators are in
agreement) to 3, lowest quality (i.e., some of the age indicators
are in serious disagreement with other age indicators).
Note (5): Photometric mass determined from VMAG, Age, and the solar-metallicity
Bruzual and Charlot (1993ApJ...405..538B 1993ApJ...405..538B) model. See text for details.
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Global notes:
Note (G1): Based on full list of 14,000 point sources (including both clusters
and stars) from Whitmore et al. (1999AJ....118.1551W 1999AJ....118.1551W), placed in
order of increasing right ascension. Note that this system is being
introduced in the current paper; the numbers do not match the ID
numbers used in earlier papers. A full list of the new ID numbers,
cross-referenced with the old list, is available on request by
contacting the author
Note (G2): Nomenclature note:
1-5 = [NU2000] 1 5 in Simbad
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History:
From electronic version of the journal
(End) James Marcout, Patricia Bauer [CDS] 08-Nov-2002