J/MNRAS/451/3400 Star clusters in M33 (Beasley+, 2015)
Evidence for temporal evolution in the M33 disc as traced by its star clusters.
Beasley M.A., San Roman I, Gallart G., Sarajedini A., Aparicio A.
<Mon. Not. R. Astron. Soc. 451, 3400 (2015)>
=2015MNRAS.451.3400B 2015MNRAS.451.3400B
ADC_Keywords: Clusters, open ; Clusters, globular ; Galaxies, nearby
Keywords: Local Group - galaxies: star clusters: general
Abstract:
We present precision radial velocities and stellar population
parameters for 77 star clusters in the Local Group galaxy M33. Our
Gran Telescopio de Canarias and William Herschel Telescope
observations sample both young, massive clusters and known/candidate
globular clusters (GCs), spanning ages ∼106-1010yr, and
metallicities, [M/H]~-1.7 to solar.
The cluster system exhibits an age-metallicity relation; the youngest
clusters are the most metal rich. When compared to HI data, clusters
with [M/H]~-1.0 and younger than ∼4Gyr are clearly identified as
a disc population. The clusters show evidence for strong time
evolution in the disc radial metallicity gradient
(d[M/H]dt/dR=0.03dex/kpc/Gyr). The oldest clusters have stronger, more
negative gradients than the youngest clusters in M33. The clusters
also show a clear age-velocity dispersion relation. The line-of-sight
velocity dispersions of the clusters increases with age similar to
Milky Way open clusters and stars. The general shape of the relation
is reproduced by disc heating simulations, and the similarity between
the relations in M33 and the Milky Way suggests that heating by
substructure and cooling of the interstellar medium both play a role
in shaping this relation. We identify 12 'classical' GCs, six of which
are newly identified GC candidates. The GCs are more metal rich than
Milky Way halo clusters, and show weak rotation. The inner (R<4.5kpc)
GCs exhibit a steep radial metallicity gradient
(d[M/H]/dR=-0.29±0.11dex/kpc) and an exponential-like surface
density profile. We argue that these inner GCs are thick disc rather
than halo objects.
Description:
Basic and derived data for M33 cluster sample. This is the full table
2 corresponding to the abbreviated one in the online journal article.
Previously confirmed candidates (identified by radial velocities or
high-resolution imaging) were observed using OSIRIS on the GTC in
long-slit mode during semesters 2010B-2012A.
Previously identified star clusters and star cluster candidates
identified by San Roman et al. (2010ApJ...720.1674S 2010ApJ...720.1674S, Cat.
J/ApJ/720/1674) were observed using the WYFFOS/AF2 multifibre
instrument on the WHT in La Palma.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 91 77 Co-ordinates, velocities, ages and
metallicities of 77 M33 star clusters
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See also:
J/AJ/134/447 : Catalog of star cluster candidates in M 33 (Sarajedini+, 2007)
J/ApJ/720/1674 : CFHT M33 extended sources catalog (San Roman+, 2010)
J/MNRAS/426/2427 : Structural parameters of M33 clusters (San Roman+, 2012)
J/ApJS/211/22 : Updated photometry for star clusters in M33 (Fan+, 2014)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- ID Cluster ID (1)
8- 9 I2 h RAh Right ascension (J2000.0)
11- 12 I2 min RAm Right ascension (J2000.0)
14- 18 F5.2 s RAs Right ascension (J2000.0)
20- 21 I2 deg DEd Declination (J2000.0)
23- 24 I2 arcmin DEm Declination (J2000.0)
26- 30 F5.2 arcsec DEs Declination (J2000.0)
32- 37 F6.3 Gyr Age [0.009/15.8] Cluster age
39- 43 F5.3 Gyr e_Age [0.001/3.8] Uncertainty in age
45- 49 F5.2 [Sun] [M/H] [-1.8/0.2] Cluster metallicity (in dex)
51- 54 F4.2 [Sun] e_[M/H] [0.1/0.32] Uncertainty in metallicity (in dex)
56- 59 I4 km/s HRV [-262/-21] Heliocentric radial velocity
61- 62 I2 km/s e_HRV [2/30] Uncertainty in radial velocity
64- 67 I4 km/s VHI [-261/-100] HI velocity at cluster location
69- 73 F5.1 deg PA [0/360] Position angle (East of North) of cluster
75- 91 A17 --- Notes Comments on cluster properties
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Note (1): Cluster names are from:
SRNNNN : San Roman et al. 2010ApJ...720.1674S 2010ApJ...720.1674S, Cat. J/ApJ/720/1674,
<[SSA2010] NNNN> in Simbad
SMNNNN : Sarajedini & Mancone, 2007AJ....134..447S 2007AJ....134..447S, Cat. J/AJ/134/447
<[SM2007] NNN> in Simbad
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Acknowledgements:
Michael A. Beasley, beasley(at)iac.es
(End) Michael A. Beasley [IAC, Spain], Patricia Vannier [CDS] 19-Aug-2015