J/A+A/645/A115 346 M31 star clusters and their parameters (Wang+, 2021)
Estimating ages and metallicities of M31 star clusters from LAMOST DR6.
Wang S., Chen B., Ma J.
<Astron. Astrophys. 645, A115 (2021)>
=2021A&A...645A.115W 2021A&A...645A.115W (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Abundances, [Fe/H] ; Photometry ; Optical
Keywords: galaxies: general - galaxies: star clusters: general -
galaxies: star clusters: individual: M31
Abstract:
Determining the metallicities and ages of M31 clusters is fundamental
to the study of the formation and evolution of M31 itself. The Large
Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has
carried out a systematic spectroscopic campaign of clusters and
candidates in M31.
We constructed a catalogue of 346 M31 clusters observed by LAMOST. By
combining the information of the LAMOST spectra and the multi-band
photometry, we developed a new algorithm to estimate the metallicities
and ages of these clusters.
We distinguish young clusters from old using random forest classifiers
based on a empirical training data set selected from the literature.
Ages of young clusters are derived from the spectral energy
distribution fits of their multi-band photometric measurements. Their
metallicities are estimated by fitting their observed spectral
principal components extracted from the LAMOST spectra with those from
the young metal-rich single stellar population (SSP) models. For old
clusters we built non-parameter random forest models between the
spectral principal components and/or multi-band colours and the
parameters of the clusters based on a training data set constructed
from the SSP models. The ages and metallicities of the old clusters
are then estimated by fitting their observed spectral principal
components extracted from the LAMOST spectra and multi-band colours
from the photometric measurements with the resultant random forest
models.
We derived parameters of 53 young and 293 old clusters in our
catalogue. Our resultant parameters are in good agreement with those
from the literature. The ages of ∼30 catalogued clusters and
metallicities of ∼40 sources are derived for the first time.
Description:
We select confirmed M31 star clusters and candidates from the
literature and match them with the LAMOST DR6. This yields a sample of
346 M31 clusters with LAMOST observations: 334 are confirmed clusters
from the previous works and 12 are new clusters with radial velocity
Vr←150km/s.
Table1 contains 346 M31 star clusters and their derived parameters
(ages and [Fe/H]), as well as their coordinates, multiband photometric
data. -999 represents that there is no corresponding value of the
source.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 402 346 Cluster names, positions and parameters
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Byte-by-byte Description of file:table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Name of the star cluster in the catalogue
14- 22 F9.6 deg RAdeg Right Ascension (J2000)
24- 32 F9.6 deg DEdeg Declination (J2000)
34- 41 F8.3 mag cmag ?=-999 BATC c magnitude
43- 50 F8.3 mag dmag ?=-999 BATC d magnitude
52- 59 F8.3 mag emag ?=-999 BATC e magnitude
61- 68 F8.3 mag fmag ?=-999 BATC f magnitude
70- 77 F8.3 mag gmag ?=-999 BATC g magnitude
79- 86 F8.3 mag hmag ?=-999 BATC h magnitude
88- 95 F8.3 mag imag ?=-999 BATC i magnitude
97-104 F8.3 mag jmag ?=-999 BATC j magnitude
106-113 F8.3 mag kmag ?=-999 BATC k magnitude
115-122 F8.3 mag mmag ?=-999 BATC m magnitude
124-131 F8.3 mag nmag ?=-999 BATC n magnitude
133-140 F8.3 mag omag ?=-999 BATC o magnitude
142-149 F8.3 mag pmag ?=-999 BATC p magnitude
151-158 F8.3 mag e_cmag ?=-999 BATC c magnitude error
160-167 F8.3 mag e_dmag ?=-999 BATC d magnitude error
169-176 F8.3 mag e_emag ?=-999 BATC e magnitude error
178-185 F8.3 mag e_fmag ?=-999 BATC f magnitude error
187-194 F8.3 mag e_gmag ?=-999 BATC g magnitude error
196-203 F8.3 mag e_hmag ?=-999 BATC h magnitude error
205-212 F8.3 mag e_imag ?=-999 BATC i magnitude error
214-221 F8.3 mag e_jmag ?=-999 BATC j magnitude error
223-230 F8.3 mag e_kmag ?=-999 BATC k magnitude error
232-239 F8.3 mag e_mmag ?=-999 BATC m magnitude error
241-248 F8.3 mag e_nmag ?=-999 BATC n magnitude error
250-257 F8.3 mag e_omag ?=-999 BATC o magnitude error
259-266 F8.3 mag e_pmag ?=-999 BATC p magnitude error
268-275 F8.3 mag uSmag ?=-999 SDSS u magnitude
277-284 F8.3 mag gSmag ?=-999 SDSS g magnitude
286-293 F8.3 mag rSmag ?=-999 SDSS r magnitude
295-302 F8.3 mag iSmag ?=-999 SDSS i magnitude
304-311 F8.3 mag zSmag ?=-999 SDSS z magnitude
313-320 F8.3 mag e_uSmag ?=-999 SDSS u magnitude error
322-329 F8.3 mag e_gSmag ?=-999 SDSS g magnitude error
331-338 F8.3 mag e_rSmag ?=-999 SDSS r magnitude error
340-347 F8.3 mag e_iSmag ?=-999 SDSS i magnitude error
349-356 F8.3 mag e_zSmag ?=-999 SDSS z magnitude error
358-362 F5.3 mag E(B-V) ?=-999 Dust reddening E(B-V)
364-371 F8.3 [yr] logAge ?=-999 Resultant age (log t) from this work
373-380 F8.3 [yr] e_logAge ?=-999 Uncertainty of the age
382-389 F8.3 [Sun] [Fe/H] ?=-999 Resultant metallicity ([Fe/H])
from this work
391-398 F8.3 [Sun] e_[Fe/H] ?=-999 Uncertainty of the metallicity
400 I1 --- RFclass [0/1] Classification of clusters from the
random forest classifiers
402 I1 --- Class [0/1] Final classification of clusters in the
current work
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Acknowledgements:
Shoucheng Wang, scwang(at)nao.cas.cn
(End) Patricia Vannier [CDS] 30-Nov-2020