J/MNRAS/476/1213 Ages for stars in 19 clusters (Getman+, 2018)
Intracluster age gradients in numerous young stellar clusters.
Getman K.V., Feigelson E.D., Kuhn M.A., Bate M.R., Broos P.S., Garmire G.P.
<Mon. Not. R. Astron. Soc., 476, 1213-1223 (2018)>
=2018MNRAS.476.1213G 2018MNRAS.476.1213G (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, ages
Keywords: stars: early-type - stars: formation - stars: pre-main sequence -
open clusters and associations: general - infrared: stars -
X-rays: stars
Abstract:
The pace and pattern of star formation leading to rich young stellar
clusters is quite uncertain. In this context, we analyse the spatial
distribution of ages within 19 young (median t≤3Myr on the Siess et
al. time-scale), morphologically simple, isolated, and relatively rich
stellar clusters. Our analysis is based on young stellar object (YSO)
samples from the Massive Young Star-Forming Complex Study in Infrared
and X-ray and Star Formation in Nearby Clouds surveys, and a new
estimator of pre-main sequence (PMS) stellar ages, AgeJX, derived
from X-ray and near-infrared photometric data. Median cluster ages are
computed within four annular subregions of the clusters. We confirm
and extend the earlier result of Getman et al. (2014ApJ...787..108G 2014ApJ...787..108G,
Cat. J/ApJ/787/108; 2014ApJ...787..109G 2014ApJ...787..109G. Cat. J/ApJ/787/109): 80 per
cent of the clusters show age trends where stars in cluster cores are
younger than in outer regions. Our cluster stacking analyses establish
the existence of an age gradient to high statistical significance in
several ways. Time-scales vary with the choice of PMS evolutionary
model; the inferred median age gradient across the studied clusters
ranges from 0.75 to 1.5Myr/pc. The empirical finding reported in the
present study - late or continuing formation of stars in the cores of
star clusters with older stars dispersed in the outer regions - has a
strong foundation with other observational studies and with the
astrophysical models like the global hierarchical collapse model of
Vazquez-Semadeni et al. (2017MNRAS.467.1313V 2017MNRAS.467.1313V).
Description:
Among the 141 MYStIX (Kuhn et al., 2014ApJ...787..107K 2014ApJ...787..107K, Cat.
J/ApJ/787/107) and 52 SFiNCs (Getman et al., 2018, MNRAS, in prep.)
clusters that are identified by an objective likelihood-based
statistical procedure (Kuhn et al. 2014ApJ...787..107K 2014ApJ...787..107K), we select the
ones that : (1) have a simple morphology (a single dense core
surrounded by a sparser halo); (2) are relatively isolated (without or
with only weak secondary sub-clusters present in their vicinity); 3)
and have a relatively high number of stars with available age
estimates. A total of 19 clusters, with 2487 AgeJX stars, satisfy
these criteria.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 56 2487 AgeJX Stars. All MYStIX and SFiNCs stars with
available age estimates across the 19 clusters
of interest
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See also:
J/ApJ/787/108 : Age estimates for massive SFR stellar populations
(Getman+, 2014)
J/ApJ/787/109 : Age estimates for NGC 2024 and ONC stars (Getman+, 2014)
J/ApJS/209/32 : Probable young stars in the MYStIX project (Broos+, 2013)
J/ApJS/229/28 : SFiNCs: X-ray, IR and membership catalogs (Getman+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Region Star-forming region name (1)
12- 30 A19 --- Source Source name (HHMMSS.ss+DDMMSS.sa) (2)
32- 41 F10.6 deg RAdeg Right ascension (J2000)
43- 52 F10.6 deg DEdeg Declination (J2000)
54- 56 F3.1 Myr AgeJX Stellar age estimated using the AgeJX method
of Getman et al. (2014ApJ...787..108G 2014ApJ...787..108G)
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Note (1): Star-forming region as follows:
be59 = Cl Berkeley 59
cepa = Cep A
cepb = Cep B
cepc = Cep C
eagle = Eagle Nebula
flame = Flame Nebula
ggd12_15 = GGD 12-15
ic348 = IC 348
ic5146 = IC 5146
lkha101 = LkHa 101 cluster
m17 = M 17
ngc1893 = NGC 1893
ngc6357 = NGC 6357
ngc7160 = MGC 7160
orion = Orion
rcw36 = RCW 36
rosette = Rosette
serpens = Serpens
w40 = W40
Note (2): This unique source's name keyword can be used to retrieve other
numerous X-ray, near-IR, and mid-IR source's properties from the YSO catalogue
data sets of Broos et al. (2013ApJS..209...32B 2013ApJS..209...32B, Cat. J/ApJS/209/32, MYStIX)
and Getman et al. (2017ApJS..229...28G 2017ApJS..229...28G, Cat. J/ApJS/229/28, SFiNCs).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Apr-2021