J/MNRAS/477/5191 Galactic young stellar cluster lifetimes (Richert+, 2018)
Circumstellar disc lifetimes in numerous galactic young stellar clusters.
Richert A.J.W., Getman K.V., Feigelson E.D., Kuhn M.A., Broos P.S.,
Povich M.S., Bate M.R., Garmire G.P.
<Mon. Not. R. Astron. Soc., 477, 5191-5206 (2018)>
=2018MNRAS.477.5191R 2018MNRAS.477.5191R (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:
Photometric detections of dust circumstellar discs around pre-main
sequence (PMS) stars, coupled with estimates of stellar ages, provide
constraints on the time available for planet formation. Most previous
studies on disc longevity, starting with Haisch, Lada & Lada, use star
samples from PMS clusters but do not consider data sets with
homogeneous photometric sensitivities and/or ages placed on a uniform
time-scale. Here we conduct the largest study to date of the longevity
of inner dust discs using X-ray and 1-8um infrared photometry from the
MYStIX and SFiNCs projects for 69 young clusters in 32 nearby
star-forming regions with ages t≤5Myr. Cluster ages are derived by
combining the empirical AgeJX method with PMS evolutionary models,
which treat dynamo-generated magnetic fields in different ways.
Leveraging X-ray data to identify disc-free objects, we impose similar
stellar mass sensitivity limits for disc-bearing and disc-free young
stellar objects while extending the analysis to stellar masses as low
as M∼0.1M☉. We find that the disc longevity estimates are
strongly affected by the choice of PMS evolutionary model. Assuming a
disc fraction of 100 per cent at zero age, the inferred disc half-life
changes significantly, from t1/2∼1.3-2Myr to t1/2∼3.5Myr when
switching from non-magnetic to magnetic PMS models. In addition, we
find no statistically significant evidence that disc fraction varies
with stellar mass within the first few Myr of life for stars with
masses <2M☉, but our samples may not be complete for more
massive stars. The effects of initial disc fraction and star-forming
environment are also explored.
Description:
In this work, we have studied circumstellar disc longevity in 69 young
stellar clusters by combining X-ray and infrared data and studying
cluster disc fraction as a function of age. We have applied
homogeneously derived cluster ages (based on the AgeJX method) and
carefully accounted for the relative sensitivity to different clusters
in the infrared and X-ray bands. The SFiNCs and MYStIX samples
collectively exceed previous cluster samples by more than a factor of
three.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 276 Properties of MYStIX and SFiNCs clusters
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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- 6 A6 --- Sample Sample (MYStIX or SFiNCs)
8- 25 A18 --- Cluster Region/Cluster
27- 29 F3.1 Myr AgeJXS Cluster age using Siess00
PMS evolutionary model (1)
31- 33 F3.1 Myr e_AgeJXS rms uncertainty on AgeJXS
35- 37 F3.1 Myr AgeJXM Cluster age using MIST
PMS evolutionary model (1)
39- 41 F3.1 Myr e_AgeJXM rms uncertainty on AgeJX
43- 45 F3.1 Myr AgeF Cluster age using Feiden16M
PMS evolutionary model (1)
47- 55 A9 --- Class YSO classes (2)
57 A1 --- Incl [Y/N] Include possible protostars? (2)
59- 62 F4.2 Msun Mcut Minimum mass cut-off
(based on the Siess00 age scale)
63 A1 --- u_Mcut Uncertainty flag on Mcut
65- 68 F4.2 Msun MassMed Median stellar mass in a cluster
(based on the Siess00 age scale)
70- 72 I3 --- Ndisc Numbers of disk-bearing YSOs after the
imposition of Mcut
74- 76 I3 --- Nnodisc Numbers of disk-free YSOs after the
imposition of Mcut
78- 81 F4.2 --- fdisk Inferred disk fraction,
fdisk=Ndisk/(Ndisk+Nnodisk)
83- 86 F4.2 --- E_fdisk Error on fdisk (upper value)
88- 91 F4.2 --- e_fdisk Error on fdisk (lower value)
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Note (1): PMS evolutionary models used:
Siess00 = Siess et al., 2000A&A...358..593S 2000A&A...358..593S
MIST = Choi et al., 2016ApJ...823..102C 2016ApJ...823..102C
Feinden16 = Feiden, 2016A&A...593A..99F 2016A&A...593A..99F
Note (2): This is the long version of Table 1 that shows 69x4 entries; that is,
each cluster has four entries, one for each of the four membership
permutations yielded by using two different YSO classification schemes
(YSO Classes = Catalog and YSO Classes = alphaIRAC) and including and
excluding probable protostars (Y/N).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 16-Jun-2021