J/ApJ/933/77 Temparature & luminosity of Gaia EDR3 Serpens members (Zhou+, 2022)
The ages of optically bright subclusters in the Serpens star-forming region.
Zhou X., Herczeg G.J., Liu Y., Fang M., Kuhn M.
<Astrophys. J., 933, 77 (2022)>
=2022ApJ...933...77Z 2022ApJ...933...77Z
ADC_Keywords: Star Forming Region; Stars, ages; Photometry; Optical; Infrared;
Effective temperatures; Stars, masses
Keywords: Young star clusters; T Tauri stars; Spectral energy distribution
Star forming regions
Abstract:
The Serpens Molecular Cloud is one of the most active star-forming
regions within 500pc, with over 1000 young stellar objects (YSOs) at
different evolutionary stages. The ages of the member stars inform us
about the star formation history of the cloud. In this paper, we
develop a spectral energy distribution (SED) fitting method for nearby
evolved (diskless) young stars from members of the Pleiades to
estimate their ages, with a temperature scale adopted from APOGEE
spectra. When compared with literature temperatures of selected YSOs
in Orion, the SED fits to cool (<5000K) stars have temperatures that
differ by an average of ≤50K and have a scatter of ∼210K for both
disk-hosting and diskless stars. We then apply this method to YSOs in
the Serpens Molecular Cloud to estimate ages of optical members
previously identified from Gaia DR2 astrometry data. The optical
members in Serpens are concentrated in different subgroups with ages
from ∼4 to ∼22Myr; the youngest clusters, W40 and Serpens South, are
dusty regions that lack enough optical members to be included in this
analysis. These ages establish that the Serpens Molecular Cloud has
been forming stars for much longer than has been inferred from
infrared surveys.
Description:
In this paper, we develop a new SED fitting routine designed for young
stars and then apply the fitting routine to optical members of Serpens
to estimate stellar ages by comparing best-fit temperature and
luminosities to model isochrones. The photometry used
in this paper is obtained from the Two Micron All Sky Survey, ALLWISE,
Pan-STARRS1, APASS and Gaia EDR3.
The SED fits are designed to derive the stellar properties of the
∼700 high-confidence members of the Serpens star-forming complex with
Gaia DR2 astrometry (published in Herczeg+ 2019ApJ...878..111H 2019ApJ...878..111H).
Among the ∼700 high-confidence members in Herczeg+ (2019ApJ...878..111H 2019ApJ...878..111H),
∼20 stars have no Gaia BP or RP photometry, ∼20 stars have no 2MASS
data with a cross-match radius of 2", and ∼80 stars do not pass the
2MASS data selection criteria, in most cases because the objects
appear elongated by a companion or visual binary. Thus, over 100 stars
are removed from the sample, leaving 569 stars for analysis.
About half of the optical members of the Serpens cloud are located in
three distinct clusters, Serpens Main, Serpens Northeast, Serpens far
South. A few optical members are located in smaller groups, and the
rest are distributed throughout the complex (Distrib group).
Objects:
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RA (2000) DE Designation(s)
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18 29 48.99 +01 14 48.0 Serpens = NAME SER MCLD
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 100 618 Fits of Serpens members
table6.dat 44 7 Ages of Serpens groups with nonmagnetic
isochrones, estimated with isochrone fitting
table8.dat 48 8 Proper Motion and Radial Velocity of Serpens
groups and Collinder 359
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/336 : AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/A+A/492/277 : VOSA. An application to Collinder 69 open cluster (Bayo, 2008)
J/ApJ/677/401 : X-ray properties of protostars in ONC (Prisinzano, 2008)
J/AJ/144/192 : Spitzer survey of Orion A and B. I. YSO catalog (Megeath, 2012)
J/ApJS/207/5 : YSOs in Lynds 1641: disks, accretion & SFH (Fang+, 2013)
J/ApJS/209/29 : MYStIX: Mid-IR observations and catalogs (Khun+, 2013)
J/AJ/153/188 : Spectroscopy of the foreground pop in Orion A (Fang+, 2017)
J/ApJS/229/28 : SFiNCs: X-ray & IR source cat. and membership (Getman+, 2017)
J/ApJ/878/111 : Members in Serpens MoCl with Gaia DR2 (Herczeg+, 2019)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- --- [Gaia EDR3]
11- 29 I19 --- GaiaEDR3 Gaia EDR3 identifier
31- 39 F9.5 deg RAdeg Gaia EDR3 right Ascension (ICRS) at Ep=2016.0
41- 48 F8.5 deg DEdeg Gaia EDR3 Declination (ICRS) at Ep=2016.0
50- 62 A13 --- Reg Region
64- 69 F6.2 pc Dist [336/639] Distance from Gaia EDR3 parallax
71- 74 I4 K Teff [3005/9689]? Surface effective temperature
76- 79 F4.2 mag Av [0/6]? V-band extinction
81- 85 F5.2 [Lsun] logL [-1.75/2.16]? log of luminosity
87- 91 F5.2 Myr Age [1/47.8]? Age
93- 96 F4.2 Msun Mstar [0.09/3.5]? Stellar mass
98 I1 --- Disk ? Flag on disk (1)
100 I1 --- Flag Flag (=1) if used in calculating cluster ages
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Note (1) : Flag as follows (see Sec.4.1):
0 = diskless
1 = if disk
null = no disk information
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Reg Region identifier as in Table 5
15- 17 F3.1 Myr AgeD [2.9/9.5]? Age of disk
19- 21 F3.1 Myr e_AgeD [0.5/9.3]? Error on AgeD
23- 26 F4.1 Myr AgeDl [4/22]? Age of diskless
28- 30 F3.1 Myr e_AgeDl [0.2/1.6]? Error on AgeDl
32- 35 F4.1 Myr AgeTot [4/22]? Age of total (1)
37- 39 F3.1 Myr e_AgeTot [0.2/1.4]? Error on AgeTot
41- 44 F4.2 --- fdisk [0/0.22]? Disk fraction
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Note (1): Total includes disk and diskless, and sources with no disk
information.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Reg Region identifier as in Table 5 (+Collinder 359)
15- 18 F4.2 mas/yr pmRA [0.64/3.1]? Proper motion in right ascension
20- 23 F4.2 mas/yr e_pmRA [0.16/0.6]? Standard error (σ) on pmRA
25- 30 F6.2 mas/yr pmDE [-10.3/-8.1]? Proper motion in declination
32- 35 F4.2 mas/yr e_pmDE [0.06/0.7]? Standard error (σ) on pmDE
37- 41 F5.1 km/s RV [-12.1/11]? Radial velocity
43- 45 F3.1 km/s e_RV [2.1/5.5]? Sigma uncertainty in RV
47- 48 I2 --- Ns [2/11]? Number of stars to calculate RV
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History:
From electronic version of the journal
(End) Prepared by [AAS], Katia van-der-Woerd [CDS] 19-Apr-2024