J/ApJ/920/132 NEOWISE 6.5yr variability in YSOs (Park+, 2021)
Quantifying variability of young stellar objects in the mid-infrared over 6years
with the Near-Earth Object Wide-field Infrared Survey Explorer.
Park W., Lee J.-E., Contreras Pena C., Johnstone D., Herczeg G., Lee S.,
Lee S., Bhardwaj A., Moriarty-Schieven G.H.
<Astrophys. J., 920, 132 (2021)>
=2021ApJ...920..132P 2021ApJ...920..132P
ADC_Keywords: YSOs; Photometry, infrared; Star Forming Region
Keywords: Young stellar objects
Abstract:
Variability in young stellar objects (YSOs) can be caused by various
time-dependent phenomena associated with star formation, including
accretion rates, geometric changes in the circumstellar disks,
stochastic hydromagnetic interactions between stellar surfaces and
inner-disk edges, reconnections within the stellar magnetosphere, and
hot/cold spots on stellar surfaces. We uncover and characterize
∼1700 variables from a sample of ∼5400 YSOs in nearby low-mass
star-forming regions using mid-IR light curves obtained from the 6.5yr
Near-Earth Object Wide-field Infrared Survey Explorer All Sky Survey.
The mid-IR variability traces a wide range of dynamical, physical, and
geometrical phenomenon. We classify six types of YSO mid-IR
variability based on their light curves: secular variability (linear,
curved, and periodic) and stochastic variability (burst, drop, and
irregular). YSOs in earlier evolutionary stages have higher fractions
of variables and higher amplitudes for the variability, with the
recurrence timescale of FUor-type outbursts (defined here as ΔW1
or ΔW2>1mag followed by inspection of candidates) of ∼1000yr in
the early embedded protostellar phase. Known eruptive young stars and
subluminous objects show fractions of variables similar to the
fraction (∼55%) found in typical protostars, suggesting that these two
distinct types are not distinct in variability over the 6.5yr
timescale. Along with brightness variability, we also find a diverse
range of secular color variations, which can be attributed to a
competitive interplay between the variable accretion luminosity of the
central source and the variable extinction by material associated with
the accretion process.
Description:
WISE surveyed the entire sky in four bands, W1 (3.4um), W2 (4.6um), W3
(12um), and W4 (22um), with the spatial resolutions of 6.1", 6.4",
6.5", and 12", respectively, from 2010 January to September.
After the depletion of hydrogen from the cryostat, WISE operated using
only the short wavelength bands, W1 and W2. The survey continued as
the NEOWISE Post-Cryogenic Mission for an additional 4 months, until
WISE went into hibernation in 2011 February.
In 2013 September, WISE was reactivated and has performed observations
in W1 and W2 as the NEOWISE-reactivation mission (NEOWISE-R) with the
primary purpose of exploring the Near-Earth Objects (NEOs). NEOWISE-R
is still operating and the latest released data set consists of 6.5yr
W1 and W2 photometric observations.
To ensure a comprehensive list of nearby protostellar sources, our
WISE samples are collected from 20 star-forming regions on the Gould
Belt based on various YSO catalogs. We initially identified
6927 potential YSOs from the NEOWISE archival data.
See Section 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 30 149900 Multi-epoch NEOWISE photometry
table7.dat 122 5398 Statistics of NEOWISE light curves
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See also:
B/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/359 : The VISTA Hemisphere Survey (VHS) catalog DR4.1 (McMahon+, 2013)
II/362 : i-band variability of YSOs (Sergison+, 2020)
J/AJ/121/3160 : JHK photometry near the Trapezium region (Carpenter+, 2001)
J/A+A/458/789 : ISOCAM survey of Serpens/G3-G6 (Djupvik+, 2006)
J/A+A/447/609 : 1.2mm continuum obs. in rho Oph cloud (Stanke+, 2006)
J/A+A/463/1017 : B and V light curves of AA Tau (Bouvier+, 2007)
J/ApJS/179/249 : Low-luminosity embedded protostar population (Dunham+, 2008)
J/ApJ/676/1109 : Velocities of stars in the ONC (Furesz+, 2008)
J/A+A/479/827 : UBVR LCs of weak-line T Tauri stars (Grankin+, 2008)
J/AJ/136/2413 : Galactic midplane Spitzer red sources (Robitaille+, 2008)
J/MNRAS/386/313 : IR observations of Mira variables (Whitelock+, 2008)
J/ApJ/692/973 : Protostars in Perseus, Serpens and Ophiuchus (Enoch+, 2009)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJS/185/198 : The Cepheus flare observed with IRAC and MIPS (Kirk+, 2009)
J/AJ/140/1214 : NIR spectroscopic survey of class I YSOs (Connelley+, 2010)
J/ApJ/743/156 : NEOWISE obs. of NEOs: preliminary results (Mainzer+, 2011)
J/ApJ/733/50 : MIR phot. monitoring of the ONC (Morales-Calderon+, 2011)
J/ApJ/745/19 : Binary systems in Taurus-Auriga (Kraus+, 2012)
J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSOs (Megeath+, 2012)
J/A+A/557/A77 : VR light curves of AA Tau in 2007-2013 (Bouvier+, 2013)
J/ApJ/778/116 : V1647 Ori long-term optical & NIR obs. (Ninan+, 2013)
J/AJ/147/82 : Monitoring of disk-bearing stars in NGC 2264 (Cody+, 2014)
J/AJ/148/122 : YSOVAR: infrared photometry in Lynds 1688 (Gunther+, 2014)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)
J/AJ/150/175 : YSOVAR: infrared photometry in NGC 1333 (Rebull+, 2015)
J/AJ/150/32 : KELT 2006-2013 phot. of V409 Tau & AA Tau (Rodriguez+, 2015)
J/A+A/581/A66 : UV variability and accretion in NGC 2264 (Venuti+, 2015)
J/ApJ/818/59 : IN-SYNC. IV. YSOs in Orion A (Da Rio+, 2016)
J/MNRAS/462/1444 : MHO catalogue for Cassiopeia and Auriga (Froebrich+, 2016)
J/ApJS/224/5 : Herschel Orion Protostar Survey (HOPS): SEDs (Furlan+, 2016)
J/ApJS/225/26 : Very Low-Luminosity Objects from 1.25-850um (Kim+, 2016)
J/MNRAS/465/3039 : Eruptive variable protostars from VVV EW (Contreras+, 2017)
J/MNRAS/465/3011 : VVV high amplitude NIR var. stars (Contreras Pena+, 2017)
J/A+A/607/A127 : 2014-2017 phot. for ASASSN-13db (Sicilia-Aguilar+, 2017)
J/ApJ/854/170 : Methanol (CH3OH) & OH masers in NGC 6334I (Hunter+, 2018)
J/ApJS/234/8 : YSO jets from UWISH2. IV. Cygnus-X outflows (Makin+, 2018)
J/AJ/155/99 : IR var. among YSOs in Serpens South cluster (Wolk+, 2018)
J/MNRAS/486/4590 : 139 high-amplitude variable stars (Contreras+, 2019)
J/AJ/158/54 : Taurus members from stellar to pl. masses (Esplin+, 2019)
J/ApJ/878/111 : Members in Serpens with Gaia DR2 (Herczeg+, 2019)
J/ApJ/877/110 : SPIRITS cat. of IR long period var. (Karambelkar+, 2019)
J/ApJ/883/6 : AllWISE & NEOWISE LCs of Red MSX YSOs (Uchiyama+, 2019)
J/MNRAS/488/1282 : Variable dust emission by WC type WR* (Williams, 2019)
J/ApJ/889/148 : V346 Nor IJHKs photometry & IR spectra (Kospal+, 2020)
J/ApJS/252/32 : MIR outbursts in nearby SDSS galaxies. I. (Jiang+, 2021)
Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- ID Index (G1)
7- 15 F9.3 d MJD [56640.16/59181.4] Modified Julian Date
17- 21 F5.2 mag mag [3.64/16.9] Apparent magnitude in Band
23- 27 F5.3 mag e_mag [0.012/1.3] Uncertainty in mag
29- 30 A2 --- Band NEOWISE band
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- ID Index (G1)
7- 15 F9.5 deg RAdeg [51.3/340.3] Right Ascension (J2000)
17- 25 F9.5 deg DEdeg [-80.4/77.7] Declination (J2000)
27- 28 I2 --- NW1 [3/15] Number of observed epochs in NEOWISE
W1 band
30- 31 I2 --- NW2 [6/15] Number of observed epochs in NEOWISE
W2 band
33- 37 A5 --- Class Evolutionary Stage of YSO (1)
39- 43 F5.2 --- SD/sig [0.08/50.7] SD/sigma
45- 48 F4.2 mag DeltaW2 [0.01/4.4] Delta W2 (Max-Min) in magnitude
50- 58 E9.4 --- LSP [1.5e-9/1] FAP by Lomb-Scargle Periodogram
60- 68 E9.4 --- Lin [2.3e-11/1] FAP by Linear Least-Square Fitting
70- 77 A8 --- secVar Secular variability
("Linear", "Curved" or "Periodic")
79- 87 A9 --- stochVar Stochastic variability
("Burst", "Drop" or "Irregular") (2)
89- 94 F6.3 yr-1 SlopeW2 [-0.48/0.15]? W2 flux slope (3)
96- 99 I4 d Per [200/4800]? Period by Lomb-Scargle
Periodogram (4)
101- 105 F5.3 --- fAmp [0.019/1.2]? Fractional amplitude by
Lomb-Scargle Periodogram (5)
107- 122 A16 --- Cloud Cloud identification ("Aquila", "Auriga/CMC",
"Cepheus", "Chamaeleon", "Corona Australis",
"IC5146", "Lupus", "Musca", "Ophiuchus",
"Orion", "Perseus", "Serpens" & "Taurus")
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Note (1): Class as follows:
P = Protostar;
D = Disk;
PMS+E = Pre-Main Sequence+Evolved (See text).
Note (2): For secular variables, the stochasticity is determined after removal
of secular trends.
Note (3): Annual W2 flux change relative to the median value if a source is
Linear.
Note (4): Period by LSP if a source is Periodic or Curved.
Note (5): Fractional amplitude if a source is Periodic or Curved.
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Global notes:
Note (G1): M, D, and EL are used for the YSOs listed in
Megeath+ (2012, J/AJ/144/192 ; <[MGM2012] NNNN> in Simbad),
Dunham+ (2015, J/ApJS/220/11 ; <SSTgbs JHHMMSSs+DDMMSS> or
<SSTc2d JHHMMSS.s+DDMMSS> in Simbad), and
Esplin & Luhman (2019, J/AJ/158/54), respectively. For M and D,
source numbers are the same as those in their original catalogs.
For EL, the source number is the same as the source order listed in
Table 1 of Esplin & Luhman (2019).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 09-Mar-2023