J/AJ/148/122 YSOVAR: infrared photometry in Lynds 1688 (Gunther+, 2014)
YSOVAR: mid-infrared variability in the star-forming region Lynds 1688.
Gunther H.M., Cody A.M., Covey K.R., Hillenbrand L.A., Plavchan P.,
Poppenhaeger K., Rebull L.M., Stauffer J.R., Wolk S.J., Allen L., Bayo A.,
Gutermuth R.A., Hora J.L., Meng H.Y.A., Morales-Calderon M., Parks J.R.,
Song I.
<Astron. J., 148, 122 (2014)>
=2014AJ....148..122G 2014AJ....148..122G
ADC_Keywords: Molecular clouds ; YSOs ; Stars, variable ; Photometry, infrared
Keywords: accretion, accretion disks - stars: formation -
stars: pre-main sequence - stars: protostars -
stars: variables: T Tauri, Herbig Ae/Be
Abstract:
The emission from young stellar objects (YSOs) in the mid-infrared
(mid-IR) is dominated by the inner rim of their circumstellar disks.
We present IR data from the Young Stellar Object VARiability (YSOVAR)
survey of ∼800 objects in the direction of the Lynds 1688 (L1688)
star-forming region over four visibility windows spanning 1.6yr using
the Spitzer Space Telescope in its warm mission phase. Among all light
curves, 57 sources are cluster members identified based on their
spectral energy distribution and X-ray emission. Almost all cluster
members show significant variability. The amplitude of the variability
is larger in more embedded YSOs. Ten out of 57 cluster members have
periodic variations in the light curves with periods typically between
three and seven days, but even for those sources, significant
variability in addition to the periodic signal can be seen. No period
is stable over 1.6yr. Nonperiodic light curves often still show a
preferred timescale of variability that is longer for more embedded
sources. About half of all sources exhibit redder colors in a fainter
state. This is compatible with time-variable absorption toward the
YSO. The other half becomes bluer when fainter. These colors can only
be explained with significant changes in the structure of the inner
disk. No relation between mid-IR variability and stellar effective
temperature or X-ray spectrum is found.
Description:
We present a Spitzer/IRAC monitoring campaign of the star-forming
region L1688 in the mid-infrared. Lynds 1688 (L1688) is a subcloud of
the ρ Ophiuchus star-forming region.
Three fields in L1688 were observed with Spitzer in four observing
windows from 2010 April 12 to 2010 May 16 (visibility window 1), 2010
September 22 to 2010 October 27 (visibility window 2), 2011 April 20
to 2011 May 23 (visibility window 3), and 2011 October 1 to 2011
November 6 (visibility window 4). These windows are consecutive
visibility periods dictated by the Spitzer orbit (Werner et al.,
2004ApJS..154....1W 2004ApJS..154....1W).
Table1 lists the time of each observation. They can be found under
Program Identification number (PID) 61024 in the Spitzer Heritage
Archive (http://sha.ipac.caltech.edu/applications/Spitzer/SHA).
L1688 was observed by Chandra on 2000 April 13 for 100ks exposure time
in the FAINT mode with the ACIS instrument (ObsID 635 in the Chandra
Data Archive, http://cda.harvard.edu/chaser/).
We found auxiliary data from the literature. L1688 was observed with
Spitzer in the cryogenic mission phase with all four IRAC channels and
the 24µm channel of the Multiband Imaging Photometer for Spitzer
(MIPS). We augment our own Spitzer data reduction with values from the
catalog published by the c2d project (c2d = "From Cores to Disks";
Evans et al. 2003, cat. II/332). Near-infrared data are taken from
2MASS (cat. II/246). Additionally, we take detections from the UKIRT
Infrared Deep Sky Survey (UKIDSS; cat. II/319) Galactic cluster
survey, data release 9. UKIDSS uses the United Kingdom Infrared
Telescope (UKIRT) Wide Field Camera. The YSOVAR data is also
cross-matched with data from the SIMBAD
(http://simbad.u-strasbg.fr/simbad/) service to provide an
identification with known objects from the literature.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 48 108 Observation log
table2.dat 586 882 Source designations, flux densities, and light
curve properties
table4.dat 52 14 Periodic sources in the fast-cadence data
table5.dat 49 17 New members for L1688 in addition to the YSOVAR
standard member set and Wilking et al. 2008
(cat. II/289)
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See also:
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/289 : JKH photometry in LDN 1688 (Wilking+, 2008)
II/332 : c2d Spitzer final data release (DR4) (Evans+, 2003)
J/ApJS/211/3 : NIR photometry variability in ρ Oph (Parks+, 2014)
J/ApJ/753/149 : YSOVAR: 6 eclipsing binaries in Orion (Morales-Calderon+, 2012)
J/AJ/142/140 : Optical spectroscopy of ρ Oph stars. II. (Erickson+, 2011)
J/ApJ/733/50 : Mid-IR photometry in the ONC (Morales-Calderon+, 2011)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/ApJ/566/993 : Lynds 1688 cluster NICMOS imaging (Allen+, 2002)
http://sha.ipac.caltech.edu/applications/Spitzer/SHA : Spitzer Heritage Archive
http://cda.harvard.edu/chaser/ : Chandra Data Archive
http://github.com/YSOVAR : YSOVAR custom routines in Python
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- AOR Spitzer Astronomical Observation Request (AOR)
identification number (1)
10- 19 A10 "Y:M:D" Obs0.date Starting UT date of the observation
21- 28 A8 "h:m:s" Obs0.time Starting UT time of the observation
30- 39 A10 "Y:M:D" Obs1.date Ending UT date of the observation
41- 48 A8 "h:m:s" Obs1.time Ending UT time of the observation
--------------------------------------------------------------------------------
Note (1): Under Program Identification number (PID) 61024 in the Spitzer
Heritage Archive (http://sha.ipac.caltech.edu/applications/Spitzer/SHA).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
11- 19 F9.5 deg DEdeg Declination in decimal degrees (J2000)
21- 46 A26 --- Name Object name (1)
48- 53 A6 --- --- [SSTYSV]
55- 73 A19 --- SSTYSV IAU designation in the Spitzer Space Telescope
YSOVAR survey (JHHMMSS.ss+DDMMSS.s) (2)
75-143 A69 --- OName Other object identifier(s)
145-150 A6 --- --- [SSTc2d]
152-167 A16 --- SSTc2d Identifier in the Spitzer Space Telescope c2d
project (JHHMMSS.S+DDMMSS) (3)
169-174 I6 --- W+08 [40/258]?=-99999 Identifier in Wilking et al. 2008
(cat. II/289)
176-194 A19 --- AOC08 Identifier in Alves de Oliveira & Casali 2008
(cat. J/A+A/485/155) (JHHMMSS.ss+HHMMSS.s)
196-207 I12 --- UKIDSS ?=-99999 UKIDSS object identifier (4)
209-213 F5.2 mag Jmag [9.4/17.6]? The 2MASS J band magnitude
215-218 F4.2 mag e_Jmag ? Uncertainty in Jmag
220-224 A5 --- r_Jmag Data reference source for Jmag (5)
226-230 F5.2 mag Hmag [8.6/16.9]? The 2MASS H band magnitude
232-235 F4.2 mag e_Hmag ? Uncertainty in Hmag
237-241 A5 --- r_Hmag Data reference source for Hmag (5)
243-247 F5.2 mag Kmag [7.8/15.5]? The 2MASS Ks band magnitude
249-252 F4.2 mag e_Kmag ? Uncertainty in Kmag
254-258 A5 --- r_Kmag Data reference source for Kmag (5)
260-264 F5.2 mag [3.6] [6.4/17.9]? Spitzer/IRAC 3.6µm band magnitude
266-269 F4.2 mag e_[3.6] ? Uncertainty in [3.6]
271-273 A3 --- r_[3.6] Data reference source for [3.6] (5)
275-279 F5.2 mag [4.5] [5/17.4]? Spitzer/IRAC 4.5µm band magnitude
281-284 F4.2 mag e_[4.5] ? Uncertainty in 4.5mag
286-288 A3 --- r_[4.5] Data reference source for [4.5] (5)
290-294 F5.2 mag [5.8] [3.8/15.6]? Spitzer/IRAC 5.8µm band magnitude
296-299 F4.2 mag e_[5.8] ? Uncertainty in [5.8]
301-303 A3 --- r_[5.8] Data reference source for [5.8] (5)
305-309 F5.2 mag [8.0] [2.6/14.9]? Spitzer/IRAC 8µm band magnitude
311-314 F4.2 mag e_[8.0] ? Uncertainty in [8.0]
316-318 A3 --- r_[8.0] Data reference source for [8.0] (5)
320-324 F5.2 mag [24] [0.5/10.3]? Spitzer/MIPS 24um band magnitude (6)
326-329 F4.2 mag e_[24] ? Uncertainty in [24]
331-333 A3 --- r_[24] Data reference source for [24] (5)
335-337 A3 --- Cl1 Infrared (IR) class according to Spectral Energy
Distribution (SED) slope in all visibility
windows (F, I, II, or III) (G1)
339-341 A3 --- Cl2 IR class according to SED slope in visibility
window 1 only (F, I, II, or III) (G1)
343-347 A5 --- Mm Cluster membership according to YSOVAR standard
(False or True)
349-353 A5 --- Std Source in YSOVAR standard set? (False or True) (7)
355-356 I2 ct N36 Number of data points in the 3.6µm band
(for first visibility window only) (1)
358-359 I2 ct N45 Number of data points in the 4.5µm band
(for first visibility window only) (1)
361-365 F5.2 mag M36 ? Maximum of 3.6µm band magnitude in light
curve (for first visibility window) (1)
367-371 F5.2 mag m36 ? Minimum of 3.6µm band magnitude in light
curve (for first visibility window only) (1)
373-377 F5.2 mag M45 ? Maximum of 4.5µm band magnitude in light
curve (for first visibility window only) (1)
379-383 F5.2 mag m45 ? Minimum of 4.5µm band magnitude in light
curve (for first visibility window only) (1)
385-389 F5.2 mag <[36]> ? Mean Spitzer/IRAC 3.6µm band magnitude (for
first visibility window only) (1)
391-394 F4.2 mag e_<[36]> ? Standard deviation in <[36]> (8)
396-399 F4.2 mag W36 ? Width of Spitzer/IRAC 3.6µm band (for first
visibility window only) (9)
401-405 F5.2 mag <[45]> ? Mean Spitzer/IRAC 4.5µm band magnitude (for
first visibility window only) (1)
407-410 F4.2 mag e_<[45]> ? Standard deviation in <[45]> (8)
412-415 F4.2 mag W45 ? Width of Spitzer/IRAC 4.5µm band (for first
visibility window only) (9)
417-422 F6.2 --- chi36 ? Reduced χ2 to mean 3.6µm band
(for first visibility window only) (1)
424-429 F6.2 --- chi45 ? Reduced χ2 to mean 4.5µm band
(for first visibility window only) (1)
431-433 F3.1 d t36 ? Decay time of 3.6µm band AutoCorrelation
Function (ACF) (for first visibility window
only) (1)
435-437 F3.1 d t45 ? Decay time of 4.5µm band ACF (for first
visibility window only) (1)
439-443 F5.2 --- Stet1 ? Stetson index for 3.6 and 4.5µm band light
curves (for first visibility window only) (1)
445-449 F5.2 rad CMD1 ? Angle of best-fit line in Color-Magnitude
Diagram (CMD) for 3.6 and 4.5µm bands (in
first visibility window only) (1)
451-454 F4.2 rad e_CMD1 ? Uncertainty in CMD1
456-458 I3 ct N3.6 Number of data points in entire 3.6µm band
light curve (1)
460-462 I3 ct N4.5 Number of data points in entire 4.5µm band
light curve (1)
464-468 F5.2 mag M3.6 ? Maximum magnitude in entire 3.6µm band light
curve (1)
470-476 F7.4 mag m3.6 ? Minimum magnitude in entire 3.6µm band light
curve (1)
478-482 F5.2 mag M4.5 ? Maximum magnitude in entire 4.5µm band light
curve (1)
484-490 F7.4 mag m4.5 ? Minimum magnitude in entire 4.5µm band light
curve (1)
492-496 F5.2 mag <[3.6]> ? Mean magnitude in entire Spitzer/IRAC 3.6µm
band light curve (1)
498-508 F11.9 mag e_<[3.6]> ? Standard deviation in <[3.6]> (8)
510-513 F4.2 mag W3.6 ? Width of entire Spitzer/IRAC 3.6µm band light
curve (9)
515-519 F5.2 mag <[4.5]> ? Mean magnitude in entire Spitzer/IRAC 4.5µm
band light curve (1)
521-531 F11.9 mag e_<[4.5]> ? Standard deviation in <[4.5]> (8)
533-536 F4.2 mag W4.5 ? Width of entire Spitzer/IRAC 4.5µm band light
curve (9)
538-544 F7.2 --- chi3.6 ? Reduced χ2 to mean of entire 3.6µm band
light curve (1)
546-552 F7.2 --- chi4.5 ? Reduced χ2 to mean of entire 4.5µm band
light curve (1)
554-558 F5.2 --- Stet ? Stetson index for entire 3.6 and 4.5µm band
light curves (1)
560-564 F5.2 rad CMD ? Angle of best-fit line in CMD for entire 3.6 and
4.5µm band light curves (1)
566-569 F4.2 rad e_CMD ? Uncertainty in CMD
571-574 I4 K Teff [0/5040]?=0 Effective temperature from literature
576-580 A5 --- r_Teff Reference for Teff (5)
582-586 A5 --- Xr Chandra counterpart? (False or True)
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Note (1): Three fields in Lynds 1688 were observed with Spitzer in four
observing windows from 2010 April 12 to 2010 May 16 (visibility window 1),
2010 September 22 to 2010 October 27 (visibility window 2), 2011 April 20
to 2011 May 23 (visibility window 3), and 2011 October 1 to 2011 November
6 (visibility window 4).
Note (2): YSOVAR = Young Stellar Object VARiability survey.
Note (3): c2d = "From Cores to Disks" (Evans et al. 2003, cat. II/332).
Note (4): UKIDSS = United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky
Survey (Lawrence et al. 2012, cat. II/319).
Note (5): Reference codes defined as follows:
2MASS = Two Micron All Sky Survey (cat. II/246);
G09 = Gutermuth et al. 2009 (cat. J/ApJS/184/18);
c2d = Evans et al. 2003 (cat. II/332);
Bar12 = Not defined in the paper;
EW11 = Erickson et al. 2011 (J/AJ/142/140)
Note (6): MIPS=Multiband Imaging Photometer for Spitzer.
Note (7): Source with more than five data points in the fast-cadence data
(first visibility window).
Note (8): Calculated from non-biased variance.
Note (9): Of distribution from 10% to 90%.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 26 A26 --- Name Object name
28- 38 A11 --- Channel IRAC channel: [3.6], [4.5], or [3.6]-[4.5] (1)
40- 43 F4.1 d Per [2.2/14.5] Period
45- 48 F4.2 --- Prob [0/1] False-alarm probability
50- 52 A3 --- Cl Observed SED class using the light curves
from visibility window 1 (G1)
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Note (1): Periodicity might be present in more channels. In this table, the
channel adopted as most reliable is given. See Section 4.3 for details.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
11- 19 F9.5 deg DEdeg Declination in decimal degrees (J2000)
21- 46 A26 --- Name Object name
48- 49 A2 --- Cl SED class (G1)
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Global notes:
Note (G1): Spectral index code as follows:
I = Class I source with a spectral slope α>0.3 (with
α=dlog(λFλ)/dlogλ, where λ is the
wavelength and Fλ the flux density per unit wavelength
interval at that wavelength);
F = Flat-spectrum source with -0.3<α<0.3;
II = Class II source with -1.6<α< -0.3;
III = Class III candidate with α< -1.6.
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History:
From electronic version of the journal
References:
Rebull et al., Paper I, 2014AJ....148...92R 2014AJ....148...92R
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 12-Dec-2014