J/AJ/150/145 YSOVAR infrared photometry in GGD12-15 (Wolk+, 2015)
YSOVAR: mid-infrared variability among YSOs in the star formation region
GGD12-15.
Wolk S.J., Gunther H.M., Poppenhaeger K., Cody A.M., Rebull L.M.,
Forbrich J., Gutermuth R.A., Hillenbrand L.A., Plavchan P., Stauffer J.R.,
Covey K.R., Song I.
<Astron. J., 150, 145 (2015)>
=2015AJ....150..145W 2015AJ....150..145W (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Stars, variable ; Photometry, infrared ; Infrared sources ;
Stars, pre-main sequence ; X-ray sources
Keywords: infrared: stars - stars: evolution - stars: formation -
stars: pre-main sequence - stars: protostars -
stars: variables: T Tauri, Herbig Ae/Be
Abstract:
We present an IR-monitoring survey with the Spitzer Space Telescope of
the star-forming region GGD 12-15. More than 1000 objects were
monitored, including about 350 objects within the central 5', which is
found to be especially dense in cluster members. The monitoring took
place over 38 days and is part of the Young Stellar Object VARiability
project. The region was also the subject of a contemporaneous 67 ks
Chandra observation. The field includes 119 previously identified
pre-main sequence star candidates. X-rays are detected from 164
objects, 90 of which are identified with cluster members. Overall, we
find that about half the objects in the central 5' are young stellar
objects (YSOs) based on a combination of their spectral energy
distribution, IR variability, and X-ray emission. Most of the stars
with IR excess relative to a photosphere show large amplitude (>0.1
mag) mid-infrared (mid-IR) variability. There are 39 periodic sources,
and all but one is found to be a cluster member. Almost half of the
periodic sources do not show IR excesses. Overall, more than 85% of
the Class I, flat spectrum, and Class II sources are found to vary.
The amplitude of the variability is larger in more embedded YSOs. Most
of the Class I/II objects exhibit redder colors in a fainter state,
which is compatible with time-variable extinction. A few become bluer
when fainter, which can be explained with significant changes in the
structure of the inner disk. A search for changes in the IR due to
X-ray events is carried out, but the low number of flares prevented an
analysis of the direct impact of X-ray flares on the IR light curves.
However, we find that X-ray detected Class II sources have longer
timescales for change in the MIR than a similar set of non-X-ray
detected Class IIs.
Description:
We present Spitzer IRAC 3.6 and 4.5µm and Chandra observations for
Young Stellar Objects (YSOs) and YSO candidates in the GGD 12-15
region.
GGD 12-15 was observed with the Chandra X-ray Observatory 2010
December 15 for about 67ks, starting at 14:04 UT (ObsID 12392).
As part of YSOVAR, the field was observed using Spitzer from 2010
November 16 to December 24. The YSOVAR data consist of 77 observations
of GGD 12-15 over a 38-day period with a total exposure time of
14.7hr. There was also a 20hr staring mode observation, which
overlapped the X-ray observation from 14:06 UT 2010 December 15 to
09:39 UT December 16.
Overall, 1017 infrared sources were analyzed (see Table1).
Objects:
-----------------------------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------------------------
06 10 51.0 -06 11 54 GGD 12-15 = [BDB2003] G213.88-11.83
-----------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 320 1017 Source designations, flux densities and light
curve properties
table2.dat 127 90 Properties of X-ray sources
table3.dat 61 39 Properties of periodic sources
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See also:
J/AJ/150/118 : YSOVAR photometry in IRAS 20050+2720 (Poppenhaeger+, 2015)
J/AJ/148/122 : YSOVAR: infrared photometry in Lynds 1688 (Gunther+, 2014)
J/AJ/145/66 : Spitzer light curves of YSOs in IC 348 (Flaherty+, 2013)
J/AJ/144/101 : Multiwavelength data of IRAS 20050+2720 SFR (Guenther+, 2012)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/AJ/135/693 : X-ray and IR sources in RCW 108 (Wolk+, 2008)
J/AJ/132/1100 : X-ray and IR sources in RCW 38 (Wolk+, 2006)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- --- [SSTYSV]
8- 26 A19 --- SSTYSV IAU designation within the Spitzer Space
Telescope (SST) Young Stellar Object
VARiability (YSOVAR) program
(JHHMMSS.ss+DDMMSS.s)
28- 38 F11.8 deg RAdeg Right ascension in decimal degrees (J2000)
40- 51 F12.9 deg DEdeg Declination in decimal degrees (J2000)
53- 54 I2 --- o_<[3.6]> [0/80] Number of datapoints in [3.6] band light
curve
56- 57 I2 --- o_<[4.5]> [0/80] Number of datapoints in [4.5] band light
curve
59- 60 I2 --- Nboth [0/79] Number of datapoints in light curve with
both [3.6] and [4.5] data
62- 67 F6.3 mag <[3.6]> [7.4/16.7]? Mean 3.6µm band light curve
magnitude
69- 74 F6.3 mag <[4.5]> [6.6/16.4]? Mean 4.5µm band light curve
magnitude
76- 81 F6.3 mag med3.6 [7.4/16.7]? Median 3.6µm band light curve
magnitude
83- 88 F6.3 mag med4.5 [6.6/16.4]? Median 4.5µm band light curve
magnitude
90- 94 F5.3 mag MAD3.6 [0/0.19]? Median Absolute Deviation of 3.6µm
band light curve
96-100 F5.3 mag MAD4.5 [0/0.27]? Median absolute deviation of 4.5µm
band light curve
102-106 F5.3 mag s_<[3.6]> [0.01/0.61]? Width of 3.6µm band
distribution from 10% to 90%
108-112 F5.3 mag s_<[4.5]> [0.01/1.4]? Width of 4.5µm band distribution
from 10% to 90%
114-119 F6.2 mag chi3.6 [0.1/326.2]? Reduced χ2 to mean of
3.6µm band
121-126 F6.2 mag chi4.5 [0.05/568.3]? Reduced χ2 to mean of
4.5µm band
128-131 F4.1 d t3.6 [0.2/10.6]? Decay time of AutoCorrelation
Function (ACF) in 3.6µm band
133-136 F4.1 d t4.5 [0.2/10.2]? Decay time of ACF in 4.5µm band
138-149 F12.9 rad CMD [-0.4/16.2]? Angle of best-fit line in [3.6],
[3.6]-[4.5] color-Magnitude Diagram (CMD)
151-154 F4.2 rad e_CMD [0/0.54]? Uncertainty in CMD
156-160 F5.2 mag Length [-1.57/1.57]? Length of best-fit line in [3.6],
[3.6]-[4.5] CMD
162-165 F4.2 --- Stet [0/1.6]? Stetson index for 3.6 and 4.5µm
two-band light curve
167-172 F6.3 mag Jmag [8.7/17.6]? 2MASS J band magnitude
174-179 F6.3 mag Hmag [7.7/16.8]? 2MASS H band magnitude
181-186 F6.3 mag Kmag [7.3/15.9]? 2MASS Ks band magnitude
188-195 F8.5 mag [3.6] [7.2/17.6]? Spitzer/IRAC cryomission 3.6µm
band magnitude (1)
197-204 F8.5 mag [4.5] [6.7/17.1]? Spitzer/IRAC cryomission 4.5µm
band magnitude (1)
206-213 F8.5 mag [5.8] [5.3/16.3]? Spitzer/IRAC cryomission 5.8µm
band magnitude (1)
215-222 F8.5 mag [8.0] [3.4/15.1]? Spitzer/IRAC cryomission 8.0µm
band magnitude (1)
224-232 F9.6 mag [24] [0.3/11]? Spitzer/MIPS cryomission 24µm band
magnitude (1)
234-238 F5.3 mag e_Jmag [0/0.3]? Observational uncertainty in Jmag
240-244 F5.3 mag e_Hmag [0/0.3]? Observational uncertainty in Hmag
246-250 F5.3 mag e_Kmag [0/0.3]? Observational uncertainty in Kmag
252-261 F10.8 mag e_[3.6] [0/0.31]? Observational uncertainty in [3.6] (1)
263-272 F10.8 mag e_[4.5] [0/0.4]? Observational uncertainty in [4.5] (1)
274-283 F10.8 mag e_[5.8] [0/0.9]? Observational uncertainty in [5.8] (1)
285-294 F10.8 mag e_[8.0] [0/1.7]? Observational uncertainty in [8.0] (1)
296-305 F10.8 mag e_[24] [0/1.1]? Observational uncertainty in [24] (1)
307-308 I2 --- Cl1 [0/99]? Infrared class from Gutermuth et al.
2009 (cat. J/ApJS/184/18)
310-312 A3 --- Cl2 Infrared class according to Spectral Energy
Distribution (SED) slope (F, I, II, or III) (G1)
314 I1 --- Var [0/1] Variable source flag (1=yes or 0=no)
316 I1 --- Xr [0/1] Chandra counterpart flag (1=yes or 0=no)
318 I1 --- Std [0/1] Source in YSOVAR standard set of cluster
members (1=yes or 0=no)
320 I1 --- Aug [0/1] In the augmentation to the standard set
of members (1=yes or 0=no)
--------------------------------------------------------------------------------
Note (1): Column taken directly from Gutermuth et al. 2009 (cat. J/ApJS/184/18)
and republished here for completeness.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- --- [SSTYSV]
8- 26 A19 --- SSTYSV IAU designation within the Spitzer Space
Telescope (SST) Young Stellar Object
VARiability (YSOVAR) program
(JHHMMSS.ss+DDMMSS.s)
28- 38 F11.8 deg RAdeg Right ascension in decimal degrees (J2000)
40- 51 F12.9 deg DEdeg Declination in decimal degrees (J2000)
53- 56 I4 ct Rcts [5/1333] Raw X-ray counts
58- 63 F6.1 ct Ncts [4/1329.3] Net X-ray counts
65- 69 F5.2 10+21/cm2 NH [0/15.7]? Fitted Hydrogen column density
71- 74 F4.2 10+21/cm2 e_NH [0.03/4.3]? Error in fitted NH column
76- 80 F5.2 keV kT [0.2/15]? Fitted temperature
82- 87 F6.3 keV e_kT [0/29.1]? Error in kT
89 A1 --- f_kT [n] Indicates kT error is nan
91- 98 E8.2 mW/m2 Flux1 ? Source flux after absorption correction
(in units of erg/s/cm2)
100-107 E8.2 mW/m2 Flux0 ? Source flux without absorption correction
(in units of erg/s/cm2)
109-112 F4.2 --- chi2 [0/1.71]? Reduced χ2 of the spectral
fit
114-118 A5 --- Stat c-statistic or χ-data variance used?
(cstat or dvar)
120-124 F5.3 --- Prob [0/1] Probability that source is an X-ray
variable
126-127 I2 --- Var [0/10] G-L variable index
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- SSTYSV IAU designation within the Spitzer Space
Telescope (SST) Young Stellar Object
VARiability (YSOVAR) program
(JHHMMSS.ss+DDMMSS.s)
21- 23 A3 --- Xr X-ray source? (yes or no)
25- 27 A3 --- Mm Standard set or cluster member? (yes or no)
29- 34 F6.3 d Per [0.14/14] Period
36- 39 F4.1 --- Power [12.4/35.4] Periodogram peak power
41 A1 --- l_FAP [<] Upper limit flag on FAP
42- 46 F5.3 --- FAP [0.001/0.03] False Alarm probability
48- 57 A10 --- Cl1 Infrared class from Gutermuth et al. 2009
(cat. J/ApJS/184/18) (II, III, or Transition)
59- 61 A3 --- Cl2 Infrared class according to Spectral Energy
Distribution (SED) slope (F, I, II, or III) (G1)
--------------------------------------------------------------------------------
Global Notes:
Note (G1): Spectral index code defined as:
F = Source with flat SED;
I = Source with Class I SED (star+disk+envelope);
II = Class II source (star+disk);
III = Source with no excess relative to a photospheric SED (diskless).
History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 18-Apr-2016