J/A+A/640/A128 Cygnus OB2 association NIR light curves (Roquette+, 2020)
Near-infrared time-series photometry in the field of Cygnus OB2 association.
II. Mapping the variability of candidate members.
Roquette J., Alencar S.H.P., Bouvier J., Guarcello M.G., Reipurth B.
<Astron. Astrophys. 640, A128 (2020)>
=2020A&A...640A.128R 2020A&A...640A.128R (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Stars, variable ; Stars, pre-main sequence ;
Stars, late-type; Photometry, infrared ; Photometry, CCD
Keywords: infrared: stars - stars: variables: T Tauri, Herbig Ae/Be -
binaries: eclipsing - stars: low-mass - stars: pre-main sequence -
stars: formation
Abstract:
We present the results of a J, H, and K photometric variability survey
of the central 0.78 square degrees of the young OB association Cygnus
OB2. We used data observed with the Wide-Field CAMera at the United
Kingdom Infrared Telescope in 2007 (spanning 217 days) to investigate
the light curves of 5083 low mass candidate members in the association
and explore the occurrence and main characteristics of their
near-infrared variability. We identified 2529 stars (∼50% of the
sample) with significant variability with time-scales ranging from
days to months. We classified the variable stars into the following
three groups according to their light curve morphology: periodic
variability (1697 stars), occultation variability (124 stars), and
other types of variability (726 stars). We verified that the
disk-bearing stars in our sample are significantly more variable in
the near-infrared than diskless stars, with a steep increase in the
disk-fraction among stars with higher variability amplitude. We
investigated the trajectories described by variable stars in the
color-space and measured slopes for 335 stars describing linear
trajectories. Based on the trajectories in the color-space, we
inferred that the sample analyzed is composed of a mix of young stars
presenting variability due to hot and cold spots, extinction by
circumstellar material, and changes in the disk emission in the
near-infrared. We contemplated using the use of near- infrared
variability to identify disk-bearing stars and verified that 53.4% of
the known disk-bearing stars in our sample could have been identified
as such based solely on their variability. We present 18 newly
identified disk- bearing stars and 14 eclipsing binary candidates
among CygOB2 lower-mass members.
Description:
Parameters related to the variability characterization of pre-main
sequence low-mass stars in the Cygnus OB2 Association (RA∼308.25°,
DE∼41.2°). Variability characterization was based on the analysis
of near-infrared JHK light-curves obtained with the WFCAM at the UKIRT
telescope over 112 observed nights in 2007. Data include the
light-curves of the 5083 stars analyzed.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1-5.dat 226 5083 Paper's tables 1 to 5
lc/* . 5083 Individual light curves
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See also:
J/ApJ/773/135 : Disk-bearing stars in Cygnus OB2 (Guarcello+, 2013)
J/A+A/603/A106 : Rotational periods in Cygnus OB2 (Roquette+, 2017)
Byte-by-byte Description of file: table1-5.dat
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Bytes Format Units Label Explanations
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1- 6 I06 --- ID [1/155618] Internal identifier
8- 11 I4 --- GDW15 [119/5699]? Internal identifier in
Guarcello et al., 2015 (2015arXiv150103761G 2015arXiv150103761G)
13- 18 I6 --- GDW13 [229/326542]? Internal identifier in
Guarcello et al., 2013 (J/ApJ/773/135)
20- 28 F9.5 deg RAdeg Right ascension (J2000.0)
30- 37 F8.5 deg DEdeg Declination (J2000.0)
39- 43 F5.2 --- Stet [-0.11/15.64]? Stetson Variability Index
45 I1 --- Sx [0/2]? Stetson Index selection flag (1)
47 I1 --- Type [1/3]? Light-curve morphology type (2)
49 A1 --- Asymm [±] Light Curve Symetry (3)
51 I1 --- Disk [0/1]? Disk flag (4)
53- 58 F6.3 d Per ? Detected Period (5)
60 I1 --- Compound [1/5]? Compound flag (6)
62 I1 --- Slope [1]? Slope Flag (7)
64- 66 I3 --- nJ [0/107] Number of J observations
68- 70 I3 --- nH [0/104] Number of H observations
72- 74 I3 --- nK [0/104] Number of K observations
76- 80 F5.2 mag Jmag [10.45/18.83]? Median UKIRT/WFCAM J magnitude
82- 86 F5.2 mag Hmag [9.65/18.17]? Median UKIRT/WFCAM H magnitude
88- 92 F5.2 mag Kmag [9.15/17.47]? Median UKIRT/WFCAM K magnitude
94- 97 F4.2 mag e_Jmag [0.02/0.1]? Representative uncertainty in J
99-102 F4.2 mag e_Hmag [0.02/0.38]? Representative uncertainty in H
104-107 F4.2 mag e_Kmag [0.02/0.09]? Representative uncertainty in K
109-112 F4.2 mag J-H [0.23/3.54]? Median J-H color
114-117 F4.2 mag J-K [0.33/5.94]? Median J-K color
119-122 F4.2 mag H-K [0.06/2.4]? Median H-K color
124-127 F4.2 mag e_J-H [0.03/0.12]? Representative J-H uncertainty
129-132 F4.2 mag e_J-K [0.03/0.13]? Representative J-K uncertainty
134-137 F4.2 mag e_H-K [0.03/0.13]? Representative H-K uncertainty
139-142 F4.2 mag Jamp [0.02/1.79]? Peak-to-peak J amplitude
144-147 F4.2 mag Hamp [0.02/1.84]? Peak-to-peak H amplitude
149-152 F4.2 mag Kamp [0.02/1.61]? Peak-to-peak K amplitude
154-157 F4.2 mag J-Hamp [0.02/0.72]? Peak-to-peak J-H amplitude
159-162 F4.2 mag J-Kamp [0.01/1.08]? Peak-to-peak J-K amplitude
164-167 F4.2 mag H-Kamp [0.01/0.97]? Peak-to-peak H-K amplitude
169-172 F4.2 mag rmsJamp [0.02/1.29]? rms J amplitude
174-177 F4.2 mag rmsHamp [0.02/1.32]? rms H amplitude
179-182 F4.2 mag rmsKamp [0.02/1.14]? rms K amplitude
184-187 F4.2 mag rmsJ-Hamp [0.01/0.27]? rms J-H amplitude
189-192 F4.2 mag rmsJ-Kamp [0.01/0.39]? rms J-K amplitude
194-197 F4.2 mag rmsH-Kamp [0.01/0.35]? rms H-K amplitude
199-203 F5.1 deg IncKHK [-79.5/74.2]? The K,(H-K) slope
205-209 F5.1 deg IncJJH [-58.3/80.5]? The J,(J-H) slope
211-214 F4.1 deg IncJHHK [21/57.5]? The (J-H),(H-K) slope
216-218 F3.1 deg e_IncJHHK [0./0.8]? Uncertainty in IncJHHK
220-222 F3.1 deg e_IncKHK [0.5/9.4]? Uncertainty in IncKHK
224-226 F3.1 deg e_IncJJH [0.2/7.5]? Uncertainty in IncJJH
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Note (1): Stetson Index selection Flag as follows:
1 = Variable stars in the S1 sample with S>1
2 = Variable stars in the S2 sample with 0.25<S<1
- = Star was not variable in this survey
Note (2): Light-curve morphology type as follows:
1 = Periodic stars
2 = Other types of variability
3 = Occulation variable
Note (3): Light Curve Symetry as follows:
+ = If light-curve had burst asymmetry
- = If light-curve had dimming asymmetry
Note (4): Disk flag as follows:
0 = diskless
1 = disk-bearing
Note (5): Period measured in Roquette et al., 2017, J/A+A/603/A106.
Note (6): Compound flag as follows:
1 = Compound variable with a feature of distinct color
2 = Compound variable with variable IR-excess
3 = Compound variable with changing color-slope
5 = both 2 and 3
Note (7): Slope flag as follows:
1 = if the slope of the star's trajectories in the color-magnitude
and/or color-color diagram measured
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Byte-by-byte Description of file (#): lc/*
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Bytes Format Units Label Explanations
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1- 11 F11.5 d HJD-J ? J-band Julian date (HJD-2400000)
14- 18 F5.2 mag Jmag ? UKIRT/WFCAM J magnitude
21- 24 F4.2 mag e_Jmag ? rms uncertainty in Jmag
27- 35 F9.5 deg RAJdeg ? J-band right ascension (J2000)
38- 45 F8.5 deg DEJdeg ? J-band declination (J2000)
48- 58 F11.5 d HJD-H ? H-band Julian date (HJD-2400000)
61- 65 F5.2 mag Hmag ? UKIRT/WFCAM H magnitude
68- 71 F4.2 mag e_Hmag ? rms uncertainty in Hmag
74- 82 F9.5 deg RAHdeg ? H-band right ascension (J2000)
85- 92 F8.5 deg DEHdeg ? H-band declination (J2000)
95-105 F11.5 d HJD-K ? K-band Julian date (HJD-2400000)
108-112 F5.2 mag Kmag ? UKIRT/WFCAM K magnitude
115-118 F4.2 mag e_Kmag ? rms uncertainty in Kmag
121-129 F9.5 deg RAKdeg ? K-band right ascension (J2000)
132-139 F8.5 deg DEKdeg ? K-band declination (J2000)
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Acknowledgements:
Julia Roquette, jt574(at)exeter.ac.uk
References;
Roquette et al., Paper I 2017A&A...603A.106R 2017A&A...603A.106R, Cat. J/A+A/603/A106
(End) Julia Roquette [Univ. of Exeter, UK], Patricia Vannier [CDS] 17-Aug-2020