J/AJ/152/75 Photometric survey of IC 2391, η Cha, and USco (Oelkers+, 2016)
A wide-field survey for transiting Hot Jupiters and eclipsing pre-main-sequence
binaries in young stellar associations.
Oelkers R.J., Macri L.M., Marshall J.L., DePoy D.L., Lambas D.G.,
Colazo C., Stringer K.
<Astron. J., 152, 75 (2016)>
=2016AJ....152...75O 2016AJ....152...75O (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Clusters, open ; Stars, variable ;
Binaries, eclipsing ; Stars, pre-main sequence ; Stars, nearby ;
Stars, double and multiple ; Planets
Keywords: binaries: eclipsing - planets and satellites: detection -
stars: pre-main sequence
Abstract:
The past two decades have seen a significant advancement in the
detection, classification, and understanding of exoplanets and
binaries. This is due, in large part, to the increase in use of
small-aperture telescopes (<20cm) to survey large areas of the sky to
milli-mag precision with rapid cadence. The vast majority of the
planetary and binary systems studied to date consists of main-sequence
or evolved objects, leading to a dearth of knowledge of properties at
early times (<50Myr). Only a dozen binaries and one candidate
transiting Hot Jupiter are known among pre-main-sequence objects, yet
these are the systems that can provide the best constraints on stellar
formation and planetary migration models. The deficiency in the number
of well characterized systems is driven by the inherent and aperiodic
variability found in pre-main-sequence objects, which can mask and
mimic eclipse signals. Hence, a dramatic increase in the number of
young systems with high-quality observations is highly desirable to
guide further theoretical developments. We have recently completed a
photometric survey of three nearby (<150pc) and young (<50Myr) moving
groups with a small-aperture telescope. While our survey reached the
requisite photometric precision, the temporal coverage was
insufficient to detect Hot Jupiters. Nevertheless, we discovered 346
pre-main-sequence binary candidates, including 74 high-priority
objects for further study.
Description:
Our survey instrument, nicknamed AggieCam, consists of an Apogee Alta
F16M camera with a 4096*4096pixel Kodak KAD-16083 CCD that is
thermoelectrically cooled down to δT=-45°C relative to
ambient. Testing of the CCD showed a dark current of 0.2e-/pix/s at
temperatures of -25°C relative to ambient. The optics include a
Mamiya photographic 300mm lens with a Hoya UV and IR cut filter to
restrict the wavelength range to 0.4-0.7µm. The effective aperture
size of the telescope is 53.6mm and the total throughput of the system
is near 45%. The pixel scale of the detector is 6.2''/pix, leading to
a total field of view (hereafter FOV) of ∼50deg2. The telescope was
installed at the Estacion Astrofisica de Bosque Alegre (hereafter
EABA) as part of an ongoing collaboration with the Universidad
Nacional de Cordoba, which owns and operates the site.
EABA is a research and outreach observatory located at 31.412°S,
64.489°W at an altitude of 1350m, ∼50km from the city of Cordoba,
province of Cordoba, Argentina. Nearly all observations were carried
out remotely from the Mitchell Institute of Fundamental Physics and
Astronomy at Texas A&M University in College Station, Texas.
Logistical support for the instrument was provided by staff members of
the Instituto de Astronomia Teorica y Experimental, Observatorio de
Cordoba, and EABA.
We targeted three young stellar associations to maximize the science
return from our study: IC 2391 (α=8h40m,δ=-53°),
the η Chamaeleontis cluster
(ηCha,α=8h45m,δ=-79°), and the Upper Scorpius
association (USco,α=16h,δ=-24.5°).
Any transiting Hot Jupiter (HJ) or pre-main-sequence eclipsing binary
(PMB) candidate passing all of the significance tests described in
Sections 4.1 and 4.2 was then subject to a series of follow up
photometric observations. The 1.54m telescope at EABA provided 300+hr
of BVRI photometry to date, with further observations planned. The
0.8m telescope at the McDonald Observatory provided 14hr of BVRI
photometry. The Las Cumbres Global Observatory Telescope Network
(LCOGT) provided 30hr of gri photometry from their 1m facilities. The
Texas A&M University campus observatory 0.5m telescope provided 30hr
of gri photometry. Additionally, the 2.1m telescope at the McDonald
Observatory, coupled with the Sandiford Echelle Spectrograph provided
14hr of initial spectroscopic follow up during the Spring of 2015.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 68 294856 AggieCam stellar library
table4.dat 72 7 Hot Jupiter candidates
table6.dat 52 346 Pre-main-sequence eclipsing binary candidates
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See also:
J/AJ/151/166 : Stellar flares and variables from CSTAR (Oelkers+, 2016)
J/MNRAS/448/2737 : New PMS K/M Stars in Upper Scorpius (Rizzuto+, 2015)
J/AJ/149/50 : Photometry of 105 variable stars from CSTAR (Oelkers+, 2015)
J/AJ/146/139 : 2010 photometry of variable stars from Dome A (Wang+, 2013)
J/ApJ/758/31 : IR photometry for members of Upper Sco (Luhman+, 2012)
J/AJ/142/155 : Variable stars photometry from Dome A (Wang+, 2011)
J/MNRAS/355/959 : Proper motions of IC 2391 possible members (Dodd+, 2004)
J/AJ/124/404 : UScor OB association Lithium survey. II. (Preibisch, 2002)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name AggieCam identification of the star (G1)
9- 10 I2 h RAh Hour of Right Ascension from AggieCam (J2000)
12- 13 I2 min RAm Minute of Right Ascension from AggieCam (J2000)
15- 19 F5.2 s RAs Second of Right Ascension from AggieCam (J2000)
21 A1 --- DE- Sign of the Declination from AggieCam (J2000)
22- 23 I2 deg DEd Degree of Declination from AggieCam (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination from AggieCam (J2000)
28- 29 I2 arcsec DEs Arcsecond of Declination from AggieCam (J2000)
31- 36 F6.3 mag <Vmag> [0/16.8] Mean AggieCam V band magnitude (VAC)
38 I1 --- V [0/1] Metric for passing Variability testing in
Section 4.1 (0=fail, 1=pass) (1)
40 I1 --- P [0/1] Metric for passing Periodicity testing in
Section 4.1 (0=fail, 1=pass)
42 I1 --- E [0/1] Metric for passing Eclipse testing in
Section 4.2 (0=fail, 1=pass)
44- 53 F10.6 d Per-LS [0.1/435]? Period using Lomb-Scargle
periodogram (2)
55- 64 F10.6 d Per-BLS [0.2/5.9]? Period from Box-Least-Squares
algorithm (G2)
66- 68 A3 --- Class Classification of variable star from clustering
algorithm (3)
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Note (1): We employed a combination of three variability metrics following the
approach of Wang et al. 2013 (Cat. J/AJ/146/139) and Oelkers et al. 2015
(Cat. J/AJ/149/50). We only consider a star to be variable if it passes all
three of these metrics. See Section 4.1 for further details.
Note (2): Refer to Section 4.1 in the paper, and see also Lomb
1976Ap&SS..39..447L 1976Ap&SS..39..447L and Scargle 1982ApJ...263..835S 1982ApJ...263..835S.
Note (3): Stars were clustered into one of the types described in Section 5.1.1:
STU = short-term uniform periodic motion (i.e., RR Lyrae, contact,
semi-detached, and short-period detached binaries, sinusoidal
variables);
IRV = infrequent variability (i.e., possible flares, long-period detached
binaries, possible systematics);
STN = short-term non-uniform periodic;
LTU = long-term uniform variable;
LTN = long-term non-uniform variable;
TRN = transit candidate.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Name AggieCam identifier of the star (G1)
9- 10 I2 h RAh Hour of Right Ascension from AggieCam (J2000)
12- 13 I2 min RAm Minute of Right Ascension from AggieCam (J2000)
15- 18 F4.1 s RAs Second of Right Ascension from AggieCam (J2000)
20 A1 --- DE- Sign of the Declination from AggieCam (J2000)
21- 22 I2 deg DEd Degree of Declination from AggieCam (J2000)
24- 25 I2 arcmin DEm Arcminute of Declination from AggieCam (J2000)
27- 28 I2 arcsec DEs Arcsecond of Declination from AggieCam (J2000)
30- 37 F8.6 d Per-BLS [0.2/5.9] Period from Box-Least-Squares
algorithm (G2)
39- 48 F10.6 d TE-BLS [76.6/192.6] Ephemeris time in Julian Date from
Box-Least-Squares algorithm (JD-24546400)
50- 55 F6.3 mag <Vmag> [12.5/14.2] Mean AggieCam V band magnitude
(VAC)
57- 58 I2 mmag Depth [16/42] Eclipse depth
60- 72 A13 --- Obs Observatory for high precision photometric follow
up (Bosque Alegre, LCOGT, or K2) (1)
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Note (1): Source for photometry defined as below:
K2 = Archive photometry from the Campaign 2 mission of the
Kepler mission second/current phase (K2; Howell et al.
2014PASP..126..398H 2014PASP..126..398H);
LCOGT = Las Cumbres Global Observatory Telescope Network;
Bosque Alegre = Estacion Astrofisica de Bosque Alegre.
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Name AggieCam identification of the star (G1)
9- 10 I2 h RAh Hour of Right Ascension from AggieCam (J2000)
12- 13 I2 min RAm Minute of Right Ascension from AggieCam (J2000)
15- 19 F5.2 s RAs Second of Right Ascension from AggieCam (J2000)
21 A1 --- DE- Sign of the Declination from AggieCam (J2000)
22- 23 I2 deg DEd Degree of Declination from AggieCam (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination from AggieCam (J2000)
28- 29 I2 arcsec DEs Arcsecond of Declination from AggieCam (J2000)
31- 36 F6.3 mag <Vmag> [9.2/16.2] Mean AggieCam V band magnitude (VAC)
38- 46 F9.6 --- Per [0.2/24.5] Eclipse period in days
48 I1 --- ET [0/1] Metric for passing Eclipsing Test
(1=pass) (1)
50 I1 --- IR [0/3] Metric for passing IR excess test (2)
52 I1 --- PM [0/3] Metric for passing Proper Motion test (3)
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Note (1): Denotes stars with effective temperature and separations plausible at
the distance of the cluster (0=fail; 1=pass). See Section 5.3.3 for details
about testing viable binary component
Note (2): Denotes how many infrared excesses were identified in the 2MASS & WISE
photometry. See Section 5.3.1 for further details about color selections.
Note (3): Denotes stars with proper motions consistent with the moving group to
1-3σ (1=within 3σ; 2=within 2σ; 3=within 1σ).
Please refer to Section 5.3.2 for additional details about proper motions.
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Global Notes:
Note (G1): Prefix on star number defined as below:
CNNNNNN = Star in η Chamaeleontis cluster (η Cha);
UNNNNNN = Star in Upper Scorpius association (USco);
VNNNNNN = Star in IC 2391;
Note (G2): Refer to Section 4.2 in the paper, and see also Kovacs et al.
2002A&A...391..369K 2002A&A...391..369K.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 26-Sep-2016