J/ApJ/736/12 Transit light curves of GJ1214 (Berta+, 2011)
The GJ1214 super-Earth system: stellar variability, new transits, and a search
for additional planets.
Berta Z.K., Charbonneau D., Bean J., Irwin J., Burke C.J., Desert J.-M.,
Nutzman P., Falco E.E.
<Astrophys. J., 736, 12 (2011)>
=2011ApJ...736...12B 2011ApJ...736...12B
ADC_Keywords: Photometry ; Planets ; Stars, M-type ; Stars, double and multiple
Keywords: brown dwarfs - eclipses - stars: individual (GJ 1214) -
planets and satellites: individual (GJ 1214b) - stars: low-mass -
stars: rotation - starspots
Abstract:
The super-Earth GJ1214b transits a nearby M dwarf that exhibits a 1%
intrinsic variability in the near-infrared. Here, we analyze new
observations to refine the physical properties of both the star and
planet. We present three years of out-of-transit photometric
monitoring of the stellar host GJ1214 from the MEarth Observatory and
find the rotation period to be long, most likely an integer multiple
of 53 days, suggesting low levels of magnetic activity and an old age
for the system. We show that such variability will not pose
significant problems to ongoing studies of the planet's atmosphere
with transmission spectroscopy. We analyze two high-precision transit
light curves from ESO's Very Large Telescope (VLT) along with seven
others from the MEarth and Fred Lawrence Whipple Observatory 1.2m
telescopes, finding physical parameters for the planet that are
consistent with previous work. The VLT light curves show tentative
evidence for spot occultations during transit. Using two years of
MEarth light curves, we place limits on additional transiting planets
around GJ1214 with periods out to the habitable zone of the system. We
also improve upon the previous photographic V-band estimate for the
star, finding V=14.71±0.03.
Description:
We monitored the brightness of the GJ1214 system at a variety of
cadences with the MEarth Observatory at Mt. Hopkins, AZ, throughout
the 2008, 2009, and 2010 spring observing seasons. For the bulk of the
data presented in this work telescopes were equipped with a fixed,
custom, 715nm long-pass filter; the response is similar to a
combination of the Sloan i+z bandpasses. In Table 1, we present one
new MEarth transit light curve along with the four MEarth and two
KeplerCam light curves that were analyzed but not made electronically
available in Charbonneau et al. (2009Natur.462..891C 2009Natur.462..891C).
Spectra of GJ1214 and six comparison stars were gathered during three
transits of GJ1214b using ESO Director's Discretionary Time on the VLT
(Program ID 284.C-5042 and 285.C-5019) with FORS2 in 2010 Apr 29 and
2010 May 18.
Objects:
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RA (2000) DE Designation(s) (Period)
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17 15 18.94 +04 57 49.7 GJ 1214 = USNO-B1.0 0949-00280047 (P=1.580404)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 52 1393 Transit light curves
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See also:
I/298 : LSPM-North Catalog (Lepine+ 2005)
J/AJ/141/166 : HATNet variability survey of K and M dwarfs (Hartman+, 2011)
J/other/A+ARV/17.251 : Stars observed with Doppler imaging (Strassmeier, 2009)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/A+A/487/373 : Spectroscopic parameters of 451 HARPS-GTO stars (Sousa+, 2008)
J/ApJ/622/1102 : The planet-metallicity correlation (Fischer+, 2005)
J/A+A/331/581 : Rotation and activity in field M dwarfs (Delfosse+ 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 F15.7 d BJD Baryocentric Julian Date of mid-exposure (1)
17- 23 F7.5 --- Flux Relative flux (2)
25- 31 F7.5 --- e_Flux The 1σ uncertainty in Flux (3)
33- 38 F6.4 --- Airmass Airmass
40- 45 A6 --- Inst Telescope system used (FLWO, MEARTH or VLT) (5)
47- 52 I6 --- Cycle Number of periods elapsed (4)
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Note (1): In the Barycentric Dynamical Time system (Eastman et al.
2010PASP..122..935E 2010PASP..122..935E).
Note (2): Differential photometry corrections have been applied, but additional
systematic corrections (see text) have not. Each light curve has been
divided by the median out-of-transit flux.
Note (3): Calculated from a standard CCD noise model.
Note (4): Time measured from the reference epoch in units of the orbital period.
Note (5): Telescopes:
FLWO = Fred Lawrence Whipple Observatory (Arizona)
MEARTH = MEarth, array of eight 40-cm optical reflector telescopes
VLT = Very Large Telescope at ESO
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Dec-2012