J/A+A/620/A142 HAT-P-12b 2016-2017 light curve (Alexoudi+, 2018)
Deciphering the atmosphere of HAT-P-12b: solving discrepant results.
Alexoudi X., Mallonn M., von Essen C., Turner J.D., Keles E.,
Southworth J., Mancini L., Ciceri S., Granzer T., Denker C., Dineva E.,
Strassmeier K.G.
<Astron. Astrophys. 620, A142 (2018)>
=2018A&A...620A.142A 2018A&A...620A.142A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, K-type ; Planets ;
Photometry, CCD
Keywords: planets and satellites: gaseous planets -
planets and satellites: atmospheres - stars: individual: HAT-P-12
Abstract:
Two independent investigations of the atmosphere of the hot Jupiter
HAT-P-12b by two different groups resulted in discrepant solutions.
Using broad-band photometry from the ground, one study found a flat
and featureless transmission spectrum which was interpreted as a gray
absorption by dense cloud coverage.
The second study made use of the Hubble Space Telescope (HST)
observations and found Rayleigh scattering at optical wavelengths
caused by haze. The main purpose of this work is to find the source of
this inconsistency and provide feedback to prevent similar
discrepancies in future analyses of other exoplanetary atmospheres.
We studied the observed discrepancy via two methods. With further
broad-band observations in the optical wavelength regions, we
strengthened the previous measurements in precision and with a
homogeneous reanalysis of the published data, we managed to assess the
systematic errors and the independent analyses of the two different
groups. Repeating the analysis steps of both works, we found that
deviating values for the orbital parameters are the reason for the
aforementioned discrepancy.
Our work showed a degeneracy of the planetary spectral slope with
these parameters. In a homogeneous reanalysis of all data, the two
literature data sets and the new observations converge to a consistent
transmission spectrum, showing a low-amplitude spectral slope and a
tentative detection of potassium absorption.
Description:
Photometric observations of the transiting exoplanet HAT-P-12b in
2016-2017 with different ground-based facilities. These observations
made use of the 1.2m STELLA robotic telescope (5 transits at Sloan g'),
the 3.5m Telescopio Nazionale Galileo (TNG) on Roque de los Muchachos
Observatory (1 transit at Johnson B), the 1.23m (two transits at
Johnson B) and 2.2m (1 transit at Johnson B) telescopes of Calar Alto
Observatory and the 3.5m (1 transit at Johnson B) Astrophysics
Research Consortium (ARC) telescope from the Apache Point Observatory.
Objects:
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RA (2000) DE Designation(s)
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13 57 33.47 +43 29 36.6 HAT-P-12 = 2MASS J13573347+4329367
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 10 Overview of the new observations of transits of
HAT-P-12b during 2016 and 2017
hatp12b.dat 70 1595 Broadband photometry of HAT-P-12b
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See also:
J/ApJ/706/785 : HAT-P-12 light curve (Hartman+, 2009)
J/AJ/143/95 : Transit light curves of HAT-P-12 (Lee+, 2012)
J/AJ/152/88 : Spectroscopy and photometry of HATS-11 & HATS-12 (Rabus+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 "date" Date Observation date
13- 28 A16 --- Tel Telescope
30- 31 A2 --- Filt Filter
33- 35 I3 s Texp Exposure time
37- 39 I3 --- Ndata Number of individual data points
41- 46 F6.4 mag rms Scatter of the data points as root-mean-square
(rms) of the light curve residuals
48- 51 F4.2 --- beta beta factor
53- 65 F13.7 d MJD1 Modified, barycentric Julian Date of first
measurement
66 A1 --- --- [-]
67- 79 F13.7 d MJD2 Modified, barycentric Julian Date of last
measurement
81- 82 I2 --- Trans [1/10] Transit number
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Byte-by-byte Description of file: hatp12b.dat
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Bytes Format Units Label Explanations
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1- 5 F5.1 nm lambda Effective central wavelength (1)
8- 12 F5.1 nm FWHM Wavelength FWHM
15- 27 F13.7 d MJD Modified, barycentric Julian Date
(Julian Date - 2400000.5)
30- 38 F9.7 --- Flux Normalized relative flux
41- 49 F9.7 --- e_Flux Uncertainty on relative flux
52- 67 A16 --- Tel Telescope name (1)
69- 70 I2 --- Trans [1/10] Transit number
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Note (1): Telescopes and wavelengths:
1.23m Calar Alto (B, 448.5nm) 2 transits, 2.2m Calar Alto (B, 451.1nm)
1 transit, ARC (B, 434.0nm) 1 transit, STELLA (g', 475.4nm) 5 transits and
TNG (B, 436.0nm) 1 transit.
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Acknowledgements:
Xanthippi Alexoudi, xalexoudi(at)aip.de,
Leibniz Institute for Astrophysics Potsdam
(End) Xanthippi Alexoudi [AIP], Patricia Vannier [CDS] 11-Oct-2018