J/MNRAS/454/3094 Optical transit light curves of WASP-57 (Southworth+, 2015)
Larger and faster: revised properties and a shorter orbital period for
the WASP-57 planetary system from a pro-am collaboration.
Southworth J., Mancini L., Tregloan-Reed J., Calchi Novati S., Ciceri S.,
D'Ago G., Delrez L., Dominik M., Evans D.F., Gillon M., Jehin E.,
Jorgensen U.G., Haugbolle T., Lendl M., Arena C., Barbieri L., Barbieri M.,
Corfini G., Lopresti C., Marchini A., Marino G., Alsubai K.A., Bozza V.,
Bramich D.M., Figuera Jaimes R., Hinse T.C., Henning TH., Hundertmark M.,
Juncher D., Korhonen H., Popovas A., Rabus M., Rahvar S., Schmidt R.W.,
Skottfelt J., Snodgrass C., Starkey D., Surdej J., Wertz O.
<Mon. Not. R. Astron. Soc., 454, 3094-3107 (2015)>
=2015MNRAS.454.3094S 2015MNRAS.454.3094S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Photometry, ugriz
Keywords: stars: fundamental parameters - stars: individual: WASP-57 -
planetary systems
Abstract:
Transits in the WASP-57 planetary system have been found to occur half
an hour earlier than expected. We present 10 transit light curves from
amateur telescopes, on which this discovery was based, 13 transit
light curves from professional facilities which confirm and refine
this finding, and high-resolution imaging which show no evidence for
nearby companions. We use these data to determine a new and precise
orbital ephemeris, and measure the physical properties of the system.
Our revised orbital period is 4.5 s shorter than found from the
discovery data alone, which explains the early occurrence of the
transits. We also find both the star and planet to be larger and less
massive than previously thought. The measured mass and radius of the
planet are now consistent with theoretical models of gas giants
containing no heavy-element core, as expected for the subsolar
metallicity of the host star. Two transits were observed
simultaneously in four passbands. We use the resulting light curves to
measure the planet's radius as a function of wavelength, finding that
our data are sufficient in principle but not in practise to constrain
its atmospheric properties. We conclude with a discussion of the
current and future status of transmission photometry studies for
probing the atmospheres of gas-giant transiting planets.
Description:
Two complete transits of WASP-57 were observed using the 1.54 m Danish
Telescope and DFOSC instrument at ESO La Silla, Chile (see Dominik et al.
2010AN....331..671D 2010AN....331..671D), on the dates 2014/05/18 and 2014/06/24. Both transits
were obtained through a Bessell R filter.
The transit on 2014/06/24 observed with DFOSC was also monitored using
GROND (Greiner et al. 2008PASP..120..405G 2008PASP..120..405G) mounted on the MPG 2.2 m
telescope at La Silla, Chile. GROND was used to obtain light curves
simultaneously in four passbands, which approximate the SDSS g, r, i and z
bands.
We observed WASP-57 on the night of 2012/05/10 using the BUSCA instrument
on the 2.2 m telescope at Calar Alto Astronomical Observatory. BUSCA
is capable of observing simultaneously in four passbands, for which we
chose Gunn u, g, r and z.
One transit of WASP-57 was observed on 2012/04/01 with EulerCam, using
the same methods as for the EulerCam transit in Faedi et al. (2013,
J/A+A/551/A73). We obtained 212 images through a Gunn r filter, without
applying a defocus to the instrument.
Two transits of WASP-57 were observed on 2012/03/15 and 2012/04/01 using
the 0.6 m TRAPPIST robotic telescope located at La Silla (Gillon et al.
2011EPJWC..1106002G 2011EPJWC..1106002G; Jehin et al. 2011Msngr.145....2J 2011Msngr.145....2J). Images were
obtained with a slight defocus and through a blue-blocking filter that has
a transmittance greater than 90 per cent from 500 nm to beyond 1000 nm.
Objects:
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RA (ICRS) DE Designation(s)
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14 55 16.82 -02 03 27.5 WASP-57 = GSC 04991-00565
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 47 2189 Defocussed photometry for the transiting
extrasolar planetary system WASP-57
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See also:
J/ApJ/707/167 : Transiting planetary system WASP-18 (Southworth+, 2009)
J/MNRAS/396/1023 : Transiting planetary system WASP-5 (Southworth+, 2009)
J/MNRAS/399/287 : Transiting planetary system WASP-4 (Southworth+, 2009)
J/MNRAS/408/1680 : Transiting planetary system WASP-2 (Southworth+, 2010)
J/A+A/527/A8 : Transiting planetary system WASP-7 (Southworth+, 2011)
J/MNRAS/426/1338 : Transiting planetary system WASP-17 (Southworth+, 2012)
J/A+A/562/A126 : Light curves of WASP-80 transit events (Mancini+, 2014)
J/A+A/568/A127 : Light curves of WASP-67 transit events (Mancini+, 2014)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Inst Instrument used for observation
10- 11 A2 --- Filter [ugriz R bb] Filter
13- 26 F14.6 d BJD Barycentric Julian Date (TDB)
28- 37 F10.7 mag Dmag Differencial magnitude in Filter
39- 47 F9.7 mag e_Dmag Uncertainty in Dmag
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 19-Jan-2018