J/A+A/641/A158 GTC transit light curves of WASP-69b (Murgas+, 2020)
The GTC exoplanet transit spectroscopy survey.
XI. Possible detection of Rayleigh scattering in the atmosphere of the
Saturn-mass planet WASP-69b.
Murgas F., Chen G., Nortmann L., Palle E., Nowak G.
<Astron. Astrophys. 641, A158 (2020)>
=2020A&A...641A.158M 2020A&A...641A.158M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Spectroscopy
Keywords: planets and satellites: atmospheres
Abstract:
One of the major atmospheric features in exoplanet atmospheres,
detectable both from ground- and space-based facilities, is Rayleigh
scattering. In hydrogen-dominated planetary atmospheres Rayleigh
scattering causes the measured planetary radius to increase towards
blue wavelengths in the optical range. We obtained a spectrophotometic
time series of one transit of the Saturn-mass planet WASP-69b using
the OSIRIS instrument at the Gran Telescopio Canarias. From the data
we construct 19 spectroscopic transit light curves representing 20nm
wide wavelength bins spanning from 515nm-905nm. We derive the
transit depth for each curve individually by fitting an analytical
model together with a Gaussian Processes to account for systematic
noise in the light curves. We find that the transit depth increases
towards bluer wavelengths, indicative of a larger effective planet
radius. Our results are consistent with space-based measurements
obtained in the near infrared using the Hubble Space telescope, which
show a compatible slope of the transmission spectrum. We discuss the
origin of the detected slope and argue between two possible scenarios:
a Rayleigh scattering detection originating in the planet's atmosphere
or a stellar activity induced signal from the host star.
Description:
We present here the transit light curves of the Saturn-mass exoplanet
WASP-69b obtained on October 5, 2016 using the 10.4-m GTC telescope.
The spectra were obtained using OSIRIS instrument in its long-slit
spectroscopy mode (40 arcsec slit, R1000R grism, wavelength coverage
515-905nm). We provide auxiliary parameters of the observations that
were use to detrend the original light curves. These parameters are:
airmass, position of the stars in spatial and dispersion direction,
the relative FWHM of the spectral profile in spatial and dispersion
direction, and telescope rotator angle. We also provide the
planet-to-star radius ratio measured from the spectrophotometric light
curves (tables A.1 and A.2 from the paper).
Objects:
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RA (2000) DE Designation(s)
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21 00 05.20 -05 05 40.04 WASP-69 = 2MASS J21000618-0505398
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 26 20 List of light curve files
gtcwlcn1.dat 95 590 WASP-69b GTC transit white light curve (2016/10/05)
lc/* . 19 Individual spectroscopic light curves (2016/10/05)
tablea1.dat 37 19 Results for the planet-to-star radius ratio for
each of the 19 spectroscopic channels
tablea2.dat 37 11 Results for the planet-to-star radius ratio for
each of the 11 spectroscopic channels around the
NaI doublet
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See also:
J/A+A/563/A41 : WASP-43 OSIRIS transmission spectroscopy (Murgas+, 2014)
J/A+A/589/A62 : GTC transit light curves of CoRoT-29b (Palle+, 2016)
J/A+A/594/A65 : GTC transit light curves of HAT-P-32b (Nortmann+, 2016)
J/A+A/600/L11 : GTC transit light curves of WASP-52b (Chen+, 2017)
J/A+A/605/A114 : GTC transit light curves of WASP-48b (Murgas+, 2017)
J/A+A/616/A145 : GTC transit light curves of WASP-127b (Chen+, 2018)
J/A+A/622/A172 : GTC transit light curves of HAT-P-11b (Murgas+, 2019)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Range Wavelength interval in nm
13- 26 A14 --- FileName Name of the table with photometry
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Byte-by-byte Description of file: gtcwlcn1.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d BJD Barycentric Julian Date (TDB standard)
18- 25 F8.6 --- Flux Relative flux
27- 34 F8.6 --- e_Flux Uncertainty of relative flux
36- 44 F9.6 pix posX Drift of star on CCD in spatial direction
46- 54 F9.6 pix posY Drift of star on CCD in dispersion direction
56- 64 F9.6 pix fwhmX Relative change of full width at half maximum
of the stellar absorption line profile
66- 75 F10.6 pix fwhmY Full width at half maximum of the stellar
spatial profile
77- 84 F8.6 --- Airm Airmass during observation
86- 95 F10.6 deg RotAng Telescope rotator angle during observations
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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- 5 F5.1 nm lambda1 Wavelength of the left border of the channel
7- 11 F5.1 nm lambda2 Wavelength of the right border of the channel
13- 28 F16.8 d BJD Barycentric Julian Date (TDB standard)
30- 37 F8.6 --- Flux Relative flux
39- 46 F8.6 --- e_Flux Uncertainty of relative flux
48- 56 F9.6 pix posX Drift of star on CCD in spatial direction
58- 66 F9.6 pix posY Drift of star on CCD in dispersion direction
68- 76 F9.6 pix fwhmX Relative change of full width at half maximum
of the stellar absorption line profile
78- 87 F10.6 pix fwhmY Full width at half maximum of the stellar
spatial profile
89- 96 F8.6 --- Airm Airmass during observation
98-107 F10.6 deg RotAng Telescope rotator angle during observations
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Byte-by-byte Description of file: tablea1.dat tablea2.dat
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Bytes Format Units Label Explanations
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1- 5 F5.1 nm lambda1 Wavelength of the center of the channel
7- 10 F4.1 nm lambda2 Total width of the channel
12- 19 F8.6 --- Rp/Rs Measured planet-to-star radius ratio Rp/Rs
21- 28 F8.6 --- E_Rp/Rs Upper 1-sigma uncertainty in Rp/Rs
30- 37 F8.6 --- e_Rp/Rs Lower 1-sigma uncertainty in Rp/Rs
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Acknowledgements:
Felipe Murgas, fmurgas(at)iac.es
References:
Murgas et al., Paper I 2014A&A...563A..41M 2014A&A...563A..41M, Cat. J/A+A/563/A41
Parviainen et al., Paper II 2016A&A...585A.114P 2016A&A...585A.114P
Palle et al., Paper III 2016A&A...589A..62P 2016A&A...589A..62P, Cat. J/A+A/589/A62
Nortmann et al., Paper IV 2016A&A...594A..65N 2016A&A...594A..65N, Cat. J/A+A/594/A65
Chen et al., Paper V 2017A&A...600A.138C 2017A&A...600A.138C
Chen et al., Paper VI 2017A&A...600L..11C 2017A&A...600L..11C, Cat. J/A+A/600/L11
Murgas et al., Paper VII 2017A&A...605A.114M 2017A&A...605A.114M, Cat. J/A+A/605/A114
Parviainen et al., Paper VIII 2018A&A...609A..33P 2018A&A...609A..33P
Chen et al., Paper IX 2018A&A...616A.145C 2018A&A...616A.145C, Cat. J/A+A/616/A145
Murgas et al., Paper X. 2019A&A...622A.172M 2019A&A...622A.172M, Cat. J/A+A/622/A172
(End) Felipe Murgas [IAC], Patricia Vannier [CDS] 08-Jul-2020