J/AcA/70/1 WASP-18 Photometric timeseries and timing data (Maciejewski+, 2020)
Planet-star interactions with precise transit timing. II. The radial-velocity
tides and a tighter constraint on the orbital decay rate in the WASP-18 system.
Maciejewski G., Knutson H. A., Howard A. W., Isaacson H.,
Fernandez-Lajus E., Di Sisto R. P., Migaszewski C.
<Acta Astron. 70, 1-18 (2020)>
=2020AcA....70....1M 2020AcA....70....1M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry, CCD
Keywords: planet-star interactions - stars: individual: WASP-18 -
planets and satellites: individual: WASP-18 b
Abstract:
From its discovery, the WASP-18 system with its massive transiting
planet on a tight orbit was identified as a unique laboratory for
studies on tidal planet-star interactions. In an analysis of Doppler
data, which include five new measurements obtained with the
HIRES/Keck-I instrument between 2012 and 2018, we show that the radial
velocity signal of the photosphere following the planetary tidal
potential can be distilled for the host star. Its amplitude is in
agreement with both theoretical predictions of the equilibrium tide
approximation and an ellipsoidal modulation observed in an orbital
phase curve. Assuming a circular orbit, we refine system parameters
using photometric time series from TESS. With a new ground-based
photometric observation, we extend the span of transit timing
observations to 28 years in order to probe the rate of the orbital
period shortening. Since we found no departure from a constant-period
model, we conclude that the modified tidal quality parameter of the
host star must be greater than 3.9e6 with 95% confidence. This result
is in line with conclusions drawn from studies of the population of
hot Jupiters, predicting that the efficiency of tidal dissipation is 1
or 2 orders of magnitude weaker. As the WASP-18 system is one of the
prime candidates for detection of orbital decay, further timing
observations are expected to push the boundaries of our knowledge on
stellar interiors.
Description:
We provide (1) a new light curve for a transit of the WASP-18 b
exoplanet observed on September 26, 2019 with the 0.6 m Helen Sawyer
Hogg (HSH) telescope located at Complejo Astronomico El Leoncito
(Argentina) and (2) mid-transit times presented in Table 3 of the
source paper.
Objects:
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RA (2000) DE Designation(s)
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01 37 25.03 -45 40 40.3 WASP-18 = HD 10069
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
wasp18lc.dat 38 524 A new light curve for a WASP-18 b's transit
wasp18tt.dat 36 80 Transit times for WASP-18 b
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See also:
J/ApJ/707/167 : Transiting planetary system WASP-18 (Southworth+, 2009)
J/AcA/68/371 : WASP and KELT planet transits (Maciejewski+, 2018)
Byte-by-byte Description of file: wasp18lc.dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 d BJD Barycentric Julian date, TDB (BJD-2450000) (1)
12- 20 F9.6 --- Flux Normalized flux
21- 29 F9.6 --- e_Flux Flux error
31- 36 A6 --- Tel Telescope code (HSH0.6)
38 A1 --- Filter [I] Filter name
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Note (1): Given as BJD 2450000+ in Barycentric Dynamical Time
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Byte-by-byte Description of file: wasp18tt.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- E Transit number from the initial epoch
6- 18 F13.6 d Tmid Mid-transit time, BJD-2400000 (1)
19- 27 F9.6 d E_Tmid Mid-transit time upper uncertainty
28- 36 F9.6 d e_Tmid Mid-transit time lower uncertainty
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Note (1): Given as BJD 2400000+ in Barycentric Dynamical Time.
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Acknowledgements:
Gracjan Maciejewski, gmac(at)umk.pl
Institute of Astronomy, Nicolaus Copernicus University, Poland
References:
Maciejewski et al., Paper I 2018AcA....68..371M 2018AcA....68..371M, Cat. J/AcA/68/371
(End) Gracjan Maciejewski [Copernicus Univ.], Patricia Vannier [CDS] 12-Jun-2020