J/AcA/70/1     Photometric timeseries and timing data       (Maciejewski+, 2020)
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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 (2020)>
      =2020AcA....70..1M
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ADC_Keywords: Planets ; 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. 

File Summary:
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 FileName      Lrecl    Records    Explanations
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ReadMe            80          .   This file
wasp18lc.dat      42        524   A new light curve for a WASP-18 b's transit
h23tt.dat         36         80   Transit times for WASP-18 b
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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_TDB  Barycentric JD (1)
  12- 20 F9.6     .     Flux     Normalized flux
  21- 29 F9.6     .     Ferr     Flux error
  30- 36 A7       .     TelCode  Telescope code
  37- 42 A6       .     Filter   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-  4 I5       .     E        Transit number from initial epoch  
   5- 16 F13.6    d     Tmid     Mid-transit time (1)
  17- 25 F9.6     d     Err+     Mid-transit time positive uncertainty
  26- 34 F9.6     d     Err-     Mid-transit time negative uncertainty
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Note (1): Given as BJD 2400000+ in Barycentric Dynamical Time
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(End)      Gracjan Maciejewski [N.Copernicus University, Poland]     08-May-2020

