J/ApJ/888/L5 Transits, occultation times and RVs of WASP-12b (Yee+, 2020)
The orbit of WASP-12b is decaying.
Yee S.W., Winn J.N., Knutson H.A., Patra K.C., Vissapragada S., Zhang M.M.,
Holman M.J., Shporer A., Wright J.T.
<Astrophys. J., 888, L5 (2020)>
=2020ApJ...888L...5Y 2020ApJ...888L...5Y (SIMBAD/NED BibCode)
ADC_Keywords: Exoplanets; Photometry, infrared; Radial velocities
Keywords: Hot Jupiters; Exoplanets; Transit photometry
Abstract:
WASP-12b is a transiting hot Jupiter on a 1.09 day orbit around a
late-F star. Since the planet's discovery in 2008, the time interval
between transits has been decreasing by 29±2ms/yr. This is a
possible sign of orbital decay, although the previously available data
left open the possibility that the planet's orbit is slightly
eccentric and is undergoing apsidal precession. Here, we present new
transit and occultation observations that provide more decisive
evidence for orbital decay, which is favored over apsidal precession
by a ΔBIC of 22.3 or Bayes factor of 70000. We also present new
radial-velocity data that rule out the Romer effect as the cause of
the period change. This makes WASP-12 the first planetary system for
which we can be confident that the orbit is decaying. The decay
timescale for the orbit is P/{dot}P=3.25±0.23Myr. Interpreting the
decay as the result of tidal dissipation, the modified stellar tidal
quality factor is Q*'=1.8x105.
Description:
We observed 10 transits of WASP-12b with the 1.2m telescope at the
Fred Lawrence Whipple Observatory (FLWO) on Mt. Hopkins, Arizona,
between 2017 November and 2019 January. The observations were made
with Keplercam and a Sloan r'-band filter. See Section 2.
We observed four occultations of WASP-12b with the Spitzer Space
Telescope in 2019 January and February. The first and last event were
separated by 16 planetary orbits. All of the data were obtained with
the 4.5um channel. See Section 3.1.
An occultation of WASP-12b was also observed with the Wide-Field
Infrared Camera (WIRC) on the Hale 200 inch telescope at Palomar
Observatory on 2017 March 18. This observation was made in the Ks band.
See Section 3.2.
Knutson+ (2014, J/ApJ/785/126) presented radial-velocity measurements
of WASP-12 spanning about 6yr, using the High Resolution Echelle
Spectrometer (HIRES) on the Keck I telescope. As part of this
long-term program, we have obtained three new observations of WASP-12
extending the time baseline by 5yr. See Section 4.
We compiled all of the available transit and occultation times,
including the new data. Most of these times had already been compiled
by Patra+ (2017, J/AJ/154/4); we added 38 new transit times and 7 new
occultation times. See Section 5.
Objects:
---------------------------------------------------------------
RA (ICRS) DE Designation(s) Period
---------------------------------------------------------------
06 30 32.80 +29 40 20.3 WASP-12b = WASP-12b P=1.091419
---------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 34 9232 Photometric timeseries
table2.dat 72 7 New occultation midpoints and depths
table4.dat 29 72 HIRES radial velocity measurements
table5.dat 41 158 WASP-12b transit and occultation times
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See also:
J/ApJ/692/L9 : Tidal evolution of transiting exoplanets (Levrard+, 2009)
J/ApJ/709/168 : Eccentric orbits in exoplanets (Anglada-Escude+, 2010)
J/ApJ/720/872 : A spectropolarimetric analysis of WASP-12 (Fossati+, 2010)
J/ApJ/727/125 : Two secondary eclipses of WASP-12b with Spitzer (Campo+, 2011)
J/A+A/528/A65 : WASP-12b transits (Maciejewski+, 2011)
J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)
J/AJ/141/179 : Transits of TrES-4b, HAT-P-3b and WASP-12b (Chan+, 2011)
J/ApJ/745/77 : Photochemical model for planet WASP-12b (Kopparapu+, 2012)
J/ApJ/757/18 : RVs for 16 hot Jupiter host stars (Albrecht+, 2012)
J/ApJ/757/161 : Spectroscopy of 56 exoplanet host stars (Torres+, 2012)
J/A+A/551/A108 : Multi-site obs. of WASP-12 b transit (Maciejewski+, 2013)
J/ApJ/785/126 : HIRES radial velocity measurements (Knutson+, 2014)
J/A+A/588/L6 : WASP-12 transit light curves (Maciejewski+ 2016)
J/A+A/602/A107 : 231 transiting planets eccentricity and mass (Bonomo+, 2017)
J/AJ/154/4 : Times of transits and occultations of WASP-12b (Patra+, 2017)
J/AJ/155/165 : Dissipation in planet hosts from tidal spin-up (Penev+, 2018)
J/AJ/156/28 : Exoplanets with Spitzer light curves (Adams+, 2018)
J/AcA/68/371 : WASP and KELT planet transits (Maciejewski+, 2018)
J/MNRAS/486/5867 : Simulated Transit depths of 12 Hot Jupiters (Singh+, 2019)
J/A+A/628/A115 : WASP-12, CoRoT-1 and TrES-3 light curves (von Essen+, 2019)
J/A+A/630/A89 : WASP-12b and WASP-43b griz light curves (Parviainen+, 2019)
J/AJ/158/190 : MS hot Jupiter hosts with good astrometry (Hamer+, 2019)
J/AJ/159/150 : Transit times of 11 hot Jupiters (Patra+, 2020)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD Barycentric Julian Date; TDB
16- 21 F6.4 --- NFlux [0.96/1.03] Normalized flux
23- 28 F6.4 --- e_NFlux [0.001/0.005] The 1σ uncertainty in NFlux
30 A1 --- Tel Telescope code (1)
31- 34 I4 --- Orbit [1397/2026] Orbit number
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Note (1): Telescope as follows:
F = 1.2m telescope at the Fred Lawrence Whipple Observatory (FLWO) transit
observations (4935 occurrences),
S = Spitzer occultation observations (2573 occurrences),
W = WIRC on the Hale 200inch telescope occultation observations
(1724 occurrences).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 "Y/M/D" Date UT date
13- 16 I4 --- Orbit [1341/2026] Orbit number
18- 28 F11.5 d BJD [57769.5/58517.3] Midpoint in
Barycentric Julian Date TDB; BJD-2400000
30- 36 F7.5 d e_BJD [0.00074/0.0014] Timing uncertainty
38- 41 I4 ppm Depth [1089/4720] Eclipse depth
43- 45 I3 ppm e_Depth [71/279] Depth negative uncertainty
47- 49 I3 ppm E_Depth [72/289] Depth positive uncertainty
51- 57 A7 --- Source Instrument or reference
59 A1 --- r_Source [ab] Eclipse observed in another paper (1)
61- 65 A5 --- Band Observed photometric band
67- 69 F3.1 pix Ap [2/2.4]? Aperture radius
71- 72 I2 --- Bin [14/22]? Bin size (exposures)
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Note (1): Flag as follows:
a = Eclipse observed by H19: Hooton et al. (2019MNRAS.486.2397H 2019MNRAS.486.2397H)
b = Eclipse observed by V19: von Essen et al. (2019, J/A+A/628/A115)
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD Barycentric Julian Date; TDB
16- 23 F8.3 m/s RVel [-216/231] Radial velocity
25- 29 F5.3 m/s e_RVel [2/5] The 1σ uncertainty in RVel
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Event Event identifier (1)
5- 17 F13.5 d BJD Barycentric Julian date (TDB) of mid-observation
19- 25 F7.5 d e_BJD [0.0001/0.003] The 1σ uncertainty in BJD
27- 31 I5 --- Orbit [-1640/2026] Orbit number (2)
33- 41 A9 --- Ref Source code(s) (3)
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Note (1): Event as follows:
tra = Transit (139 occurrences)
occ = Occultation (19 occurrences)
Note (2): The transit of orbit -1640 observed by Hebb+ 2009ApJ...693.1920H 2009ApJ...693.1920H
was reanalyzed by Maciejewski+ 2013A&A...551A.108M 2013A&A...551A.108M
The occultation of orbit -722 observed by Deming+ 2015ApJ...805..132D 2015ApJ...805..132D
was reanalyzed by Patra+ 2017AJ....154....4P 2017AJ....154....4P
Note (3): Reference as follows:
H09 = Hebb et al. (2009ApJ...693.1920H 2009ApJ...693.1920H);
C13 = Copperwheat et al. (2013MNRAS.434..661C 2013MNRAS.434..661C);
C15 = Croll et al. (2016ApJ...802...28C 2016ApJ...802...28C);
C17 = Collins et al. (2017AJ....153...78C 2017AJ....153...78C);
Ca11 = Campo et al. (2011, J/ApJ/727/125);
Ch11 = Chan et al. (2011, J/AJ/141/179);
Co12 = Cowan et al. (2012ApJ...747...82C 2012ApJ...747...82C);
Cr12 = Crossfield et al. (2012ApJ...760..140C 2012ApJ...760..140C);
D15 = Deming et al. (2015ApJ...805..132D 2015ApJ...805..132D);
F13 = Fohring et al. (2013, J/A+A/551/A108);
H19 = Hooton et al. (2019MNRAS.486.2397H 2019MNRAS.486.2397H);
K15 = Kreidberg et al. (2015PASP..127.1161K 2015PASP..127.1161K);
M13 = Maciejewski et al. (2013, J/A+A/551/A108);
M16 = Maciejewski et al. (2011A&A...588L...6M 2011A&A...588L...6M);
M18 = Maciejewski et al. (2018, J/AcA/68/371);
O19 = Ozturk & Erdem (2019MNRAS.486.2290O 2019MNRAS.486.2290O);
P17 = Patra et al. (2017, J/AJ/154/4);
P19 = Patra et al. (2019, submitted);
S12 = Sada et al. (2012PASP..124..212S 2012PASP..124..212S);
S14 = Stevenson et al. (2014AJ....147..161S 2014AJ....147..161S);
V19 = von Essen et al. (2019, J/A+A/628/A115).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 23-Jun-2021