J/ApJ/893/L29 WASP-4 RVs & hot Jupiter predicted period changes (Bouma+, 2020)
WASP-4 is accelerating toward the Earth.
Bouma L.G., Winn J.N., Howard A.W., Howell S.B., Isaacson H., Knutson H.,
Matson R.A.
<Astrophys. J., 893, L29 (2020)>
=2020ApJ...893L..29B 2020ApJ...893L..29B (SIMBAD/NED BibCode)
ADC_Keywords: Exoplanets; Radial velocities; Optical
Keywords: Exoplanet tides; Exoplanet dynamics; Radial velocity
Transit timing variation method
Abstract:
The orbital period of the hot Jupiter WASP-4b appears to be decreasing
at a rate of -8.64±1.26ms/yr, based on transit-timing measurements
spanning 12yr. Proposed explanations for the period change include
tidal orbital decay, apsidal precession, and acceleration of the
system along the line of sight. To investigate further, we performed
new radial-velocity measurements and speckle imaging of WASP-4. The
radial-velocity data show that the system is accelerating toward the
Sun at a rate of -0.0422±0.0028m/s/day. The associated Doppler
effect should cause the apparent period to shrink at a rate of
-5.94±0.39ms/yr, comparable to the observed rate. Thus, the observed
change in the transit period is mostly or entirely produced by the
line-of-sight acceleration of the system. This acceleration is
probably caused by a wide-orbiting companion of mass 10-300MJup and
orbital distance 10-100au, based on the magnitude of the
radial-velocity trend and the nondetection of any companion in the
speckle images. We expect that the orbital periods of one out of three
hot Jupiters will change at rates similar to WASP-4b, based on the
hot-Jupiter companion statistics of Knutson et al. Continued
radial-velocity monitoring of hot Jupiters is therefore essential to
distinguish the effects of tidal orbital decay or apsidal precession
from line-of-sight acceleration.
Description:
Table 1 lists the transit times we collected for our analysis. Most of
these data are identical to the data presented by B19
(Bouma+, 2019, J/AJ/157/217).
Twenty-two new times reported by Southworth+ (2019, J/MNRAS/490/4230)
are included. These transits were observed from the 3.58m New
Technology Telescope and the Danish 1.54m telescope at La Silla,
Chile, and the South African Astronomical Observatory 1.0m telescope.
See Section 2.1.
We acquired four new radial-velocity measurements with the Keck I 10m
telescope and the High Resolution Echelle Spectrometer (HIRES). In
doing so, we extended the time baseline of HIRES measurements from
3 to 9yr. See Section 2.2.
We performed speckle imaging with the Zorro instrument on the Gemini
South 8m telescope. We observed WASP-4 twice, on the night of
September 11-12 with relatively poor seeing (1.2") and also on the
night of 2019 September 28-29. See Section 2.3.
Objects:
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RA (ICRS) DE Designation(s) (Per)
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23 34 15.09 -42 03 41.0 WASP-4 = TYC 8017-108-1 (P=1.3382314)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 95 93 WASP-4b transit times
table2.dat 55 48 WASP-4 radial velocities
table5.dat 104 51 Predicted hot Jupiter period changes from linear
radial velocity trends reported by
Knutson+ 2014, J/ApJ/785/126
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJS/152/261 : Chromospheric Ca II emission in nearby stars (Wright+, 2004)
J/MNRAS/399/287 : Transiting planetary system WASP-4 (Southworth+, 2009)
J/ApJ/692/L9 : Tidal evolution of transiting exoplanets (Levrard+, 2009)
J/AJ/137/3826 : Two transits of the giant planet WASP-4b (Winn+, 2009)
J/ApJ/696/1950 : Sloan iz light curves of HAT-P-10 (Bakos+, 2009)
J/A+A/524/A25 : Radial Velocities on 6 exoplanet host stars (Triaud+, 2010)
J/ApJ/733/127 : Four transits of WASP-4b (Sanchis-Ojeda+, 2011)
J/MNRAS/414/1278 : Eccentricities of transiting planets (Pont+, 2011)
J/AJ/142/19 : Speckle observations of KOI (Howell+, 2011)
J/A+A/530/A5 : WASP-4b thermal emission, Ks-band (Caceres+, 2011)
J/A+A/539/A159 : WASP-4b transit griz light curves (Nikolov+, 2012)
J/ApJ/785/126 : HIRES radial velocity measurements (Knutson+, 2014)
J/ApJ/800/22 : Radial velocities of long-period planets (Feng+, 2015)
J/ApJ/806/248 : AO imaging of KOIs with gas giant planets (Wang+, 2015)
J/A+A/588/L6 : WASP-12 transit light curves (Maciejewski+ 2016)
J/ApJ/821/89 : 12yrs of RVel obs. of exoplanet systems (Bryan+, 2016)
J/AJ/152/8 : Impact of stellar multiplicity on planets I. (Kraus+, 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 exoplanet hosts (Penev+, 2018)
J/AJ/155/255 : RVel and activity measurements of HAT-P-11 (Yee+, 2018)
J/AJ/156/18 : Binary companions of evolved stars (Price-Whelan+, 2018)
J/AJ/156/216 : Differential photometry & RVs of HATS-59 (Sarkis+, 2018)
J/AcA/68/371 : WASP and KELT planet transits (Maciejewski+, 2018)
J/AJ/157/52 : Radial velocity obs. in super-Earth systems (Bryan+, 2019)
J/AJ/157/217 : Transit times of 5 hot Jupiter WASP exoplanets (Bouma+, 2019)
J/AJ/158/190 : Astrometry of main sequence hot Jupiter hosts (Hamer+, 2019)
J/MNRAS/490/4230 : Transiting planet WASP-4b (Southworth+, 2019)
J/MNRAS/490/5088 : Stellar companions of exoplanet host stars (Mugrauer, 2019)
J/AJ/159/19 : SOAR TESS survey. I. (Ziegler+, 2020)
J/ApJ/888/L5 : Transits, occultation times and RVs of WASP-12b (Yee+, 2020)
J/A+A/636/A74 : HARPS radial velocity database (Trifonov+, 2020)
J/AJ/159/150 : Transit times of 11 hot Jupiters (Patra+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Transit mid-time, ttra, in BJD TDB
16- 23 F8.6 d e_BJD [5e-05/0.001] The 1σ uncertainty in BJD
25- 29 I5 --- Epoch [-1354/1848] Transit number
31- 71 A41 --- Ref Who first processed the light-curves (1)
73- 95 A23 --- r_BJD Provence of transit mid-time (1)
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Note (1): The "Ref" and "r_BJD" columns can be different in cases when the
light-curves were homogeneously reprocessed after they were originally
reported in the literature. The format of these columns is usually ADS
bibcodes, unless further clarification in the format of a string is
required.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 d BJD Time in BJD TDB; BJD-2450000
13- 23 F11.6 m/s RV [-299/264] Mean subtracted radial velocity
per instrument
25- 33 F9.6 m/s e_RV [1.7/25.4] Uncertainty in RV
35- 42 F8.6 --- Sind [0.17/0.26]? Chromospheric S-index;
blank if NaN
44- 50 A7 --- Tel Instrument name
52- 55 A4 --- Ref Data source (1)
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Note (1): Provenance key is as follows:
T+10 = Triaud+ 2010, J/A+A/524/A25
P+11 = Pont+ 2011, J/MNRAS/414/1278
B+20 = This work.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Planet name
12- 19 F8.5 m/s/yr dRV/dt [-0.097/0.08] Measured d(RV)/dt
21- 28 F8.5 m/s/yr E_dRV/dt [0/0.058] Upper 84-50 uncertainty in dRV/dt
30- 37 F8.5 m/s/yr e_dRV/dt [0/0.058] Lower 50-16 uncertainty in dRV/dt
39- 47 F9.6 d Per [0.78/10.9] Planet orbital period
from NASA's Exoplanet Archive
49- 55 F7.3 ms/yr dP/dt [-55.63/40.76] Doppler predicted dP/dt
57- 62 F6.3 ms/yr E_dP/dt [0/41.96] Upper 84-50 uncertainty in dP/dt
64- 69 F6.3 ms/yr e_dP/dt [0/41.96] Lower 50-16 uncertainty in dP/dt
71- 71 I1 --- Sig [0/1] Is d(RV)/dt >3sigma significant?
73-104 A32 --- Comm Comment
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 09-Sep-2021