J/AJ/154/237 HARPS-N radial velocities of WASP-47 (Vanderburg+, 2017)
Precise masses in the WASP-47 system.
Vanderburg A., Becker J.C., Buchhave L.A., Mortier A., Lopez E.,
Malavolta L., Haywood R.D., Latham D.W., Charbonneau D., Lopez-Morales M.,
Adams F.C., Bonomo A.S., Bouchy F., Cameron A.C., Cosentino R.,
Di Fabrizio L., Dumusque X., Fiorenzano A., Harutyunyan A., Johnson J.A.,
Lorenzi V., Lovis C., Mayor M., Micela G., Molinari E., Pedani M., Pepe F.,
Piotto G., Phillips D., Rice K., Sasselov D., Segransan D., Sozzetti A.,
Udry S., Watson C.
<Astron. J., 154, 237-237 (2017)>
=2017AJ....154..237V 2017AJ....154..237V (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Exoplanets ; Spectroscopy ;
Radial velocities
Keywords: planets and satellites: composition -
planets and satellites: detection -
planets and satellites: dynamical evolution and stability -
planets and satellites: fundamental parameters -
planets and satellites: gaseous planets -
planets and satellites: interiors
Abstract:
We present precise radial velocity observations of WASP-47, a star known
to host a hot Jupiter, a distant Jovian companion, and, uniquely, two
additional transiting planets in short-period orbits: a super-Earth in
a ∼19 hr orbit, and a Neptune in a ∼9 day orbit. We analyze our
observations from the HARPS-N spectrograph along with previously
published data to measure the most precise planet masses yet for this
system. When combined with new stellar parameters and reanalyzed
transit photometry, our mass measurements place strong constraints on
the compositions of the two small planets. We find that, unlike most
other ultra-short-period planets, the inner planet, WASP-47 e, has a mass
(6.83±0.66 M⊕) and a radius (1.810±0.027 R⊕) that
are inconsistent with an Earth-like composition. Instead, WASP-47 e
likely has a volatile-rich envelope surrounding an Earth-like core and
mantle. We also perform a dynamical analysis to constrain the orbital
inclination of WASP-47 c, the outer Jovian planet. This planet likely
orbits close to the plane of the inner three planets, suggesting a
quiet dynamical history for the system. Our dynamical constraints also
imply that WASP-47 c is much more likely to transit than a geometric
calculation would suggest. We calculate a transit probability for
WASP-47 c of about 10%, more than an order of magnitude larger than
the geometric transit probability of 0.6%.
Description:
We observed WASP-47 with the HARPS-N spectrograph on the 3.58 m
Telescopio Nazionale Galileo (TNG) on the island of La Palma, Spain
(Cosentino et al. 2012SPIE.8446E..1VC). HARPS-N is a stabilized high
resolution (λ/Δλ=115000) optical spectrograph
designed specifically to make precise radial velocity measurements. We
began observing WASP-47 on 2015 July 23, shortly after K2 data revealed
the presence of two small transiting planets (WASP-47 e and WASP-47 d)
in addition to the previously known hot Jupiter (WASP-47 b). We obtained
78 observations of WASP-47 with integration times of 30 minutes. We
measured radial velocities for each exposure by cross-correlating the
HARPS-N spectra with a weighted binary mask (Baranne et al.
1996A&AS..119..373B 1996A&AS..119..373B; Pepe et al. 2002, J/A+A/388/632).
Objects:
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RA (ICRS) DE Designation(s)
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22 04 48.73 -12 01 08.0 WASP-47 = EPIC 206103150
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 26 69 HARPS-N Radial Velocities of WASP-47
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See also:
J/A+A/388/632 : Radial-velocity of HD 108147 and HD 168746 (Pepe+, 2002)
J/A+A/586/A93 : WASP41 and WASP47 photometric and RV data
(Neveu-VanMalle+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d BJD Barycentric Julian Date
13- 21 F9.2 m/s RV [-27219.22/-26870.08] Radial velocity
23- 26 F4.2 m/s e_RV [1.85/7.68] Uncertainty in RV
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 17-Aug-2018