J/A+A/524/A25 Radial Velocities on 6 exoplanet host stars (Triaud+, 2010)
Spin-Orbit angle measurements for six southern transiting planets;
New insights into the dynamical origins of hot Jupiters.
Triaud A.H.M.J., Collier C.A., Queloz D., Anderson D.R., Gillon M.,
Hebb L., Hellier C., Loeillet B., Maxted P.F., Mayor M., Pepe F.,
Pollacco D., Segransan D., Smalley B., Udry S., West R.G., Wheatley P.J.
<Astron. Astrophys. 524, A25 (2010)>
=2010A&A...524A..25T 2010A&A...524A..25T
ADC_Keywords: Planets ; Radial velocities
Keywords: binaries: eclipsing - stars: general - techniques: spectroscopic
Abstract:
For transiting planets, the Rossiter-McLaughlin effect allows the
measurement of the sky-projected angle beta between the stellar
rotation axis and a planet's orbital axis. Using the HARPS
spectrograph, we observed the Rossiter-McLaughlin effect for six
transiting hot Jupiters found by the WASP consortium. We combine these
with long term radial velocity measurements obtained with CORALIE. We
found that three of our targets have a projected spin-orbit angle
above 90 degrees: WASP-2b: beta=153+11-15°,
WASP-15b: beta=139.6+5.2-4.3° and
WASP-17b: beta=148.5+5.1-4.2° ; the other three (WASP-4b,
WASP-5b and WASP-18b) have angles compatible with 0 degrees. There
is no dependence between the misaligned angle and planet mass nor
with any other planetary parameter. All orbits are close to
circular, with only one firm detection of eccentricity on WASP-18b
with e=0.00848+0.00085-0.00095. No long term radial acceleration
was detected for any of the targets. Combining all previous 20
measurements of beta and our six, we attempt to statistically
determine the distribution of the real spin-orbit angle psi and find
that between about 45 and 85% of hot Jupiters have psi>30°.
Observations and predictions using the Kozai mechanism match well.
If these observational facts are confirmed in the future, we may then
conclude that most hot Jupiters are formed from a dynamical and tidal
origin without the necessity to use type I or II migration. At
present, standard disc migration cannot explain the observations
without invoking at least another additional process.
Description:
Radial velocities from 6 exoplanet host stars. The velocities are
extracted from the CORALIE and HARPS spectrographs by means of a
cross-correlation and the subsequent fit of a Gaussian on the
resulting mean absorption line.
Objects:
----------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------
20 30 54.1 +06 25 46 WASP-2b = WASP-2b
23 34 15.0 -42 03 41 WASP-4b = WASP-4b
23 57 23.8 -41 16 38 WASP-5b = WASP-5b
13 55 42.7 -32 09 35 WASP-15b = WASP-15b
15 59 50.9 -28 03 42 WASP-17b = WASP-17b
01 37 25.0 -45 40 40 WASP-18b = HD 10069b
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
planets.dat 33 6 Orbital parameters (from table3)
rvdata.dat 56 442 *The Radial-Velocity data extracted by fitting a
Gaussian function on a Cross-Correlation
Function resulting from comparing the spectra
with a mask corresponding to its spectral type
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Note on rvdata.dat: The data is presented per instrument and separated in
various datasets: overall Doppler shift and Rossiter-McLaughlin effect, as
was done for the fits. Within each dataset, it is presented chronologically.
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See also:
J/A+A/508/1509 : Sky maps for hot Jupiters (Heller+, 2009)
J/A+A/513/L8 : BD+20 1790 radial velocity curve (Figueira+, 2010)
Byte-by-byte Description of file: planets.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Planet name
10- 18 F9.7 d P Orbital period
21- 26 F6.4 AU a Semi-major axis of orbit
28- 33 F6.3 jovMass Mp Mass of planet, in Jovian masses
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Byte-by-byte Description of file: rvdata.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Planet name
10- 11 A2 --- Inst Instrument used (1)
13- 26 F14.6 d BJD Calculated Barycentric Julian Date at mid
exposure (weighted in time according to flux)
30- 38 F9.5 km/s RV Estimated Radial Velocity of the star at
Solar system barycentre
42- 48 F7.5 km/s e_RV Estimated 1 sigma error bar on RV
53- 56 I4 s Exp Time of exposure
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Note (1): Instruments as follows:
S1 = SOPHIE, orbital Doppler shift
C1 = CORALIE, orbital Doppler shift
C2 = CORALIE, Rossiter-McLaughlin effect
H1 = HARPS, orbital Doppler shift
H2 = HARPS, Rossiter-McLaughlin effect
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Acknowledgements:
Amaury Triaud (Obs. de Geneve), Amaury.Triaud(at)unige.ch
(End) Patricia Vannier [CDS] 16-Aug-2010