J/ApJ/772/80 Radial velocities of HAT-P-17 (Fulton+, 2013)
The stellar obliquity and the long-period planet in the HAT-P-17 exoplanetary
system.
Fulton B.J., Howard A.W., Winn J.N., Albrecht S., Marcy G.W., Crepp J.R.,
Bakos G.A., Johnson J.A., Hartman J.D., Isaacson H., Knutson H.A., Zhao M.
<Astrophys. J., 772, 80 (2013)>
=2013ApJ...772...80F 2013ApJ...772...80F
ADC_Keywords: Radial velocities ; Stars, double and multiple ; Planets
Keywords: planets and satellites: fundamental parameters;
planets and satellites: individual: HAT-P-17b;
techniques: high angular resolution; techniques: radial velocities
Abstract:
We present the measured projected obliquity -the sky-projected angle
between the stellar spin axis and orbital angular momentum- of the
inner planet of the HAT-P-17 multi-planet system. We measure the
sky-projected obliquity of the star to be λ=19-16+14deg by
modeling the Rossiter-McLaughlin effect in Keck/HIRES radial
velocities (RVs). The anomalous RV time series shows an asymmetry
relative to the midtransit time, ordinarily suggesting a nonzero
obliquity -but in this case at least part of the asymmetry may be due
to the convective blueshift, increasing the uncertainty in the
determination of λ. We employ the semi-analytical approach of
Hirano et al. (2011ApJ...742...69H 2011ApJ...742...69H) that includes the effects of
macroturbulence, instrumental broadening, and convective blueshift to
accurately model the anomaly in the net RV caused by the planet
eclipsing part of the rotating star. Obliquity measurements are an
important tool for testing theories of planet formation and migration.
To date, the measured obliquities of ∼50 Jovian planets span the full
range, from prograde to retrograde, with planets orbiting cool stars
preferentially showing alignment of stellar spins and planetary
orbits. Our results are consistent with this pattern emerging from
tidal interactions in the convective envelopes of cool stars and
close-in planets. In addition, our 1.8yr of new RVs for this system
show that the orbit of the outer planet is more poorly constrained
than previously thought, with an orbital period now in the range of
10-36yr.
Description:
Since the publication of Howard+, 2012 (H12; Cat. J/ApJ/749/134), we
have measured the radial velocities (RV) of HAT-P-17 (V=10.54) for an
additional 1.8yr using HIRES on the Keck I telescope.
The complete set of RV measurements and their uncertainties are listed
in Table 1. These 100 RVs include 42 RVs from H12, 45 new RVs taken on
the night of UT 2012 August 26 to measure the RM effect, and 13
additional RVs taken sporadically between 2010 April and 2012 December
to measure the orbit of HAT-P-17c.
In order to search for additional companions and sources of possible
photometric dilution, we obtained high spatial resolution images of
HAT-P-17 using NIRC2 at the Keck II telescope on 2012-05-07 UT.
Objects:
----------------------------------------------------------------------
RA (ICRS) DE Designation(s) (Period)
----------------------------------------------------------------------
21 38 08.73 +30 29 19.4 HAT-P-17 = TYC 2717-417-1 (P=10.338523)
----------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 27 100 Radial velocity data
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See also:
J/A+A/556/A150 : SWEETCat I. Stellar parameters for host stars (Santos+, 2013)
J/ApJ/757/161 : Spectroscopy of 56 exoplanet host stars (Torres+, 2012)
J/ApJ/757/18 : RVs for 16 hot Jupiter host stars (Albrecht+, 2012)
J/ApJ/750/114 : Kepler TTVs. IV. 4 multiple-planet systems (Fabrycky+, 2012)
J/ApJ/749/134 : HAT-P-17 radial velocities and light curves (Howard+, 2012)
J/ApJ/703/L99 : Outlandish orbit of HAT-P-7b (Winn+, 2009)
J/ApJS/159/141 : Spectroscopic properties of cool stars. I. (Valenti+, 2005)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d BJD Barycentric Julian Date in Barycentric
Dynamical Time (BJD-2440000)
14- 21 F8.3 m/s RVel [-129/71] Radial velocity
23- 27 F5.3 m/s e_RVel [1/3] The 1σ error in RVel
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 03-Feb-2015