J/AJ/161/157 10 years radial-velocity monitoring of Vega with TRES (Hurt+, 2021)
A decade of radial-velocity monitoring of Vega and new limits on the presence of
planets.
Hurt S.A., Quinn S.N., Latham D.W., Vanderburg A., Esquerdo G.A.,
Calkins M.L., Berlind P., Angus R., Latham C.A., Zhou G.
<Astron. J., 161, 157 (2021)>
=2021AJ....161..157H 2021AJ....161..157H
ADC_Keywords: Exoplanets; Stars, A-type; Radial velocities; Spectra, optical
Keywords: Exoplanet astronomy ; Exoplanet detection methods ; Exoplanets ;
Stellar activity ; Stellar magnetic fields ; Photometry ;
Radial velocity ; Circumstellar disks
Abstract:
We present an analysis of 1524 spectra of Vega spanning 10yr, in which
we search for periodic radial-velocity variations. A signal with a
periodicity of 0.676day and a semi-amplitude of ∼10m/s is consistent
with the rotation period measured over much shorter time spans by
previous spectroscopic and spectropolarimetric studies, confirming the
presence of surface features on this A0 star. The activity signal
appears to evolve on long timescales, which may indicate the presence
of failed fossil magnetic fields on Vega. TESS data reveal Vega's
photometric rotational modulation for the first time, with a total
amplitude of only 10ppm. A comparison of the spectroscopic and
photometric amplitudes suggests that the surface features may be
dominated by bright plages rather than dark spots. For the shortest
orbital periods, transit and radial-velocity injection recovery tests
exclude the presence of transiting planets larger than 2R⊕ and
most non- transiting giant planets. At long periods, we combine our
radial velocities with direct imaging from the literature to produce
detection limits for Vegan planets and brown dwarfs out to distances
of 15au. Finally, we detect a candidate radial-velocity signal with a
period of 2.43days and a semi-amplitude of 6m/s. If caused by an
orbiting companion, its minimum mass would be ∼20M⊕; because of
Vega's pole-on orientation, this would correspond to a Jovian planet
if the orbit is aligned with the stellar spin. We discuss the
prospects for confirmation of this candidate planet.
Description:
We obtained high-resolution spectra of Vega with the Tillinghast
Reflector Echelle Spectrograph (TRES), which is mounted on the 1.5m
Tillinghast Reflector at Fred L.Whipple Observatory on Mount Hopkins,
AZ. It has a resolving power of R∼44000, and a wavelength coverage of
3850-9100Å. We obtained a total of 1524 spectra spanning the
ten-year period between UT 2009 June 13 and 2019 October 24. Typical
exposure times ranged from a few seconds to a few tens of seconds,
achieving signal-to-noise ratios (S/Ns) between about 300 and 1000 per
resolution element.
Objects:
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RA (2000) DE Designation(s) (Period)
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18 36 56.336 +38 47 01.280 Vega = Vega (P=0.71d)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 32 1524 TRES Radial Velocities of Vega
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See also:
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
J/AJ/124/1144 : Orbits of 171 single-lined spectro. binaries (Latham, 2002)
J/PASP/122/162 : Direct imaging of exoplanets (Beichman+, 2010)
J/ApJ/720/1118 : i-band photometry of HAT-P-16 (Buchhave+, 2010)
J/A+A/531/L2 : Images of Vega at 1.3mm (Pietu+, 2011)
J/ApJ/757/18 : RVel for 16 hot Jupiter host stars (Albrecht+, 2012)
J/other/Sci/350.64 : 51 Eri b near-infrared spectrum (Macintosh+, 2015)
J/AJ/152/136 : Follow-up photometry and spectroscopy of KELT-17 (Zhou+, 2016)
J/MNRAS/474/2094 : Inferring proba. stellar rotation periods (Angus+, 2018)
J/A+A/618/A20 : Limb-darkening for TESS, Kepler, Corot, MOST (Claret, 2018)
J/ApJ/860/109 : Keck HIRES obs. 245 subgiants (retired Astars) (Ghezzi+, 2018)
J/A+A/632/A69 : CaII transmission spectrum of WASP-33b and KELT-9b (Yan+,2019)
J/AJ/158/141 : Differential photo. & RVs of HAT-P-69 & HAT-P-70 (Zhou+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [0/1523] Internal index number
6- 19 F14.6 d BJD [2454995/2458928] Barycentric Julian Date
21- 26 F6.1 m/s RVel [-162/118] Radial velocity
28- 32 F5.1 m/s e_RVel [10.5/144] Uncertainty in RVel
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 21-Jun-2021