J/AJ/161/68 Obliquities of 150 hot Kepler hosting stars (Louden+, 2021)
Hot stars with Kepler planets have high obliquities.
Louden E.M., Winn J.N., Petigura E.A., Isaacson H., Howard A.W., Masuda K.,
Albrecht S., Kosiarek M.R.
<Astron. J., 161, 68 (2021)>
=2021AJ....161...68L 2021AJ....161...68L
ADC_Keywords: Stars, G-type; Stars, F-type; Exoplanets; Abundances, [Fe/H];
Effective temperatures; Rotational velocities; Optical
Keywords: Exoplanets ; Stellar rotation
Abstract:
It has been known for a decade that hot stars with hot Jupiters tend
to have high obliquities. Less is known about the degree of spin-orbit
alignment for hot stars with other kinds of planets. Here, we reassess
the obliquities of hot Kepler stars with transiting planets smaller
than Neptune, based on spectroscopic measurements of their projected
rotation velocities (vsini). The basis of the method is that a lower
obliquity-all other things being equal-causes sini to be closer to
unity and increases the value of vsini. We sought evidence for this
effect using a sample of 150 Kepler stars with effective temperatures
between 5950 and 6550K and a control sample of 101 stars with matching
spectroscopic properties and random orientations. The planet hosts
have systematically higher values of vsini than the control stars, but
not by enough to be compatible with perfect spin-orbit alignment. The
mean value of sini is 0.856±0.036, which is 4σ away from
unity (perfect alignment), and 2σ away from π/4 (random
orientations). There is also evidence that the hottest stars have a
broader obliquity distribution: when modeled separately, the stars
cooler than 6250K have <sini≤0.928±0.042 while the hotter stars
are consistent with random orientations. This is similar to the
pattern previously noted for stars with hot Jupiters. Based on these
results, obliquity excitation for early-G and late-F stars appears to
be a general outcome of star and planet formation, rather than being
exclusively linked to hot Jupiter formation.
Description:
We drew the data for the planet hosts from the California-Kepler
Survey (CKS; Petigura+, 2017, J/AJ/154/107 and
Johnson+, 2017, J/AJ/154/108). The CKS team performed Keck/High
Resolution Echelle Spectrometer (HIRES) spectroscopy of 1305 stars
with transiting planets, of which several hundred have spectral types
in the desired range. They provided precise determinations of the
effective temperature, surface gravity, iron metallicity, and
projected rotation velocity.The uncertainties in Teff, logg, [Fe/H],
and vsini are 60K, 0.1, 0.1, and 1km/s, respectively.
Our sample contains 150 planet hosts and 101 control stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 35 150 Spectroscopic properties of the planet hosts
table2.dat 30 101 Spectroscopic properties of the control stars
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See also:
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/ApJ/801/3 : Rotation periods for Q3-Q14 KOIs (Mazeh+, 2015)
J/AJ/154/108 : California-Kepler Survey (CKS). II. Properties (Johnson+, 2017)
J/AJ/154/107 : California-Kepler Survey (CKS). I. 1305 stars (Petigura+, 2017)
J/AJ/156/264 : California-Kepler Survey. VII. Planet radius gap (Fulton+,2018)
J/ApJS/235/38 : Kepler planetary cand. VIII. DR25 reliability (Thompson+, 2018)
J/A+A/635/A43 : Stellar Prot from K2 Campaigns 0-18 (Reinhold+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Kepler Input Catalog identifier
10- 13 I4 --- KOI Kepler Object of Interest identifier
15- 18 I4 K Teff [5950/6540] Effective temperature
20- 23 F4.2 --- logg [3.95/4.45] Surface gravity
25- 29 F5.2 --- [Fe/H] [-0.29/0.3] Metallicity
31- 35 F5.2 km/s vsini [2.31/18.56] Rotational velocity
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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- 8 I8 --- KIC Kepler Input Catalog identifier
10- 13 I4 K Teff [5951/6536] Effective temperature
15- 18 F4.2 --- logg [3.96/4.44] Surface gravity
20- 24 F5.2 --- [Fe/H] [-0.29/0.27] Metallicity
26- 30 F5.2 km/s vsini [1.71/18.22] Rotational velocity
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History:
From electronic version of the journal
(End) Prepared by Coralie Fix [CDS], 04-May-2021