J/ApJ/890/L31 Rotational periods and J2 of Kepler stars (Li+, 2020)
Mutual inclination excitation by stellar oblateness.
Li G., Dai F., Becker J.
<Astrophys. J., 890, L31 (2020)>
=2020ApJ...890L..31L 2020ApJ...890L..31L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple; Exoplanets; Stars, diameters
Keywords: Exoplanet systems; Exoplanet dynamics
Abstract:
Ultra-short-period planets (USPs) provide important clues to planetary
formation and migration. It was recently found that the mutual
inclinations of the planetary systems are larger if the inner orbits
are closer (≲5R*) and if the planetary period ratios are larger
(P2/P1≳5). This suggests that the USPs experienced both
inclination excitation and orbital shrinkage. Here we investigate the
increase in the mutual inclination due to stellar oblateness. We find
that the stellar oblateness (within ∼1Gyr) is sufficient to enhance
the mutual inclination to explain the observed signatures. This
suggests that the USPs can migrate closer to the host star in a near
coplanar configuration with their planetary companions (e.g., disk
migration+tides or in situ+tides), before mutual inclination gets
excited due to stellar oblateness.
Description:
We measured the stellar rotation periods of the stars in our sample
using the quasi-sinusoidal flux variations in the Kepler light curves.
We used both autocorrelation function (McQuillan+ 2013, J/ApJ/775/L11)
and Lomb-Scargle periodogram (Lomb 1976Ap&SS..39..447L 1976Ap&SS..39..447L and
Scargle+ 2013ApJ...764..167S 2013ApJ...764..167S). We considered a rotation period a solid
detection when the autocorrelation function and the periodogram gave
consistent results. We also compared our results with
McQuillan+ (2013, J/ApJ/775/L11) and Angus+ (2018, J/MNRAS/474/2094).
The results are presented in Table 1.
To estimate the J2 of the star, we need the stellar masses and radii.
We cross-matched our star list with the California-Kepler Survey (see
Fulton+, 2018, J/AJ/156/264). If no match was found, we adopted the
stellar parameters reported by Mathur+ (2017, J/ApJS/229/30).
See Section 3.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 96 80 Planetary system properties
--------------------------------------------------------------------------------
See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
J/A+A/497/497 : Physical parameters from JHK flux (Gonzalez-Hernandez+, 2009)
J/ApJ/700/302 : Relative photometry of XO-3 (Winn+, 2009)
J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)
J/ApJ/775/L11 : Stellar rotation periods for KOIs (McQuillan+, 2013)
J/ApJ/784/45 : Kepler's multiple planet candidates. III. (Rowe+, 2014)
J/ApJ/787/47 : 106 Kepler ultra-short-period planets (Sanchis-Ojeda+, 2014)
J/ApJ/822/86 : False positive prob. for Q1-Q17 DR24 KOIs (Morton+, 2016)
J/ApJ/834/17 : Mass & radius of planets, moons, low mass stars (Chen+, 2017)
J/ApJ/839/92 : Praesepe members with K2 light curve data (Rebull+, 2017)
J/ApJS/229/30 : Revised properties of Q1-17 Kepler targets (Mathur+, 2017)
J/AJ/156/264 : California-Kepler Survey. VII. Planet rad. gap (Fulton+, 2018)
J/MNRAS/474/2094 : Inferring probabilistic stellar rot. periods (Angus+, 2018)
J/ApJ/879/49 : Rotation periods for Gaia members of NGC 6811 (Curtis+, 2019)
J/ApJ/879/100 : K2 rot. periods for Hyades & Praesepe members (Douglas+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Object identifier
16- 20 F5.2 --- a/R* [2/17.7] Innermost planetary semi-major axis
to stellar radius ratio
22- 25 F4.2 --- E_a/R* [0.02/0.7] Upper uncertainty in a/R*
27- 30 F4.2 --- e_a/R* [0.02/0.7] Lower uncertainty in a/R*
32- 36 F5.2 deg deltai [0.2/11.3] Planetary mutual inclination
38- 41 F4.2 deg E_deltai [0.13/4.6] Upper uncertainty in deltai
43- 46 F4.2 deg e_deltai [0.13/7.3] Lower uncertainty in deltai
48- 52 F5.2 d Prot [5.3/42] Stellar rotation period
54- 57 F4.2 d E_Prot [0.1/6.5] Upper uncertainty in Prot
59- 63 F5.2 d e_Prot [0.1/22.1] Lower uncertainty in Prot
65- 71 E7.2 --- J2t [7.6e-9/6.2e-6] Current day J2 value (1)
73- 80 E8.2 --- E_J2t [3.5e-10/9.9e-6] Upper uncertainty in J2t
82- 88 E7.2 --- e_J2t [3.5e-10/1.2e-6] Lower uncertainty in J2t
90- 96 E7.2 --- J2req [1.7e-8/0.08] Minimum J2 value required
--------------------------------------------------------------------------------
Note (1): To estimate the J2 of the stars in our sample we use the Equations
below (e.g., Sterne 1939MNRAS..99..451S 1939MNRAS..99..451S and
Spalding & Batygin 2016ApJ...830....5S 2016ApJ...830....5S):
J2=1/3(Ω/Ωb)2k2 (Equation (2))
where Ω is the stellar rotational frequency; Ωb is the
rotational frequency at break-up; k2 is the love number.
See Section 3.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Aug-2021