J/MNRAS/539/307 Eccentricity distribution of giant planets (Alqasim+, 2025)
Investigating the eccentricity distribution of transiting,
long-period giant planets.
Alqasim A., Hirano T., Hori Y., Kawata D., Livingston J., Howell S.B.,
Lanza A.F., Mann A.W., Ziegler C., Briceno C., Beichman C.A., Ciardi D.R.,
Strakhov I.A., Lund M.B., Law N.
<Mon. Not. R. Astron. Soc. 539, 307-329 (2025)>
=2025MNRAS.539..307A 2025MNRAS.539..307A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Stars, ages ;
Abundances, [Fe/H] ; Stars, masses ; Stars, diameters ;
Combined data
Keywords: methods: statistical - planets and satellites: gaseous planets -
planet-star interactions - stars: fundamental parameters
Abstract:
Eccentric giant planets are predicted to have acquired their
eccentricity through two major mechanisms: the Kozai-Lidov effect or
planet-planet scattering, but it is normally difficult to separate the
two mechanisms and determine the true eccentricity origin for a given
system. In this work, we focus on a sample of 92 transiting,
long-period giant planets (TLGs) as part of an eccentricity
distribution study for this planet population in order to understand
their eccentricity origin. Using archival high-contrast imaging
observations, public stellar catalogs, precise Gaia astrometry, and
the NASA Exoplanet Archive database, we explored the eccentricity
distribution correlation with different planet and host-star
properties of our sample. We also homogeneously characterized the
basic stellar properties for all 86 host-stars in our sample,
including stellar age and metallicity. We found a correlation between
eccentricity and stellar metallicity, where lower-metallicity stars
([Fe/H]≤0.1) did not host any planets beyond e>0.4, while
higher-metallicity stars hosted planets across the entire eccentricity
range. Interestingly, we found no correlation between the eccentricity
distribution and the presence of stellar companions, indicating that
planet-planet scattering is likely a more dominant mechanism than the
Kozai-Lidov effect for TLGs. This is further supported by an
anti-correlation trend found between planet multiplicity and
eccentricity, as well as a lack of strong tidal dissipation effects
for planets in our sample, which favor planet-planet scattering
scenarios for the eccentricity origin.
Description:
We present a population study on a statistical level for the observed
eccentricity distribution of transiting, long-period giant planets
(TLGs). We homogeneously characterized the basic stellar properties
for all host-stars in our sample. We used archival high-contrast
imaging observations, public stellar catalogs, precise Gaia
astrometry, and the NASA Exoplanet Archive database, to explore the
eccentricity distribution correlation with different planet and
host-star properties.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
nexa_pl.dat 92 92 Planet parameters of our sample,
extracted from the NASA Exoplanet Archive
nexa_st.dat 73 86 Stellar parameters of our sample,
extracted from the NASA Exoplanet Archive
jaxstar.dat 72 86 Stellar parameters of our sample, homogenously
derived using jaxstar
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Byte-by-byte Description of file: nexa_pl.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [TIC]
5- 13 I9 --- TIC Name of the star as given by the
TESS Input Catalog (TIC) (tic_id)
15- 30 A16 --- Planet Planet name most commonly used in the
literature (pl_name)
32- 41 F10.6 d PerPl Planet period (period)
43- 50 F8.6 d e_PerPl Planet period error (period_err)
52- 56 F5.2 Rgeo RadPl Planet radius (in Earth radius units)
(r_earth)
58- 61 F4.2 Rgeo e_RadPl Planet radius error (in Earth radius units)
(reartherr)
63- 69 F7.2 Mgeo MassPl Planet mass (in Earth mass units) (m_earth)
71- 76 F6.2 Mgeo e_MassPl Planet mass error (in Earth mass units)
(meartherr)
78- 83 F6.4 --- eccPl Planet eccentricity (ecc)
85- 90 F6.4 --- e_eccPl Planet eccentricity error (ecc_err)
92 I1 --- Npl Number of confirmed planets in the planetary
system (num_planets)
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Byte-by-byte Description of file: nexa_st.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [TIC]
5- 13 I9 --- TIC Name of the star as given by the
TESS Input Catalog (TIC) (tic_id)
15- 28 A14 --- Hostname Host star name most commonly used in the
literature (hostname)
30- 34 A5 Gyr Age Host star age (nexa_age)
36- 40 A5 Gyr e_Age Host star age error (nexaageerr)
42- 47 F6.3 --- [Fe/H] Host star metallicity [Fe/H] (metallicity)
49- 53 F5.3 --- e_[Fe/H] Host star metallicity [Fe/H] error
(metallicity_err)
55- 58 I4 K Teff Host star effective temperature (teff_star)
60- 62 I3 K e_Teff Host star effective temperature error
(teffstarerr)
64- 68 F5.2 mag Kmag Brightness of the host star as measured using
the K (2MASS) band (Kmag)
70- 73 F4.2 mag e_Kmag Error of the brightness of the host star as
measured using the K (2MASS) band (Kmag_err)
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Byte-by-byte Description of file: jaxstar.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [TIC]
5- 13 I9 --- TIC Name of the star as given by the TESS Input
Catalog (TIC) (tic_id)
15- 19 F5.2 Gyr Age Host star age (jaxstar_age)
21- 24 F4.2 Gyr e_Age Host star age error (jaxstarageerr)
26- 32 F7.4 --- [Fe/H] Host star metallicity [Fe/H] (jaxstar_feh)
34- 39 F6.4 --- e_[Fe/H] Host star metallicity [Fe/H] error
(jaxstarfeherr)
41- 45 F5.3 Msun Mass Host star mass (jaxstar_mass)
47- 51 F5.3 Msun e_Mass Host star mass error (jaxstarmasserr)
53- 57 F5.3 Rsun Rad Host star radius (jaxstar_radius)
59- 63 F5.3 Rsun e_Rad Host star radius error (jaxstarradiuserr)
65- 68 I4 K Teff Host star effective temperature (jaxstar_teff)
70- 72 I3 K e_Teff Host star effective temperature error
(jaxstartefferr)
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Acknowledgements:
Ahlam Alqasim, ahlam.alqasim.17(at)ucl.ac.uk
(End) Patricia Vannier [CDS] 11-Mar-2025