J/AJ/169/234 Planetary & stellar parameters from SED fitting (Jordan+, 2025)
Precise parameters from Bayesian spectral energy distribution fitting indicate
thermally driven mass loss likely driver of radius valley.
Jordan D., Song I.
<Astron. J., 169, 234 (2025)>
=2025AJ....169..234J 2025AJ....169..234J
ADC_Keywords: Exoplanets; Stars, masses; Energy distributions; Models;
Photometry; Optical; Infrared; Ultraviolet
Keywords: Exoplanet formation ; Exoplanet evolution ; Exoplanet systems ;
Stellar properties ; Stellar radii ; Stellar atmospheres ;
Spectral energy distribution ; Bayesian statistics ;
Exoplanet astronomy ; Exoplanet structure ; Planet hosting stars
Abstract:
Several planet formation models have been proposed to explain the gap
in the population of planets between 1.8R⊕ to 2.0R⊕
known as the "radius valley." To apply these models to confirmed
exoplanets, accurate and precise host-star and planet parameters are
required to ensure the observed measurements correctly match model
predictions. Previous studies have emphasized the need for a larger,
more precise sample to further confirm dominant formation processes.
By enhancing standard spectral energy distribution fitting using
Bayesian methods, we derived highly accurate and precise host-star and
planet parameters. Specifically, we achieved median fractional
uncertainties for stellar and planet radii of 2.4% and 3.4%,
respectively. We then produced the largest, most precise sample to
date of 1923 planets when compared to previous studies. This full
sample, as well as a sample filtered for host stellar masses between
0.8 and 1.2M☉, were then used to derive the slope and position
of the radius valley as a function of orbital period, insolation flux,
and stellar mass to compare them to predictive models and previous
observational results. Our results are consistent with thermally
driven mass loss with a planet radius versus orbital period slope of
Rp=P**(-0.142-0.006+0.006) x e**(0.896-0.010+0.012) for the
full sample, leaning toward core-powered mass loss. The planet radius
versus insolation flux slope of
Rp=Sp**(0.136-0.014+0.014)xe**(-0.085-0.030+0.031) for the
filtered sample leaned toward photoevaporation. Also, the slope as a
function of stellar mass for both samples appears more consistent with
thermally driven processes when compared to models and previous
studies.
Description:
To create a large, high-precision sample of planetary radii and
insolation flux to be used in analyzing the radius valley, we start
with the most current exoplanet data from the NASA Exoplanet Archive
site (NASA Exoplanet Science Institute 2024). An original sample of
5638 confirmed exoplanets with planetary and host stellar data was
downloaded from the NASA site on 2024 June 2. Only confirmed planets
were selected.
The original sample was filtered down according to the availability of
other data needed, including transit data to calculate planet radii
Rp and orbital data to calculate insolation flux Sp. In addition,
the radius valley formation analysis is only relevant to orbital
periods between 1 and 100days and planet radii between 1 and 4R⊕.
Finally, to ensure the radius valley slope estimation is as accurate
as possible, only planetary radii with a % fractional uncertainty less
than 5.0% were used, as recommended by Rogers+ (2021MNRAS.508.5886R 2021MNRAS.508.5886R).
The complete filtering resulted in 1434 highly accurate and precise
host-star values that were then used to derive highly accurate and
precise planetary parameters for 1923 exoplanets distributed within
the boundaries of the radius valley.
By using Bayesian-enhanced SED fitting methods, this article focuses
on the creation of the largest planet sample with a much better
precision in planetary radii estimation than previous studies, so as
to allow investigation of the dominant planet formation mechanism
around the radius valley. (SED) fitting techniques with proven stellar
atmosphere models can provide alternative methods for estimating
accurate stellar radii.
The SED fitting process involves comparing the observed SED of a star
with synthetic SEDs generated from theoretical stellar atmospheric
models. The observed input photometric data used in the SED fitting
process comes from many different sources, such as Gaia (DR3, I/355),
Pan-STARRs (DR2, II/389), the Sloan Digital Sky Survey (DR16, V/154),
the Two Micron All-Sky Survey (II/246), the Wide-field Infrared Survey
Explorer (II/311), etc, and covers different wavelengths (e.g.,
ultraviolet, optical, and infrared). There are also several sources of
stellar atmosphere models, such as the NextGen (Hauschildt+,
1999ApJ...512..377H 1999ApJ...512..377H) or CK04 (Castelli+, 2003IAUS..210P.A20C) model
grids.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table4.dat 150 1923 List of the 1923 planets in final sample showing
planetary and stellar parameters
--------------------------------------------------------------------------------
See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/389 : The Pan-STARRS release 1 (PS1) Survey - DR2 (Magnier+, 2025)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
V/154 : Sloan Digital Sky Surveys (SDSS), DR16 (Ahumada+, 2020)
J/ApJS/204/24 : Kepler planetary candidates. III. (Batalha+, 2013)
J/ApJS/211/2 : Revised stellar propert. of Q1-16 Kepler targets (Huber+, 2014)
J/ApJS/217/31 : Kepler planetary candidates. VI. 4yr Q1-Q16 (Mullally+, 2015)
J/MNRAS/452/2127 : Fundamental param. of Kepler stars (Silva Aguirre+, 2015)
J/ApJS/224/12 : Kepler planetary candidates. VII. 48-month (Coughlin+, 2016)
J/MNRAS/465/2634 : Kepler and K2 best candidates for planets (Armstrong+, 2017)
J/AJ/154/109 : California-Kepler Surv. (CKS). III. Planet radii (Fulton+, 2017)
J/AJ/154/107 : California-Kepler Survey (CKS). I. 1305 stars (Petigura+, 2017)
J/ApJS/235/38 : Kepler planetary cand. VIII. DR25 reliability (Thompson+, 2018)
J/AJ/156/264 : California-Kepler Survey. VII. Planet radius gap (Fulton+, 2018)
J/ApJ/875/29 : Spectroscopic analysis of the CKS sample. I. (Martinez+, 2019)
J/AJ/160/108 : Gaia-Kepler stellar properties cat. II. Planets (Berger+, 2020)
J/AJ/159/211 : Exoplanets parameters from Kepler and K2 (Cloutier+, 2020)
J/A+A/640/A25 : Metal-poor stars limb-darkening coeff. (Karovicova+, 2020)
J/ApJ/890/23 : NUV and FUV measurements of planet host stars (Loyd+, 2020)
J/A+A/658/A47 : Dwarf stars limb-darkening coefficients (Karovicova+, 2022)
J/other/Sci/377.1211 : RV and LC of 8 M dwarf stars with planets (Luque+, 2022)
J/AJ/163/179 : The California-Kepler Survey. X. (Petigura+, 2022)
J/MNRAS/513/2719 : Stellar parameters study with SED fit algo (Vines+, 2022)
J/A+A/682/A66 : TOI-732 TESS & CHEOPS detrended light curves (Bonfanti+, 2024)
http://exoplanetarchive.ipac.caltech.edu/index.html : NASA Exoplanet Archive
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- ID Planet identifier
18- 28 F11.8 d Per [1/99.7] Planet orbital period (1)
30- 39 F10.8 d E_Per [0/0.33] Upper uncertainty on Per (1)
41- 51 F11.8 d e_Per [-0.33/0] Lower uncertainty on Per (1)
53- 63 F11.9 Rgeo Rp [1/4] Planet radius in Earth radii (2)
65- 75 F11.9 Rgeo E_Rp [0.02/0.23] Upper uncertainty on Rp (2)
77- 88 F12.9 Rgeo e_Rp [-0.21/-0.02] Lower uncertainty on Rp (2)
90- 104 F15.9 Earth Sp [0.21/10171] Planet insolation flux in Earth units
(3)
106- 118 F13.9 Earth E_Sp [0.007/855.6] Upper uncertainty on Sp (3)
120- 134 F15.9 Earth e_Sp [-1223/-0.007] Lower uncertainty on Sp (3)
136- 139 F4.2 Msun Ms [0.09/1.9] Stellar mass in Sun masses (1)
141- 144 F4.2 Msun E_Ms [0/0.42] Upper uncertainty on Ms (1)
146- 150 F5.2 Msun e_Ms [-0.4/0] Lower uncertainty on Ms (1)
--------------------------------------------------------------------------------
Note (1): Taken directly from NASA Exoplanet Archive on 2024-06-02, 18:41.
Note (2): Calculated using equations 3 and 4. To keep the sample as large and
precise as possible, we chose the method that provided the highest precision
for planet radius once the uncertainties were propagated.
- Equation 3: Rp = 109.27 x Rstar x sqrt(δt) ;
where δt is the transit depth in ratio of star brightness blocked by
the transiting planet, and the constant 109.27 is the ratio of the Sun's
radius to the Earth's radius.
- Equation 4: Rp = 109.27 x (Rp / Rstar)NASA ;
which is another way to calculate planet radius is by using the ratio of
planet to star radius as provided by the NASA Exoplanet archive.
Note (3): Calculated using equations 5 and 6 or taken directly from
the NASA Exoplanet Archive on 2024-06-02, 18:41. To keep the sample as large
and precise as possible, we chose the method that provided the highest
precision for insolation flux once uncertainties were propagated.
- Equation 5: (Sp / S⊕) = (L* / L☉) x (AU / a)2 ;
where Sp is in terms of Earth's value, L* is in terms of its solar
value, and the semimajor axis a is in AU from the NASA Exoplanet Archive.
- Equation 6: a = (P2 x G x M* / (4π2))1/3 ;
where P is the orbital period, G is the gravitational constant, and M* is
the mass of the host star.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 20-Jan-2026