Key parameters at a glance

A radius of 2.11 Earth radii
A mass of 8.32 Earth masses
Surface gravity around 1.87 g
An orbital period of 3.295 days
Semi-major axis 0.0370 AU
Equilibrium temperature 695 K (422 °C)
Distance from Earth 230.64 light-years
Earth Similarity Index 0.409
Travel time at Voyager 1 speed 4,067,329 years
Almost certainly tidally locked to its host star given the close orbit

1 sibling around TOI-1238

TOI-1238 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
TOI-1238 b	Rocky Terrestrial	1.21	3.76	0.765	1,133	2022
TOI-1238 c this	Sub-Neptune	2.11	8.32	3.295	695	2022

TOI-1238 c Planet Profile

Physical Specs

Radius

2.11 R⊕

Radius (Jupiter)

0.188 R♃

Mass

8.32 M⊕

Mass (Jupiter)

0.026 M♃

Density

4.90 g/cm³

Surface Gravity

1.87 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.409

HZ Position Inner

Controversial No

Discovery

Year 2022

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#1806of 1978

top 91.3%

This planet

2.11R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

61 Vir b 2.11 R⊕ Kepler-1484 b 2.11 R⊕ Kepler-518 b 2.11 R⊕

Metric	Earth	TOI-1238 c	Jupiter
Radius (R⊕)	1.00	2.11	11.21
Mass (M⊕)	1.00	8.32	317.83
Density (g/cm³)	5.51	4.90	1.33
Surface Gravity (g)	1.00	1.87	2.53
Insolation (S⊕)	1.00	63.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	8.320 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	8.320 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

TIC

TIC 153951307

Gaia DR2

Gaia DR2 1685195530290375168

Gaia DR3

Gaia DR3 1685195530290375168

System

TOI-1238

Percentile among Sub-Neptune cohort

Radius 2.110 R⊕ · percentile 8 / cohort 1978

Mass 8.320 M⊕ · percentile 58 / cohort 1978

Orbital period 3.29 d · percentile 6 / cohort 1946

Distance 70.71 pc · percentile 16 / cohort 1975

ESI 0.409 · percentile 54 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

3.295 days

Semi-major axis

0.0370 AU

Eccentricity

0.150

Inclination

88.38 °

Year Length

A year here lasts approximately 3.29 Earth days (0.9% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0370 AU.

Transit Fingerprint

Depth

0.111 %

Duration

1.750 h

Impact parameter b

0.390

Rp / R★

0.033000

Transit midpoint (BJD)

2,458,707.3520

Photometric dip

Transit produces a flux drop of 1,113 ppm lasting ≈ 1.75 h.

Extended Orbital Architecture

Planet / star radius ratio

0.033000

Semi-major axis / stellar radius

13.730

Impact parameter (b)

0.390

RV semi-amplitude (K)

5.100 m/s

Transit mid-time (BJD)

2,458,707.3520

Angular separation (arcsec)

0.52300

Eq. Temperature

695K

(422 °C)

Insolation (S⊕)

63.00

Earth = 1.00

Earth Similarity (ESI)

0.409

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Gonzalez Alvarez et al. 2022

Instrument

TESS CCD Array

Publication

2022-02

Observation locale

Space

Discovery cohort

Planets confirmed in 2022 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-1452 b · Super-Earth TOI-712 d · Sub-Neptune TOI-1468 c · Sub-Neptune TOI-2136 b · Sub-Neptune LTT 1445 A c · Rocky Terrestrial TOI-712 c · Sub-Neptune LP 890-9 b · Super-Earth TOI-2081 b · Sub-Neptune GJ 3929 b · Rocky Terrestrial HD 260655 c · Super-Earth HD 73583 c · Sub-Neptune TOI-1759 b · Sub-Neptune

Host System: TOI-1238

Spectral Class

K-type orange

Effective Temperature

4,089 K — cooler than the Sun (5,778 K)

Estimated Age

0.80 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.580 R☉

Stellar Mass

0.590 M☉

Metallicity [Fe/H]

0.31

Extended Stellar Properties

Surface gravity (log g)

4.630 dex

Stellar density

4.511 g/cm³

Systemic radial velocity

-17.49 km/s

Rotational v·sin i

2.00 km/s

Rotation period

40.00 days

Metallicity ratio

[Fe/H]

Distance

70.71 parsec

Light-years 230.64 ly

V-band magnitude

12.80 mag

Voyager-speed travel 4,067,329 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

14.112 mas

Total Proper Motion

46.189 mas/yr

PM Right Ascension

-4.96 mas/yr

PM Declination

-45.92 mas/yr

Galactic Cartesian (pc)

x = -0.336 · y = -0.132 · z = 0.933

Equatorial (J2000)

RA 201.38234° · Dec 68.83607°

Galactic ℓ, b

118.346° · 47.988°

Ecliptic λ, β

143.341° · 65.225°

HTM-20 index

-86854967

Similar Worlds

Kepler-705 b

Sub-Neptune · K-type orange

Radius 2.11 R⊕ · 903.1 ly

K2-345 b

Sub-Neptune · K-type orange

Radius 2.11 R⊕ · 529.7 ly

Kepler-1880 b

Sub-Neptune · K-type orange

Radius 2.12 R⊕ · 1,992.9 ly

Kepler-1895 b

Sub-Neptune · K-type orange

Radius 2.12 R⊕ · 3,210.0 ly

Kepler-161 b

Sub-Neptune · K-type orange

Radius 2.12 R⊕ · 1,417.6 ly

HD 39194 d

Sub-Neptune · K-type orange

Radius 2.12 R⊕ · 86.1 ly

Explore Related Categories

Sub-Neptune Planets Transit Discoveries Transiting Exoplanet Survey Satellite (TESS) Mission K-type orange Hosts