Key parameters at a glance

A radius of 1.21 Earth radii
A mass of 3.76 Earth masses
Surface gravity around 2.57 g
An orbital period of 0.765 days
Semi-major axis 0.0139 AU
Equilibrium temperature 1,133 K (860 °C)
Distance from Earth 230.64 light-years
Earth Similarity Index 0.235
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 b 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 this	Rocky Terrestrial	1.21	3.76	0.765	1,133	2022
TOI-1238 c	Sub-Neptune	2.11	8.32	3.295	695	2022

TOI-1238 b Planet Profile

Physical Specs

Radius

1.21 R⊕

Radius (Jupiter)

0.108 R♃

Mass

3.76 M⊕

Mass (Jupiter)

0.012 M♃

Density

11.70 g/cm³

Surface Gravity

2.57 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.235

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

#56of 570

top 9.6%

This planet

1.21R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-415 b 1.21 R⊕ Kepler-169 c 1.21 R⊕ Kepler-189 b 1.21 R⊕

Metric	Earth	TOI-1238 b	Jupiter
Radius (R⊕)	1.00	1.21	11.21
Mass (M⊕)	1.00	3.76	317.83
Density (g/cm³)	5.51	11.70	1.33
Surface Gravity (g)	1.00	2.57	2.53
Insolation (S⊕)	1.00	442.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	3.760 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	3.750 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 Rocky Terrestrial cohort

Radius 1.210 R⊕ · percentile 87 / cohort 570

Mass 3.760 M⊕ · percentile 94 / cohort 570

Orbital period 0.76 d · percentile 7 / cohort 567

Distance 70.71 pc · percentile 21 / cohort 566

ESI 0.235 · percentile 22 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

0.765 days

Semi-major axis

0.0139 AU

Eccentricity

0.250

Inclination

86.51 °

Year Length

A year here lasts roughly 18.4 hours long on a mildly elliptical path at a mean orbital distance of 0.0139 AU.

Transit Fingerprint

Depth

0.037 %

Duration

1.090 h

Impact parameter b

0.320

Rp / R★

0.019000

Transit midpoint (BJD)

2,458,684.1020

Photometric dip

Transit produces a flux drop of 366 ppm lasting ≈ 1.09 h.

Extended Orbital Architecture

Planet / star radius ratio

0.019000

Semi-major axis / stellar radius

5.190

Impact parameter (b)

0.320

RV semi-amplitude (K)

3.740 m/s

Transit mid-time (BJD)

2,458,684.1020

Angular separation (arcsec)

0.19700

Eq. Temperature

1,133K

(860 °C)

Insolation (S⊕)

442.00

Earth = 1.00

Earth Similarity (ESI)

0.235

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched. 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