Key parameters at a glance

A radius of 2.92 Earth radii
A mass of 7.39 Earth masses
Surface gravity around 0.87 g
An orbital period of 25.503 days
Semi-major axis 0.1632 AU
Equilibrium temperature 744 K (470 °C)
Distance from Earth 211.98 light-years
Earth Similarity Index 0.312
Travel time at Voyager 1 speed 3,738,317 years

3 siblings around TOI-1203

TOI-1203.01 shares its host star with 3 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
TOI-1203 b	Super-Earth	1.52	3.51	4.157	1,361	2025
TOI-1203 c	Sub-Neptune	2.20	5.46	13.077	—	2025
TOI-1203.01 this	Sub-Neptune	2.92	7.39	25.503	744	2021
TOI-1203 e	Neptune-like	7.31	42.10	204.590	—	2025

TOI-1203.01 Planet Profile

Physical Specs

Radius

2.92 R⊕

Radius (Jupiter)

0.260 R♃

Mass

7.39 M⊕

Mass (Jupiter)

0.023 M♃

Density

1.63 g/cm³

Surface Gravity

0.87 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.312

HZ Position Inner

Controversial No

Discovery

Year 2021

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#605of 1978

top 30.5%

This planet

2.92R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1475 b 2.92 R⊕ HD 136352 c 2.92 R⊕ Kepler-153 b 2.92 R⊕

Metric	Earth	TOI-1203.01	Jupiter
Radius (R⊕)	1.00	2.92	11.21
Mass (M⊕)	1.00	7.39	317.83
Density (g/cm³)	5.51	1.63	1.33
Surface Gravity (g)	1.00	0.87	2.53
Insolation (S⊕)	1.00	51.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	7.390 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HIP

HIP 54779

TIC

TIC 23434737

Gaia DR2

Gaia DR2 5402390257832925952

Gaia DR3

Gaia DR3 5402390257832925952

System

TOI-1203

Percentile among Sub-Neptune cohort

Radius 2.918 R⊕ · percentile 69 / cohort 1978

Mass 7.390 M⊕ · percentile 46 / cohort 1978

Orbital period 25.50 d · percentile 69 / cohort 1946

Distance 64.99 pc · percentile 15 / cohort 1975

ESI 0.312 · percentile 31 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

25.503 days

Semi-major axis

0.1632 AU

Eccentricity

0.032

Inclination

89.22 °

Year Length

A year here lasts approximately 25.50 Earth days (7.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1632 AU.

Transit Fingerprint

Depth

0.056 %

Duration

6.153 h

Impact parameter b

0.407

Rp / R★

0.022690

Transit midpoint (BJD)

2,458,553.0711

Photometric dip

Transit produces a flux drop of 558 ppm lasting ≈ 6.15 h.

Extended Orbital Architecture

Planet / star radius ratio

0.022690

Semi-major axis / stellar radius

29.770

Impact parameter (b)

0.407

RV semi-amplitude (K)

1.740 m/s

Transit mid-time (BJD)

2,458,553.0711

Long. of periastron (ω)

186.40°

Angular separation (arcsec)

2.51000

Eq. Temperature

744K

(470 °C)

Insolation (S⊕)

51.00

Earth = 1.00

Earth Similarity (ESI)

0.312

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

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

Giacalone et al. 2021

Instrument

TESS CCD Array

Publication

2021-01

Observation locale

Space

Discovery cohort

Planets confirmed in 2021 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-2257 b · Sub-Neptune TOI-2285 b · Super-Earth TOI-1231 b · Sub-Neptune AU Mic c · Sub-Neptune LHS 1678 c · Rocky Terrestrial LHS 1478 b · Rocky Terrestrial TOI-2406 b · Sub-Neptune HD 207897 b · Sub-Neptune TOI-269 b · Sub-Neptune TIC 172900988 b · Gas Giant TOI-178 g · Sub-Neptune TOI-2076 d · Sub-Neptune

Host System: TOI-1203

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,737 K — cooler than the Sun (5,778 K)

Estimated Age

12.50 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.179 R☉

Stellar Mass

0.886 M☉

Metallicity [Fe/H]

-0.39

Extended Stellar Properties

Surface gravity (log g)

4.340 dex

Stellar density

0.767 g/cm³

Systemic radial velocity

72.66 km/s

Rotational v·sin i

1.40 km/s

Activity index (log R'HK)

-4.998

Metallicity ratio

[Fe/H]

Distance

64.99 parsec

Light-years 211.98 ly

V-band magnitude

8.59 mag

Voyager-speed travel 3,738,317 yr

Multi-band Host Photometry — 7 bands

Astrometric Data

Parallax

15.357 mas

Total Proper Motion

296.334 mas/yr

PM Right Ascension

292.93 mas/yr

PM Declination

-44.78 mas/yr

Galactic Cartesian (pc)

x = -0.808 · y = 0.168 · z = -0.565

Equatorial (J2000)

RA 168.22674° · Dec -34.40694°

Galactic ℓ, b

280.785° · 24.192°

Ecliptic λ, β

184.972° · -35.831°

HTM-20 index

-493628253