Key parameters at a glance

A radius of 11.83 Earth radii
A mass of 184.34 Earth masses
Surface gravity around 1.32 g
An orbital period of 52.978 days
Semi-major axis 0.3026 AU
Equilibrium temperature 759 K (486 °C)
Distance from Earth 371.25 light-years
Earth Similarity Index 0.188
Travel time at Voyager 1 speed 6,546,942 years

1 sibling around TOI-201

TOI-201 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-201 b this	Gas Giant	11.83	184.34	52.978	759	2021
TOI-201 c	Gas Giant	11.13	4,513.16	2,800.000	—	2025

TOI-201 b Planet Profile

Physical Specs

Radius

11.83 R⊕

Radius (Jupiter)

1.055 R♃

Mass

184.34 M⊕

Mass (Jupiter)

0.580 M♃

Density

0.65 g/cm³

Surface Gravity

1.32 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.188

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

#1556of 1771

top 87.8%

This planet

11.83R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

HATS-62 b 11.83 R⊕ TOI-2010 b 11.81 R⊕ K2-115 b 11.80 R⊕

Metric	Earth	TOI-201 b	Jupiter
Radius (R⊕)	1.00	11.83	11.21
Mass (M⊕)	1.00	184.34	317.83
Density (g/cm³)	5.51	0.65	1.33
Surface Gravity (g)	1.00	1.32	2.53
Insolation (S⊕)	1.00	68.45	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	184.340 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HD 39474

HIP

HIP 27515

TIC

TIC 350618622

Gaia DR2

Gaia DR2 4767547667180525696

Gaia DR3

Gaia DR3 4767547667180525696

System

TOI-201

Percentile among Gas Giant cohort

Radius 11.825 R⊕ · percentile 12 / cohort 1771

Mass 184.340 M⊕ · percentile 17 / cohort 1747

Orbital period 52.98 d · percentile 51 / cohort 1533

Distance 113.83 pc · percentile 37 / cohort 1759

ESI 0.188 · percentile 39 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

52.978 days

Semi-major axis

0.3026 AU

Eccentricity

0.318

Inclination

88.75 °

Year Length

A year here lasts approximately 52.98 Earth days (14.5% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.3026 AU.

Transit Fingerprint

Depth

0.657 %

Duration

4.790 h

Impact parameter b

0.729

Rp / R★

0.079190

Transit midpoint (BJD)

2,459,011.7906

Photometric dip

Transit produces a flux drop of 6,569 ppm lasting ≈ 4.79 h.

Extended Orbital Architecture

Planet / star radius ratio

0.079190

Semi-major axis / stellar radius

50.900

Impact parameter (b)

0.729

RV semi-amplitude (K)

27.600 m/s

Transit mid-time (BJD)

2,459,011.7906

Long. of periastron (ω)

81.30°

Angular separation (arcsec)

2.66000

Eq. Temperature

759K

(486 °C)

Insolation (S⊕)

68.45

Earth = 1.00

Earth Similarity (ESI)

0.188

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.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Hobson et al. 2021

Instrument

TESS CCD Array

Publication

2021-05

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-201

Spectral Class

F-type yellow-white

Effective Temperature

6,394 K — hotter than the Sun (5,778 K)

Estimated Age

0.87 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.339 R☉

Stellar Mass

1.316 M☉

Metallicity [Fe/H]

0.24

Extended Stellar Properties

Surface gravity (log g)

4.318 dex

Stellar density

0.810 g/cm³

Systemic radial velocity

16.91 km/s

Rotational v·sin i

9.52 km/s

Metallicity ratio

[Fe/H]

Distance

113.83 parsec

Light-years 371.25 ly

V-band magnitude

9.07 mag

Voyager-speed travel 6,546,942 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

8.757 mas

Total Proper Motion

66.896 mas/yr

PM Right Ascension

7.73 mas/yr

PM Declination

66.45 mas/yr

Galactic Cartesian (pc)

x = 0.026 · y = 0.574 · z = -0.818

Equatorial (J2000)

RA 87.40178° · Dec -54.91042°

Galactic ℓ, b

262.849° · -30.629°

Ecliptic λ, β

82.623° · -78.283°

HTM-20 index

831307443