Key parameters at a glance

A radius of 2.72 Earth radii
A mass of 7.85 Earth masses
Surface gravity around 1.06 g
An orbital period of 5.078 days
Semi-major axis 0.0392 AU
Equilibrium temperature 471 K (198 °C)
Distance from Earth 202.60 light-years
Earth Similarity Index 0.506
Travel time at Voyager 1 speed 3,572,879 years
Almost certainly tidally locked to its host star given the close orbit

TOI-122 b Planet Profile

Physical Specs

Radius

2.72 R⊕

Radius (Jupiter)

0.243 R♃

Mass

7.85 M⊕

Mass (Jupiter)

0.025 M♃

Density

2.14 g/cm³

Surface Gravity

1.06 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.506

HZ Position Inner

Controversial No

Discovery

Year 2020

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#838of 1978

top 42.3%

This planet

2.72R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-26 c 2.72 R⊕ Kepler-351 d 2.72 R⊕ Kepler-358 b 2.72 R⊕

Metric	Earth	TOI-122 b	Jupiter
Radius (R⊕)	1.00	2.72	11.21
Mass (M⊕)	1.00	7.85	317.83
Density (g/cm³)	5.51	2.14	1.33
Surface Gravity (g)	1.00	1.06	2.53
Insolation (S⊕)	1.00	8.80	0.037

Star Catalogue Identifiers

TIC

TIC 231702397

Gaia DR2

Gaia DR2 6411096106487783296

Gaia DR3

Gaia DR3 6411096106487783296

System

TOI-122

Percentile among Sub-Neptune cohort

Radius 2.720 R⊕ · percentile 57 / cohort 1978

Mass 7.850 M⊕ · percentile 53 / cohort 1978

Orbital period 5.08 d · percentile 12 / cohort 1946

Distance 62.12 pc · percentile 14 / cohort 1975

ESI 0.506 · percentile 71 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

5.078 days

Semi-major axis

0.0392 AU

Eccentricity

0.000

Inclination

88.40 °

Year Length

A year here lasts approximately 5.08 Earth days (1.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0392 AU.

Transit Fingerprint

Depth

0.560 %

Duration

1.210 h

Impact parameter b

0.720

Rp / R★

0.075000

Transit midpoint (BJD)

2,458,425.6026

Photometric dip

Transit produces a flux drop of 5,600 ppm lasting ≈ 1.21 h.

Extended Orbital Architecture

Planet / star radius ratio

0.075000

Semi-major axis / stellar radius

25.200

Impact parameter (b)

0.720

Transit mid-time (BJD)

2,458,425.6026

Angular separation (arcsec)

0.63100

Eq. Temperature

471K

(198 °C)

Insolation (S⊕)

8.80

Earth = 1.00

Earth Similarity (ESI)

0.506

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.

Discovery Paper

Primary reference

Waalkes et al. 2021

Instrument

TESS CCD Array

Publication

2021-01

Observation locale

Space

Discovery cohort

Planets confirmed in 2020 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-700 d · Rocky Terrestrial TOI-237 b · Super-Earth TOI-700 b · Rocky Terrestrial TOI-1266 c · Super-Earth LTT 3780 c · Sub-Neptune TOI-700 c · Sub-Neptune TOI-776 c · Sub-Neptune TOI-942 c · Neptune-like TOI-776 b · Super-Earth TOI-1266 b · Sub-Neptune TOI-540 b · Rocky Terrestrial LHS 1815 b · Rocky Terrestrial

Host System: TOI-122

Spectral Class

M-type red dwarf

Effective Temperature

3,403 K — cooler than the Sun (5,778 K)

Estimated Age

2.00 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.334 R☉

Stellar Mass

0.312 M☉

Metallicity [Fe/H]

—

Extended Stellar Properties

Surface gravity (log g)

4.880 dex

Stellar density

12.800 g/cm³

Systemic radial velocity

-72.40 km/s

Rotational v·sin i

7.20 km/s

Rotation period

72.00 days

Distance

62.12 parsec

Light-years 202.60 ly

V-band magnitude

15.53 mag

Voyager-speed travel 3,572,879 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

16.070 mas

Total Proper Motion

273.292 mas/yr

PM Right Ascension

138.14 mas/yr

PM Declination

-235.81 mas/yr

Galactic Cartesian (pc)

x = 0.459 · y = -0.235 · z = -0.857

Equatorial (J2000)

RA 332.94824° · Dec -58.94609°

Galactic ℓ, b

332.557° · -47.969°

Ecliptic λ, β

309.562° · -43.842°

HTM-20 index

1927567068