Key parameters at a glance

A radius of 1.19 Earth radii
A mass of 1.32 Earth masses
Surface gravity around 0.93 g
An orbital period of 0.518 days
Semi-major axis 0.0092 AU
Equilibrium temperature 1,089 K (816 °C)
Distance from Earth 66.45 light-years
Earth Similarity Index 0.280
Travel time at Voyager 1 speed 1,171,806 years
Almost certainly tidally locked to its host star given the close orbit

GJ 1252 b Planet Profile

Physical Specs

Radius

1.19 R⊕

Radius (Jupiter)

0.106 R♃

Mass

1.32 M⊕

Mass (Jupiter)

0.004 M♃

Density

4.20 g/cm³

Surface Gravity

0.93 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.280

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

#98of 570

top 17.0%

This planet

1.19R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-1735 b 1.19 R⊕ GJ 1132 b 1.19 R⊕ K2-384 c 1.19 R⊕

Metric	Earth	GJ 1252 b	Jupiter
Radius (R⊕)	1.00	1.19	11.21
Mass (M⊕)	1.00	1.32	317.83
Density (g/cm³)	5.51	4.20	1.33
Surface Gravity (g)	1.00	0.93	2.53
Insolation (S⊕)	1.00	233.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	1.320 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 370133522

Gaia DR2

Gaia DR2 6468968316900356736

Gaia DR3

Gaia DR3 6468968316900356736

System

GJ 1252

Percentile among Rocky Terrestrial cohort

Radius 1.193 R⊕ · percentile 83 / cohort 570

Mass 1.320 M⊕ · percentile 51 / cohort 570

Orbital period 0.52 d · percentile 3 / cohort 567

Distance 20.37 pc · percentile 10 / cohort 566

ESI 0.280 · percentile 32 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

0.518 days

Semi-major axis

0.0092 AU

Eccentricity

0.000

Inclination

85.00 °

Year Length

A year here lasts roughly 12.4 hours long on a nearly circular orbit at a mean orbital distance of 0.0092 AU.

Transit Fingerprint

Depth

0.083 %

Duration

0.724 h

Impact parameter b

0.440

Rp / R★

0.028020

Transit midpoint (BJD)

2,458,668.0974

Photometric dip

Transit produces a flux drop of 832 ppm lasting ≈ 0.72 h.

Extended Orbital Architecture

Planet / star radius ratio

0.028020

Semi-major axis / stellar radius

5.030

Impact parameter (b)

0.440

RV semi-amplitude (K)

2.000 m/s

Transit mid-time (BJD)

2,458,668.0974

Long. of periastron (ω)

90.00°

Angular separation (arcsec)

0.44900

Eq. Temperature

1,089K

(816 °C)

Insolation (S⊕)

233.00

Earth = 1.00

Earth Similarity (ESI)

0.280

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

Shporer et al. 2020

Instrument

TESS CCD Array

Publication

2020-02

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: GJ 1252

Spectral Class

M-type red dwarf

Effective Temperature

3,458 K — cooler than the Sun (5,778 K)

Estimated Age

3.90 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.391 R☉

Stellar Mass

0.381 M☉

Metallicity [Fe/H]

0.10

Extended Stellar Properties

Surface gravity (log g)

4.887 dex

Stellar density

8.993 g/cm³

Systemic radial velocity

7.48 km/s

Rotation period

64.00 days

Metallicity ratio

[Fe/H]

Distance

20.37 parsec

Light-years 66.45 ly

V-band magnitude

12.68 mag

Voyager-speed travel 1,171,806 yr

Multi-band Host Photometry — 7 bands

Astrometric Data

Parallax

49.056 mas

Total Proper Motion

1,301.750 mas/yr

PM Right Ascension

424.41 mas/yr

PM Declination

-1,230.62 mas/yr

Galactic Cartesian (pc)

x = 0.332 · y = -0.442 · z = -0.834

Equatorial (J2000)

RA 306.92865° · Dec -56.46229°

Galactic ℓ, b

341.217° · -35.493°

Ecliptic λ, β

294.250° · -36.091°

HTM-20 index

-981710771