Key parameters at a glance

A radius of 2.93 Earth radii
A mass of 8.91 Earth masses
Surface gravity around 1.04 g
An orbital period of 5.583 days
Semi-major axis 0.0412 AU
Equilibrium temperature 448 K (175 °C)
Distance from Earth 154.42 light-years
Earth Similarity Index 0.513
Travel time at Voyager 1 speed 2,723,137 years
Almost certainly tidally locked to its host star given the close orbit

1 sibling around TOI-2015

TOI-2015 c 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-2015 b	Sub-Neptune	3.31	9.20	3.348	531	2023
TOI-2015 c this	Sub-Neptune	2.93	8.91	5.583	448	2025

TOI-2015 c Planet Profile

Physical Specs

Radius

2.93 R⊕

Radius (Jupiter)

0.261 R♃

Mass

8.91 M⊕

Mass (Jupiter)

0.028 M♃

Density

1.95 g/cm³

Surface Gravity

1.04 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.513

HZ Position Inner

Controversial No

Discovery

Year 2025

Method Transit Timing Variations

Facility Multiple Observatories

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#585of 1978

top 29.5%

This planet

2.93R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

TOI-451 c 2.93 R⊕ Kepler-221 c 2.93 R⊕ TOI-125 d 2.93 R⊕

Metric	Earth	TOI-2015 c	Jupiter
Radius (R⊕)	1.00	2.93	11.21
Mass (M⊕)	1.00	8.91	317.83
Density (g/cm³)	5.51	1.95	1.33
Surface Gravity (g)	1.00	1.04	2.53
Insolation (S⊕)	1.00	6.68	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	8.910 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 368287008

Gaia DR2

Gaia DR2 1270814787767025408

Gaia DR3

Gaia DR3 1270814787767025408

System

TOI-2015

Percentile among Sub-Neptune cohort

Radius 2.930 R⊕ · percentile 70 / cohort 1978

Mass 8.910 M⊕ · percentile 64 / cohort 1978

Orbital period 5.58 d · percentile 15 / cohort 1946

Distance 47.34 pc · percentile 11 / cohort 1975

ESI 0.513 · percentile 72 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

5.583 days

Semi-major axis

0.0412 AU

Eccentricity

0.000

Inclination

85.70 °

Year Length

A year here lasts approximately 5.58 Earth days (1.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0412 AU.

Eq. Temperature

448K

(175 °C)

Insolation (S⊕)

6.68

Earth = 1.00

Earth Similarity (ESI)

0.513

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

Barkaoui et al. 2025

Instrument

Multiple Instruments

Publication

2025-02

Observation locale

Ground

Discovery cohort

Planets confirmed in 2025 at Multiple Observatories (12 shown).

Gl 725 A b · Super-Earth HD 20794 f · Sub-Neptune GJ 3998 d · Sub-Neptune GJ 251 c · Super-Earth HD 86728 b · Sub-Neptune Kepler-139 f · Neptune-like HD 73344 d · Gas Giant TOI-1472 c · Sub-Neptune TOI-6695 c · Gas Giant AT2021ueyL b · Gas Giant HIP 111909 b · Gas Giant TOI-6041 c · Gas Giant

Host System: TOI-2015

Spectral Class

M-type red dwarf

Effective Temperature

3,297 K — cooler than the Sun (5,778 K)

Estimated Age

5.50 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.327 R☉

Stellar Mass

0.304 M☉

Metallicity [Fe/H]

-0.31

Extended Stellar Properties

Surface gravity (log g)

5.040 dex

Stellar density

11.800 g/cm³

Systemic radial velocity

-32.04 km/s

Rotational v·sin i

2.00 km/s

Rotation period

8.70 days

Metallicity ratio

[Fe/H]

Distance

47.34 parsec

Light-years 154.42 ly

V-band magnitude

16.11 mag

Voyager-speed travel 2,723,137 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

21.093 mas

Total Proper Motion

85.126 mas/yr

PM Right Ascension

-56.17 mas/yr

PM Declination

63.97 mas/yr

Galactic Cartesian (pc)

x = -0.545 · y = -0.701 · z = 0.460

Equatorial (J2000)

RA 232.13265° · Dec 27.36107°

Galactic ℓ, b

42.576° · 55.232°

Ecliptic λ, β

220.181° · 44.472°

HTM-20 index

1554128141