Key parameters at a glance

A radius of 2.52 Earth radii
A mass of 4.46 Earth masses
Surface gravity around 0.70 g
An orbital period of 10.895 days
Semi-major axis 0.0730 AU
Equilibrium temperature 415 K (142 °C)
Distance from Earth 117.45 light-years
Earth Similarity Index 0.545
Travel time at Voyager 1 speed 2,071,313 years
Almost certainly tidally locked to its host star given the close orbit

2 siblings around TOI-1266

TOI-1266 b shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
TOI-1266 b this	Sub-Neptune	2.52	4.46	10.895	415	2020
TOI-1266 c	Super-Earth	1.98	3.17	18.803	346	2020
TOI-1266 d	Super-Earth	1.74	3.68	32.509	288	2025

TOI-1266 b Planet Profile

Physical Specs

Radius

2.52 R⊕

Radius (Jupiter)

0.225 R♃

Mass

4.46 M⊕

Mass (Jupiter)

0.014 M♃

Density

1.54 g/cm³

Surface Gravity

0.70 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.545

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

#1147of 1978

top 57.9%

This planet

2.52R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-748 b 2.52 R⊕ Kepler-129 c 2.52 R⊕ TOI-1749 d 2.52 R⊕

Metric	Earth	TOI-1266 b	Jupiter
Radius (R⊕)	1.00	2.52	11.21
Mass (M⊕)	1.00	4.46	317.83
Density (g/cm³)	5.51	1.54	1.33
Surface Gravity (g)	1.00	0.70	2.53
Insolation (S⊕)	1.00	4.72	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	4.460 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 467179528

Gaia DR2

Gaia DR2 1678074272650459008

Gaia DR3

Gaia DR3 1678074272650459008

System

TOI-1266

Percentile among Sub-Neptune cohort

Radius 2.520 R⊕ · percentile 42 / cohort 1978

Mass 4.460 M⊕ · percentile 2 / cohort 1978

Orbital period 10.89 d · percentile 37 / cohort 1946

Distance 36.01 pc · percentile 9 / cohort 1975

ESI 0.545 · percentile 76 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

10.895 days

Semi-major axis

0.0730 AU

Eccentricity

0.039

Inclination

89.13 °

Year Length

A year here lasts approximately 10.89 Earth days (3.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0730 AU.

Transit Fingerprint

Depth

0.317 %

Duration

2.129 h

Impact parameter b

0.549

Rp / R★

0.054500

Transit midpoint (BJD)

2,458,691.0068

Photometric dip

Transit produces a flux drop of 3,168 ppm lasting ≈ 2.13 h.

Extended Orbital Architecture

Planet / star radius ratio

0.054500

Semi-major axis / stellar radius

35.970

Impact parameter (b)

0.549

RV semi-amplitude (K)

2.170 m/s

Transit mid-time (BJD)

2,458,691.0068

Long. of periastron (ω)

0.00°

Angular separation (arcsec)

2.03000

Eq. Temperature

415K

(142 °C)

Insolation (S⊕)

4.72

Earth = 1.00

Earth Similarity (ESI)

0.545

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.

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

Demory et al. 2020

Instrument

TESS CCD Array

Publication

2020-10

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-540 b · Rocky Terrestrial LHS 1815 b · Rocky Terrestrial TOI-122 b · Sub-Neptune

Host System: TOI-1266

Spectral Class

M-type red dwarf

Effective Temperature

3,563 K — cooler than the Sun (5,778 K)

Estimated Age

4.60 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.423 R☉

Stellar Mass

0.437 M☉

Metallicity [Fe/H]

-0.11

Extended Stellar Properties

Surface gravity (log g)

4.826 dex

Stellar density

8.130 g/cm³

Systemic radial velocity

-41.58 km/s

Rotational v·sin i

1.30 km/s

Rotation period

44.60 days

Activity index (log R'HK)

-5.500

Metallicity ratio

[Fe/H]

Distance

36.01 parsec

Light-years 117.45 ly

V-band magnitude

12.94 mag

Voyager-speed travel 2,071,313 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

27.740 mas

Total Proper Motion

152.773 mas/yr

PM Right Ascension

-150.65 mas/yr

PM Declination

-25.37 mas/yr

Galactic Cartesian (pc)

x = -0.389 · y = -0.126 · z = 0.912

Equatorial (J2000)

RA 197.99658° · Dec 65.83370°

Galactic ℓ, b

119.581° · 51.161°

Ecliptic λ, β

147.620° · 62.547°

HTM-20 index

-1935697101