Key parameters at a glance

A radius of 1.24 Earth radii
A mass of 2.14 Earth masses
Surface gravity around 1.39 g
An orbital period of 2.770 days
Semi-major axis 0.0293 AU
Equilibrium temperature 709 K (436 °C)
Distance from Earth 32.63 light-years
Earth Similarity Index 0.439
Travel time at Voyager 1 speed 575,492 years
Almost certainly tidally locked to its host star given the close orbit

Context from the literature

HD 260655 is a relatively bright and cool M0 V red dwarf star located 33 light-years away from the Solar System in the constellation of Gemini. HD 260655 has two confirmed rocky planets, named HD 260655 b and HD 260655 c, that were discovered in 2022. Both planets were detected by the TESS mission and confirmed independently with archival and new precise radial velocity data obtained with the HIRES observatory since 1998, and the CARMENES survey instruments since 2016.

Excerpted from Wikipedia · full article

1 sibling around HD 260655

HD 260655 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
HD 260655 b this	Rocky Terrestrial	1.24	2.14	2.770	709	2022
HD 260655 c	Super-Earth	1.53	3.09	5.706	557	2022

HD 260655 b Planet Profile

Physical Specs

Radius

1.24 R⊕

Radius (Jupiter)

0.111 R♃

Mass

2.14 M⊕

Mass (Jupiter)

0.007 M♃

Density

6.20 g/cm³

Surface Gravity

1.39 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.439

HZ Position Inner

Controversial No

Discovery

Year 2022

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#4of 570

top 0.5%

This planet

1.24R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-354 d 1.24 R⊕ Kepler-373 c 1.24 R⊕ Kepler-383 c 1.24 R⊕

Metric	Earth	HD 260655 b	Jupiter
Radius (R⊕)	1.00	1.24	11.21
Mass (M⊕)	1.00	2.14	317.83
Density (g/cm³)	5.51	6.20	1.33
Surface Gravity (g)	1.00	1.39	2.53
Insolation (S⊕)	1.00	42.20	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	2.140 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HD 260655

HIP

HIP 31635

TIC

TIC 307809773

Gaia DR2

Gaia DR2 3359074685047632640

Gaia DR3

Gaia DR3 3359074685047632640

System

HD 260655

Percentile among Rocky Terrestrial cohort

Radius 1.240 R⊕ · percentile 98 / cohort 570

Mass 2.140 M⊕ · percentile 91 / cohort 570

Orbital period 2.77 d · percentile 32 / cohort 567

Distance 10.01 pc · percentile 5 / cohort 566

ESI 0.439 · percentile 64 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

2.770 days

Semi-major axis

0.0293 AU

Eccentricity

0.039

Inclination

87.35 °

Year Length

A year here lasts approximately 2.77 Earth days (0.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0293 AU.

Transit Fingerprint

Depth

0.071 %

Duration

1.150 h

Impact parameter b

0.665

Rp / R★

0.025860

Transit midpoint (BJD)

2,459,497.9102

Photometric dip

Transit produces a flux drop of 712 ppm lasting ≈ 1.15 h.

Extended Orbital Architecture

Planet / star radius ratio

0.025860

Semi-major axis / stellar radius

14.430

Impact parameter (b)

0.665

RV semi-amplitude (K)

1.690 m/s

Transit mid-time (BJD)

2,459,497.9102

Long. of periastron (ω)

57.00°

Angular separation (arcsec)

2.93000

Eq. Temperature

709K

(436 °C)

Insolation (S⊕)

42.20

Earth = 1.00

Earth Similarity (ESI)

0.439

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.

Discovery Paper

Primary reference

Luque et al. 2022

Instrument

TESS CCD Array

Publication

2022-04

Observation locale

Space

Discovery cohort

Planets confirmed in 2022 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-1452 b · Super-Earth TOI-712 d · Sub-Neptune TOI-1468 c · Sub-Neptune TOI-2136 b · Sub-Neptune LTT 1445 A c · Rocky Terrestrial TOI-712 c · Sub-Neptune LP 890-9 b · Super-Earth TOI-2081 b · Sub-Neptune GJ 3929 b · Rocky Terrestrial HD 260655 c · Super-Earth HD 73583 c · Sub-Neptune TOI-1759 b · Sub-Neptune

Host System: HD 260655

Spectral Class

M-type red dwarf

Effective Temperature

3,803 K — cooler than the Sun (5,778 K)

Estimated Age

5.00 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.439 R☉

Stellar Mass

0.439 M☉

Metallicity [Fe/H]

-0.43

Extended Stellar Properties

Surface gravity (log g)

5.200 dex

Stellar density

7.300 g/cm³

Systemic radial velocity

-58.75 km/s

Rotational v·sin i

2.00 km/s

Rotation period

37.50 days

Activity index (log R'HK)

-4.840

Metallicity ratio

[Fe/H]

Distance

10.01 parsec

Light-years 32.63 ly

V-band magnitude

9.63 mag

Voyager-speed travel 575,492 yr

Multi-band Host Photometry — 8 bands

Astrometric Data

Parallax

99.916 mas

Total Proper Motion

835.825 mas/yr

PM Right Ascension

-764.52 mas/yr

PM Declination

337.80 mas/yr

Galactic Cartesian (pc)

x = -0.154 · y = 0.941 · z = 0.302

Equatorial (J2000)

RA 99.29154° · Dec 17.56627°

Galactic ℓ, b

195.671° · 4.865°

Ecliptic λ, β

98.893° · -5.587°

HTM-20 index

551488580

Observation Record

Photometric series

Stellar spectra

Archive notes

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