Key parameters at a glance

A radius of 1.24 Earth radii
A mass of 2.33 Earth masses
Surface gravity around 1.51 g
An orbital period of 1.950 days
Semi-major axis 0.0185 AU
Equilibrium temperature 595 K (322 °C)
Distance from Earth 59.45 light-years
Earth Similarity Index 0.512
Travel time at Voyager 1 speed 1,048,408 years
Almost certainly tidally locked to its host star given the close orbit

Context from the literature

LHS 1478 b is a super-Earth exoplanet orbiting around LHS 1478, a red dwarf star located 59.4 light-years from Earth in the constellation of Cassiopeia. It orbits at a distance of 0.018 AU from the star with a inclination of 87° to the plane of the sky. It takes LHS 1478b roughly 1.9 days to complete an orbit around the star.

Excerpted from Wikipedia · full article

LHS 1478 b Planet Profile

Physical Specs

Radius

1.24 R⊕

Radius (Jupiter)

0.111 R♃

Mass

2.33 M⊕

Mass (Jupiter)

0.007 M♃

Density

6.67 g/cm³

Surface Gravity

1.51 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.512

HZ Position Inner

Controversial No

Discovery

Year 2021

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#3of 570

top 0.4%

This planet

1.24R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

TOI-2096 b 1.24 R⊕ Kepler-354 d 1.24 R⊕ K2-83 b 1.24 R⊕

Metric	Earth	LHS 1478 b	Jupiter
Radius (R⊕)	1.00	1.24	11.21
Mass (M⊕)	1.00	2.33	317.83
Density (g/cm³)	5.51	6.67	1.33
Surface Gravity (g)	1.00	1.51	2.53
Insolation (S⊕)	1.00	23.37	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	2.330 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 396562848

Gaia DR2

Gaia DR2 549007291282705024

Gaia DR3

Gaia DR3 549007291282705024

System

LHS 1478

Percentile among Rocky Terrestrial cohort

Radius 1.242 R⊕ · percentile 99 / cohort 570

Mass 2.330 M⊕ · percentile 92 / cohort 570

Orbital period 1.95 d · percentile 22 / cohort 567

Distance 18.23 pc · percentile 9 / cohort 566

ESI 0.512 · percentile 71 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

1.950 days

Semi-major axis

0.0185 AU

Eccentricity

—

Inclination

87.45 °

Year Length

A year here lasts approximately 1.95 Earth days (0.5% of a terrestrial year) at a mean orbital distance of 0.0185 AU.

Transit Fingerprint

Depth

0.209 %

Duration

0.705 h

Impact parameter b

0.717

Rp / R★

0.046200

Transit midpoint (BJD)

2,458,786.7543

Photometric dip

Transit produces a flux drop of 2,089 ppm lasting ≈ 0.71 h.

Extended Orbital Architecture

Planet / star radius ratio

0.046200

Semi-major axis / stellar radius

16.119

Impact parameter (b)

0.717

RV semi-amplitude (K)

3.130 m/s

Transit mid-time (BJD)

2,458,786.7543

Angular separation (arcsec)

1.01000

Eq. Temperature

595K

(322 °C)

Insolation (S⊕)

23.37

Earth = 1.00

Earth Similarity (ESI)

0.512

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

Soto et al. 2021

Instrument

TESS CCD Array

Publication

2021-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2021 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-2257 b · Sub-Neptune TOI-2285 b · Super-Earth TOI-1231 b · Sub-Neptune AU Mic c · Sub-Neptune LHS 1678 c · Rocky Terrestrial TOI-2406 b · Sub-Neptune HD 207897 b · Sub-Neptune TOI-269 b · Sub-Neptune TIC 172900988 b · Gas Giant TOI-178 g · Sub-Neptune TOI-2076 d · Sub-Neptune TOI-1749 d · Sub-Neptune

Host System: LHS 1478

Spectral Class

M-type red dwarf

Effective Temperature

3,381 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.246 R☉

Stellar Mass

0.236 M☉

Metallicity [Fe/H]

-0.13

Extended Stellar Properties

Surface gravity (log g)

4.870 dex

Stellar density

22.200 g/cm³

Rotational v·sin i

2.00 km/s

Metallicity ratio

[Fe/H]

Distance

18.23 parsec

Light-years 59.45 ly

V-band magnitude

13.30 mag

Voyager-speed travel 1,048,408 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

54.833 mas

Total Proper Motion

798.297 mas/yr

PM Right Ascension

691.04 mas/yr

PM Declination

-399.69 mas/yr

Galactic Cartesian (pc)

x = 0.166 · y = 0.163 · z = 0.973

Equatorial (J2000)

RA 44.33887° · Dec 76.55140°

Galactic ℓ, b

130.172° · 15.483°

Ecliptic λ, β

72.755° · 55.860°

HTM-20 index

-58981466

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