Key parameters at a glance

A radius of 1.09 Earth radii
A mass of 1.58 Earth masses
Surface gravity around 1.33 g
An orbital period of 3.814 days
Semi-major axis 0.0404 AU
Equilibrium temperature 617 K (344 °C)
Distance from Earth 97.33 light-years
Earth Similarity Index 0.506
Travel time at Voyager 1 speed 1,716,463 years
Almost certainly tidally locked to its host star given the close orbit

LHS 1815 b Planet Profile

Physical Specs

Radius

1.09 R⊕

Radius (Jupiter)

0.097 R♃

Mass

1.58 M⊕

Mass (Jupiter)

0.005 M♃

Density

6.70 g/cm³

Surface Gravity

1.33 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.506

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

#252of 570

top 44.0%

This planet

1.09R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-1956 b 1.09 R⊕ TOI-5720 b 1.09 R⊕ Kepler-212 b 1.09 R⊕

Metric	Earth	LHS 1815 b	Jupiter
Radius (R⊕)	1.00	1.09	11.21
Mass (M⊕)	1.00	1.58	317.83
Density (g/cm³)	5.51	6.70	1.33
Surface Gravity (g)	1.00	1.33	2.53
Insolation (S⊕)	1.00	26.37	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	1.580 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HIP

HIP 28754

TIC

TIC 260004324

Gaia DR2

Gaia DR2 5500061456275483776

Gaia DR3

Gaia DR3 5500061456275483776

System

LHS 1815

Percentile among Rocky Terrestrial cohort

Radius 1.088 R⊕ · percentile 56 / cohort 570

Mass 1.580 M⊕ · percentile 65 / cohort 570

Orbital period 3.81 d · percentile 41 / cohort 567

Distance 29.84 pc · percentile 13 / cohort 566

ESI 0.506 · percentile 71 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

3.814 days

Semi-major axis

0.0404 AU

Eccentricity

0.000

Inclination

88.13 °

Year Length

A year here lasts approximately 3.81 Earth days (1.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0404 AU.

Transit Fingerprint

Depth

0.046 %

Duration

1.379 h

Impact parameter b

0.510

Rp / R★

0.019900

Transit midpoint (BJD)

2,458,327.4161

Photometric dip

Transit produces a flux drop of 458 ppm lasting ≈ 1.38 h.

Extended Orbital Architecture

Planet / star radius ratio

0.019900

Semi-major axis / stellar radius

17.403

Impact parameter (b)

0.510

RV semi-amplitude (K)

1.020 m/s

Transit mid-time (BJD)

2,458,327.4161

Long. of periastron (ω)

90.00°

Angular separation (arcsec)

1.35000

Eq. Temperature

617K

(344 °C)

Insolation (S⊕)

26.37

Earth = 1.00

Earth Similarity (ESI)

0.506

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

Gan et al. 2020

Instrument

TESS CCD Array

Publication

2020-04

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 TOI-122 b · Sub-Neptune

Host System: LHS 1815

Spectral Class

M-type red dwarf

Effective Temperature

3,643 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.501 R☉

Stellar Mass

0.502 M☉

Metallicity [Fe/H]

-0.12

Extended Stellar Properties

Surface gravity (log g)

4.770 dex

Stellar density

5.600 g/cm³

Systemic radial velocity

42.22 km/s

Rotation period

47.80 days

Metallicity ratio

[Fe/H]

Distance

29.84 parsec

Light-years 97.33 ly

V-band magnitude

12.17 mag

Voyager-speed travel 1,716,463 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

33.481 mas

Total Proper Motion

762.761 mas/yr

PM Right Ascension

681.73 mas/yr

PM Declination

342.13 mas/yr

Galactic Cartesian (pc)

x = -0.011 · y = 0.569 · z = -0.822

Equatorial (J2000)

RA 91.08999° · Dec -55.31154°

Galactic ℓ, b

263.556° · -28.571°

Ecliptic λ, β

93.174° · -78.739°

HTM-20 index

169509354

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