Key parameters at a glance

A radius of 1.63 Earth radii
A mass of 1.64 Earth masses
Surface gravity around 0.62 g
An orbital period of 7.451 days
Semi-major axis 0.0494 AU
Equilibrium temperature 416 K (143 °C)
Distance from Earth 34.64 light-years
Earth Similarity Index 0.626
Travel time at Voyager 1 speed 610,802 years
Almost certainly tidally locked to its host star given the close orbit

4 siblings around L 98-59

L 98-59 d shares its host star with 4 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
L 98-59 b	Rocky Terrestrial	0.84	0.46	2.253	620	2019
L 98-59 c	Super-Earth	1.33	2.00	3.691	526	2019
L 98-59 d this	Super-Earth	1.63	1.64	7.451	416	2019
L 98-59 e	Super-Earth	1.49	2.82	12.828	347	2021
L 98-59 f	Super-Earth	1.48	2.80	23.064	285	2025

L 98-59 d Planet Profile

Physical Specs

Radius

1.63 R⊕

Radius (Jupiter)

0.145 R♃

Mass

1.64 M⊕

Mass (Jupiter)

0.005 M♃

Density

2.20 g/cm³

Surface Gravity

0.62 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.626

HZ Position Inner

Controversial No

Discovery

Year 2019

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#529of 1176

top 44.9%

This planet

1.63R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-1873 b 1.63 R⊕ Kepler-319 b 1.63 R⊕ Kepler-202 b 1.63 R⊕

Metric	Earth	L 98-59 d	Jupiter
Radius (R⊕)	1.00	1.63	11.21
Mass (M⊕)	1.00	1.64	317.83
Density (g/cm³)	5.51	2.20	1.33
Surface Gravity (g)	1.00	0.62	2.53
Insolation (S⊕)	1.00	4.97	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	1.640 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 307210830

Gaia DR2

Gaia DR2 5271055243163629056

Gaia DR3

Gaia DR3 5271055243163629056

System

L 98-59

Percentile among Super-Earth cohort

Radius 1.627 R⊕ · percentile 55 / cohort 1176

Mass 1.640 M⊕ · percentile 1 / cohort 1176

Orbital period 7.45 d · percentile 55 / cohort 1164

Distance 10.62 pc · percentile 2 / cohort 1171

ESI 0.626 · percentile 82 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

7.451 days

Semi-major axis

0.0494 AU

Eccentricity

0.006

Inclination

88.44 °

Year Length

A year here lasts approximately 7.45 Earth days (2.0% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0494 AU.

Transit Fingerprint

Depth

0.145 %

Duration

0.840 h

Impact parameter b

0.921

Rp / R★

0.046000

Transit midpoint (BJD)

2,458,362.7400

Photometric dip

Transit produces a flux drop of 1,445 ppm lasting ≈ 0.84 h.

Extended Orbital Architecture

Planet / star radius ratio

0.046000

Semi-major axis / stellar radius

33.933

Impact parameter (b)

0.921

RV semi-amplitude (K)

1.390 m/s

Transit mid-time (BJD)

2,458,362.7400

Long. of periastron (ω)

180.00°

Angular separation (arcsec)

4.65000

Eq. Temperature

416K

(143 °C)

Insolation (S⊕)

4.97

Earth = 1.00

Earth Similarity (ESI)

0.626

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

Kostov et al. 2019

Instrument

TESS CCD Array

Publication

2019-07

Observation locale

Space

Discovery cohort

Planets confirmed in 2019 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

LP 791-18 c · Sub-Neptune LTT 1445 A b · Super-Earth TOI-270 d · Sub-Neptune GJ 357 b · Rocky Terrestrial GJ 143 b · Sub-Neptune HD 23472 c · Super-Earth L 98-59 c · Super-Earth LP 791-18 b · Rocky Terrestrial TOI-270 c · Sub-Neptune HD 23472 b · Sub-Neptune TOI-270 b · Super-Earth L 98-59 b · Rocky Terrestrial

Host System: L 98-59

Spectral Class

M-type red dwarf

Effective Temperature

3,415 K — cooler than the Sun (5,778 K)

Estimated Age

4.94 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.316 R☉

Stellar Mass

0.292 M☉

Metallicity [Fe/H]

-0.46

Extended Stellar Properties

Surface gravity (log g)

4.910 dex

Stellar density

13.000 g/cm³

Systemic radial velocity

-5.68 km/s

Rotational v·sin i

0.00 km/s

Rotation period

77.50 days

Metallicity ratio

[Fe/H]

Distance

10.62 parsec

Light-years 34.64 ly

V-band magnitude

11.69 mag

Voyager-speed travel 610,802 yr

Multi-band Host Photometry — 13 bands

Astrometric Data

Parallax

94.139 mas

Total Proper Motion

353.413 mas/yr

PM Right Ascension

94.77 mas/yr

PM Declination

-340.47 mas/yr

Galactic Cartesian (pc)

x = -0.209 · y = 0.304 · z = -0.929

Equatorial (J2000)

RA 124.53286° · Dec -68.31447°

Galactic ℓ, b

281.817° · -17.593°

Ecliptic λ, β

203.326° · -76.814°

HTM-20 index

1081502068