Key parameters at a glance

A radius of 3.66 Earth radii
A mass of 13.02 Earth masses
Surface gravity around 0.97 g
An orbital period of 3.822 days
Semi-major axis 0.0394 AU
Equilibrium temperature 830 K (557 °C)
Distance from Earth 48.77 light-years
Earth Similarity Index 0.261
Travel time at Voyager 1 speed 860,147 years
Almost certainly tidally locked to its host star given the close orbit

Gl 378 b Planet Profile

Physical Specs

Radius

3.66 R⊕

Radius (Jupiter)

0.327 R♃

Mass

13.02 M⊕

Mass (Jupiter)

0.041 M♃

Density

1.46 g/cm³

Surface Gravity

0.97 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.261

HZ Position Unknown

Controversial No

Discovery

Year 2019

Method Radial Velocity

Facility Haute-Provence Observatory

Telescope 1.93 m Telescope

Size rank in cohort

Rank by radius

#107of 1978

top 5.4%

This planet

3.66R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

TOI-1691 b 3.66 R⊕ TOI-1130 b 3.66 R⊕ GJ 27.1 b 3.66 R⊕

Metric	Earth	Gl 378 b	Jupiter
Radius (R⊕)	1.00	3.66	11.21
Mass (M⊕)	1.00	13.02	317.83
Density (g/cm³)	5.51	1.46	1.33
Surface Gravity (g)	1.00	0.97	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	13.020 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 49189

TIC

TIC 252470070

Gaia DR2

Gaia DR2 823228721066990720

Gaia DR3

Gaia DR3 823228721067307392

System

Gl 378

Percentile among Sub-Neptune cohort

Radius 3.660 R⊕ · percentile 94 / cohort 1978

Mass 13.020 M⊕ · percentile 88 / cohort 1978

Orbital period 3.82 d · percentile 8 / cohort 1946

Distance 14.95 pc · percentile 3 / cohort 1975

ESI 0.261 · percentile 19 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

3.822 days

Semi-major axis

0.0394 AU

Eccentricity

0.109

Inclination

— °

Year Length

A year here lasts approximately 3.82 Earth days (1.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0394 AU.

Eq. Temperature

830K

(557 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.261

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

Hobson et al. 2019

Instrument

SOPHIE Spectrograph

Publication

2019-05

Observation locale

Ground

Host System: Gl 378

Spectral Class

M-type red dwarf

Effective Temperature

3,879 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.560 R☉

Stellar Mass

0.560 M☉

Metallicity [Fe/H]

0.06

Extended Stellar Properties

Surface gravity (log g)

4.685 dex

Stellar density

4.445 g/cm³

Systemic radial velocity

-9.70 km/s

Metallicity ratio

[Fe/H]

Distance

14.95 parsec

Light-years 48.77 ly

V-band magnitude

10.03 mag

Voyager-speed travel 860,147 yr

Multi-band Host Photometry — 13 bands

Astrometric Data

Parallax

66.841 mas

Total Proper Motion

1,605.102 mas/yr

PM Right Ascension

-633.08 mas/yr

PM Declination

-1,474.98 mas/yr

Galactic Cartesian (pc)

x = -0.582 · y = 0.328 · z = 0.744

Equatorial (J2000)

RA 150.58655° · Dec 48.08245°

Galactic ℓ, b

168.743° · 51.192°

Ecliptic λ, β

134.264° · 33.518°

HTM-20 index

1002150183