Key parameters at a glance

A radius of 2.54 Earth radii
A mass of 7.00 Earth masses
Surface gravity around 1.09 g
An orbital period of 62.060 days
Equilibrium temperature 605 K (332 °C)
Distance from Earth 346.67 light-years
Earth Similarity Index 0.415
Travel time at Voyager 1 speed 6,113,489 years

5 siblings around HIP 41378

HIP 41378 g shares its host star with 5 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
HIP 41378 b	Sub-Neptune	2.60	6.89	15.572	959	2016
HIP 41378 c	Sub-Neptune	2.73	4.40	31.706	757	2016
HIP 41378 g this	Sub-Neptune	2.54	7.00	62.060	605	2025
HIP 41378 d	Sub-Neptune	3.54	4.60	278.362	367	2016
HIP 41378 e	Neptune-like	4.92	12.00	369.000	335	2016
HIP 41378 f	Neptune-like	9.20	12.00	542.080	294	2016

HIP 41378 g Planet Profile

Physical Specs

Radius

2.54 R⊕

Radius (Jupiter)

0.227 R♃

Mass

7.00 M⊕

Mass (Jupiter)

0.022 M♃

Density

2.35 g/cm³

Surface Gravity

1.09 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.415

HZ Position Inner

Controversial No

Discovery

Year 2025

Method Radial Velocity

Facility W. M. Keck Observatory

Telescope 10 m Keck I Telescope

Size rank in cohort

Rank by radius

#1117of 1978

top 56.4%

This planet

2.54R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1116 b 2.54 R⊕ Kepler-325 c 2.54 R⊕ HD 189567 c 2.54 R⊕

Metric	Earth	HIP 41378 g	Jupiter
Radius (R⊕)	1.00	2.54	11.21
Mass (M⊕)	1.00	7.00	317.83
Density (g/cm³)	5.51	2.35	1.33
Surface Gravity (g)	1.00	1.09	2.53
Insolation (S⊕)	1.00	22.30	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	7.000 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 41378

TIC

TIC 366443426

Gaia DR2

Gaia DR2 600698184764497664

Gaia DR3

Gaia DR3 600698184764497664

System

HIP 41378

Percentile among Sub-Neptune cohort

Radius 2.540 R⊕ · percentile 43 / cohort 1978

Mass 7.000 M⊕ · percentile 40 / cohort 1978

Orbital period 62.06 d · percentile 89 / cohort 1946

Distance 106.29 pc · percentile 21 / cohort 1975

ESI 0.415 · percentile 55 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

62.060 days

Semi-major axis

— AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 62.06 Earth days (17.0% of a terrestrial year).

Eq. Temperature

605K

(332 °C)

Insolation (S⊕)

22.30

Earth = 1.00

Earth Similarity (ESI)

0.415

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

Discovery Paper

Primary reference

Howard et al. 2025

Instrument

HIRES Spectrometer

Publication

2025-06

Observation locale

Ground

Host System: HIP 41378

Spectral Class

F-type yellow-white

Effective Temperature

6,320 K — hotter than the Sun (5,778 K)

Estimated Age

4.28 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.273 R☉

Stellar Mass

1.160 M☉

Metallicity [Fe/H]

-0.10

Extended Stellar Properties

Surface gravity (log g)

4.294 dex

Stellar density

0.680 g/cm³

Systemic radial velocity

50.42 km/s

Rotational v·sin i

5.60 km/s

Activity index (log R'HK)

-4.780

Metallicity ratio

[Fe/H]

Distance

106.29 parsec

Light-years 346.67 ly

V-band magnitude

8.93 mag

Voyager-speed travel 6,113,489 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

9.380 mas

Total Proper Motion

48.143 mas/yr

PM Right Ascension

-48.14 mas/yr

PM Declination

0.06 mas/yr

Galactic Cartesian (pc)

x = -0.587 · y = 0.790 · z = 0.175

Equatorial (J2000)

RA 126.61583° · Dec 10.08037°

Galactic ℓ, b

214.526° · 25.646°

Ecliptic λ, β

126.459° · -8.845°

HTM-20 index

1036383337