Key parameters at a glance

A radius of 3.03 Earth radii
A mass of 9.43 Earth masses
Surface gravity around 1.03 g
An orbital period of 31.152 days
Semi-major axis 0.1916 AU
Distance from Earth 48.66 light-years
Earth Similarity Index 0.636
Travel time at Voyager 1 speed 858,174 years

HD 86728 b Planet Profile

Physical Specs

Radius

3.03 R⊕

Radius (Jupiter)

0.270 R♃

Mass

9.43 M⊕

Mass (Jupiter)

0.030 M♃

Density

1.86 g/cm³

Surface Gravity

1.03 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.636

HZ Position Unknown

Controversial No

Discovery

Year 2025

Method Radial Velocity

Facility Multiple Observatories

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#491of 1978

top 24.8%

This planet

3.03R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-498 b 3.03 R⊕ Kepler-245 d 3.03 R⊕ Kepler-162 c 3.03 R⊕

Metric	Earth	HD 86728 b	Jupiter
Radius (R⊕)	1.00	3.03	11.21
Mass (M⊕)	1.00	9.43	317.83
Density (g/cm³)	5.51	1.86	1.33
Surface Gravity (g)	1.00	1.03	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	9.430 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 86728

HIP

HIP 49081

TIC

TIC 172954294

Gaia DR2

Gaia DR2 746545172372256384

Gaia DR3

Gaia DR3 746545172372256384

System

HD 86728

Percentile among Sub-Neptune cohort

Radius 3.030 R⊕ · percentile 75 / cohort 1978

Mass 9.430 M⊕ · percentile 69 / cohort 1978

Orbital period 31.15 d · percentile 74 / cohort 1946

Distance 14.92 pc · percentile 3 / cohort 1975

ESI 0.636 · percentile 86 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

31.152 days

Semi-major axis

0.1916 AU

Eccentricity

0.067

Inclination

— °

Year Length

A year here lasts approximately 31.15 Earth days (8.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1916 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

1.970 m/s

Transit mid-time (BJD)

2,459,260.6900

Long. of periastron (ω)

92.00°

Angular separation (arcsec)

12.80000

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.636

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Gupta et al. 2025

Instrument

Multiple Instruments

Publication

2025-01

Observation locale

Ground

Discovery cohort

Planets confirmed in 2025 at Multiple Observatories (12 shown).

Gl 725 A b · Super-Earth HD 20794 f · Sub-Neptune GJ 3998 d · Sub-Neptune GJ 251 c · Super-Earth TOI-2015 c · Sub-Neptune Kepler-139 f · Neptune-like HD 73344 d · Gas Giant TOI-1472 c · Sub-Neptune TOI-6695 c · Gas Giant AT2021ueyL b · Gas Giant HIP 111909 b · Gas Giant TOI-6041 c · Gas Giant

Host System: HD 86728

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,610 K — cooler than the Sun (5,778 K)

Estimated Age

9.52 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.237 R☉

Stellar Mass

0.967 M☉

Metallicity [Fe/H]

0.20

Extended Stellar Properties

Surface gravity (log g)

4.250 dex

Stellar density

0.878 g/cm³

Systemic radial velocity

55.80 km/s

Rotational v·sin i

2.40 km/s

Activity index (log R'HK)

-5.060

Metallicity ratio

[Fe/H]

Distance

14.92 parsec

Light-years 48.66 ly

V-band magnitude

5.38 mag

Voyager-speed travel 858,174 yr

Multi-band Host Photometry — 7 bands

Astrometric Data

Parallax

66.996 mas

Total Proper Motion

681.334 mas/yr

PM Right Ascension

-528.81 mas/yr

PM Declination

-429.63 mas/yr

Galactic Cartesian (pc)

x = -0.737 · y = 0.421 · z = 0.529

Equatorial (J2000)

RA 150.25005° · Dec 31.92182°

Galactic ℓ, b

195.018° · 52.851°

Ecliptic λ, β

140.995° · 18.518°

HTM-20 index

-2146451210

Observation Record

Photometric series

RV measurements

Stellar spectra