Key parameters at a glance

A radius of 4.94 Earth radii
A mass of 21.60 Earth masses
Surface gravity around 0.89 g
An orbital period of 282.200 days
Semi-major axis 0.8270 AU
Distance from Earth 56.97 light-years
Earth Similarity Index 0.480
Travel time at Voyager 1 speed 1,004,666 years

2 siblings around rho CrB

rho CrB d shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
rho CrB e	Super-Earth	1.77	3.79	12.949	—	2023
rho CrB c	Neptune-like	5.78	28.20	102.190	448	2016
rho CrB d this	Neptune-like	4.94	21.60	282.200	—	2023

rho CrB d Planet Profile

Physical Specs

Radius

4.94 R⊕

Radius (Jupiter)

0.440 R♃

Mass

21.60 M⊕

Mass (Jupiter)

0.068 M♃

Density

0.99 g/cm³

Surface Gravity

0.89 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.480

HZ Position Unknown

Controversial No

Discovery

Year 2023

Method Radial Velocity

Facility Lowell Observatory

Telescope 4.3 m Lowell Discovery Telescope

Size rank in cohort

Rank by radius

#390of 574

top 67.8%

This planet

4.94R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

HIP 19976 b 4.94 R⊕ HD 147379 b 4.94 R⊕ TOI-329 b 4.94 R⊕

Metric	Earth	rho CrB d	Jupiter
Radius (R⊕)	1.00	4.94	11.21
Mass (M⊕)	1.00	21.60	317.83
Density (g/cm³)	5.51	0.99	1.33
Surface Gravity (g)	1.00	0.89	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	21.600 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 143761

HIP

HIP 78459

TIC

TIC 458494003

Gaia DR2

Gaia DR2 1323427759184545536

Gaia DR3

Gaia DR3 1323427759184545536

System

rho CrB

Percentile among Neptune-like cohort

Radius 4.940 R⊕ · percentile 32 / cohort 574

Mass 21.600 M⊕ · percentile 34 / cohort 574

Orbital period 282.20 d · percentile 92 / cohort 524

Distance 17.47 pc · percentile 4 / cohort 572

ESI 0.480 · percentile 86 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

282.200 days

Semi-major axis

0.8270 AU

Eccentricity

0.000

Inclination

— °

Year Length

A year here lasts approximately 282.20 Earth days (77.3% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.8270 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

2.200 m/s

Transit mid-time (BJD)

2,455,583.0000

Long. of periastron (ω)

0.00°

Angular separation (arcsec)

47.30000

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.480

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Brewer et al. 2023

Instrument

EXPRES spectrograph

Publication

2023-08

Observation locale

Ground

Host System: rho CrB

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,817 K — hotter than the Sun (5,778 K)

Estimated Age

10.20 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.340 R☉

Stellar Mass

0.950 M☉

Metallicity [Fe/H]

-0.20

Extended Stellar Properties

Surface gravity (log g)

4.250 dex

Stellar density

0.646 g/cm³

Systemic radial velocity

17.80 km/s

Rotational v·sin i

0.80 km/s

Activity index (log R'HK)

-5.080

Metallicity ratio

[Fe/H]

Distance

17.47 parsec

Light-years 56.97 ly

V-band magnitude

5.41 mag

Voyager-speed travel 1,004,666 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

57.222 mas

Total Proper Motion

797.522 mas/yr

PM Right Ascension

-198.54 mas/yr

PM Declination

-772.42 mas/yr

Galactic Cartesian (pc)

x = -0.415 · y = -0.726 · z = 0.549

Equatorial (J2000)

RA 240.26006° · Dec 33.30019°

Galactic ℓ, b

53.484° · 48.924°

Ecliptic λ, β

227.177° · 52.410°

HTM-20 index

1280940784

Observation Record

Photometric series

RV measurements

Stellar spectra

Archive notes