Key parameters at a glance

A radius of 2.80 Earth radii
A mass of 8.23 Earth masses
Surface gravity around 1.05 g
An orbital period of 22.679 days
Semi-major axis 0.1455 AU
Distance from Earth 108.46 light-years
Earth Similarity Index 0.664
Travel time at Voyager 1 speed 1,912,748 years

1 sibling around HD 21693

HD 21693 b shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
HD 21693 b this	Sub-Neptune	2.80	8.23	22.679	—	2019
HD 21693 c	Neptune-like	4.34	17.37	53.736	—	2019

HD 21693 b Planet Profile

Physical Specs

Radius

2.80 R⊕

Radius (Jupiter)

0.250 R♃

Mass

8.23 M⊕

Mass (Jupiter)

0.026 M♃

Density

2.06 g/cm³

Surface Gravity

1.05 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.664

HZ Position Unknown

Controversial No

Discovery

Year 2019

Method Radial Velocity

Facility La Silla Observatory

Telescope 3.6 m ESO Telescope

Size rank in cohort

Rank by radius

#742of 1978

top 37.5%

This planet

2.80R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-694 b 2.80 R⊕ Kepler-276 d 2.80 R⊕ Kepler-350 d 2.80 R⊕

Metric	Earth	HD 21693 b	Jupiter
Radius (R⊕)	1.00	2.80	11.21
Mass (M⊕)	1.00	8.23	317.83
Density (g/cm³)	5.51	2.06	1.33
Surface Gravity (g)	1.00	1.05	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	8.230 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 21693

HIP

HIP 16085

TIC

TIC 197792776

Gaia DR2

Gaia DR2 4729947569262040960

Gaia DR3

Gaia DR3 4729947569262040960

System

HD 21693

Percentile among Sub-Neptune cohort

Radius 2.800 R⊕ · percentile 62 / cohort 1978

Mass 8.230 M⊕ · percentile 57 / cohort 1978

Orbital period 22.68 d · percentile 66 / cohort 1946

Distance 33.26 pc · percentile 8 / cohort 1975

ESI 0.664 · percentile 89 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

22.679 days

Semi-major axis

0.1455 AU

Eccentricity

0.120

Inclination

— °

Year Length

A year here lasts approximately 22.68 Earth days (6.2% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1455 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.664

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Udry et al. 2019

Instrument

HARPS Spectrograph

Publication

2019-02

Observation locale

Ground

Discovery cohort

Planets confirmed in 2019 at La Silla Observatory (12 shown).

HD 20781 b · Rocky Terrestrial HD 20781 c · Sub-Neptune HD 45184 c · Sub-Neptune HD 134060 b · Sub-Neptune HD 31527 b · Sub-Neptune HD 20781 d · Sub-Neptune HD 20003 b · Sub-Neptune HD 31527 d · Sub-Neptune HD 45184 b · Sub-Neptune HD 51608 b · Sub-Neptune HD 136352 d · Sub-Neptune HD 20781 e · Sub-Neptune

Host System: HD 21693

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,430 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.914 R☉

Stellar Mass

0.800 M☉

Metallicity [Fe/H]

0.00

Extended Stellar Properties

Surface gravity (log g)

4.370 dex

Stellar density

1.703 g/cm³

Systemic radial velocity

39.10 km/s

Rotational v·sin i

1.60 km/s

Rotation period

35.20 days

Metallicity ratio

[Fe/H]

Distance

33.26 parsec

Light-years 108.46 ly

V-band magnitude

7.95 mag

Voyager-speed travel 1,912,748 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

30.042 mas

Total Proper Motion

266.058 mas/yr

PM Right Ascension

248.65 mas/yr

PM Declination

94.65 mas/yr

Galactic Cartesian (pc)

x = 0.325 · y = 0.413 · z = -0.851

Equatorial (J2000)

RA 51.80405° · Dec -58.32327°

Galactic ℓ, b

272.908° · -48.724°

Ecliptic λ, β

7.040° · -70.902°

HTM-20 index

1230760665