Key parameters at a glance

A radius of 0.75 Earth radii
A mass of 0.55 Earth masses
Surface gravity around 0.98 g
An orbital period of 3.977 days
Semi-major axis 0.0430 AU
Equilibrium temperature 909 K (636 °C)
Distance from Earth 127.31 light-years
Earth Similarity Index 0.333
Travel time at Voyager 1 speed 2,245,148 years
Almost certainly tidally locked to its host star given the close orbit

4 siblings around HD 23472

HD 23472 d shares its host star with 4 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
HD 23472 d this	Rocky Terrestrial	0.75	0.55	3.977	909	2022
HD 23472 e	Rocky Terrestrial	0.82	0.72	7.908	723	2022
HD 23472 f	Rocky Terrestrial	1.14	0.77	12.162	630	2022
HD 23472 b	Sub-Neptune	2.00	8.32	17.667	543	2019
HD 23472 c	Super-Earth	1.87	3.41	29.797	467	2019

HD 23472 d Planet Profile

Physical Specs

Radius

0.75 R⊕

Radius (Jupiter)

0.067 R♃

Mass

0.55 M⊕

Mass (Jupiter)

0.002 M♃

Density

7.50 g/cm³

Surface Gravity

0.98 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.333

HZ Position Inner

Controversial No

Discovery

Year 2022

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#508of 570

top 88.9%

This planet

0.75R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-378 b 0.75 R⊕ Kepler-1563 b 0.75 R⊕ Kepler-1864 b 0.75 R⊕

Metric	Earth	HD 23472 d	Jupiter
Radius (R⊕)	1.00	0.75	11.21
Mass (M⊕)	1.00	0.55	317.83
Density (g/cm³)	5.51	7.50	1.33
Surface Gravity (g)	1.00	0.98	2.53
Insolation (S⊕)	1.00	117.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	0.550 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

HD 23472

HIP

HIP 17264

TIC

TIC 425997655

Gaia DR2

Gaia DR2 4674216245427964416

Gaia DR3

Gaia DR3 4674216245427964416

System

HD 23472

Percentile among Rocky Terrestrial cohort

Radius 0.750 R⊕ · percentile 11 / cohort 570

Mass 0.550 M⊕ · percentile 17 / cohort 570

Orbital period 3.98 d · percentile 44 / cohort 567

Distance 39.03 pc · percentile 16 / cohort 566

ESI 0.333 · percentile 47 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

3.977 days

Semi-major axis

0.0430 AU

Eccentricity

0.070

Inclination

87.95 °

Year Length

A year here lasts approximately 3.98 Earth days (1.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0430 AU.

Transit Fingerprint

Depth

0.014 %

Duration

1.990 h

Impact parameter b

0.470

Rp / R★

0.009752

Transit midpoint (BJD)

2,458,357.8398

Photometric dip

Transit produces a flux drop of 142 ppm lasting ≈ 1.99 h.

Extended Orbital Architecture

Planet / star radius ratio

0.009752

Semi-major axis / stellar radius

13.290

Impact parameter (b)

0.470

RV semi-amplitude (K)

0.290 m/s

Transit mid-time (BJD)

2,458,357.8398

Long. of periastron (ω)

19.00°

Angular separation (arcsec)

1.10000

Eq. Temperature

909K

(636 °C)

Insolation (S⊕)

117.00

Earth = 1.00

Earth Similarity (ESI)

0.333

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Barros et al. 2022

Instrument

TESS CCD Array

Publication

2022-09

Observation locale

Space

Discovery cohort

Planets confirmed in 2022 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-1452 b · Super-Earth TOI-712 d · Sub-Neptune TOI-1468 c · Sub-Neptune TOI-2136 b · Sub-Neptune LTT 1445 A c · Rocky Terrestrial TOI-712 c · Sub-Neptune LP 890-9 b · Super-Earth TOI-2081 b · Sub-Neptune GJ 3929 b · Rocky Terrestrial HD 260655 c · Super-Earth HD 73583 c · Sub-Neptune TOI-1759 b · Sub-Neptune

Host System: HD 23472

Spectral Class

K-type orange

Effective Temperature

4,684 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.710 R☉

Stellar Mass

0.670 M☉

Metallicity [Fe/H]

-0.20

Extended Stellar Properties

Surface gravity (log g)

4.530 dex

Stellar density

2.707 g/cm³

Systemic radial velocity

34.55 km/s

Rotational v·sin i

1.45 km/s

Rotation period

40.10 days

Activity index (log R'HK)

-4.997

Metallicity ratio

[Fe/H]

Distance

39.03 parsec

Light-years 127.31 ly

V-band magnitude

9.73 mag

Voyager-speed travel 2,245,148 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

25.590 mas

Total Proper Motion

111.577 mas/yr

PM Right Ascension

-102.57 mas/yr

PM Declination

-43.92 mas/yr

Galactic Cartesian (pc)

x = 0.259 · y = 0.377 · z = -0.889

Equatorial (J2000)

RA 55.45903° · Dec -62.76727°

Galactic ℓ, b

277.027° · -44.848°

Ecliptic λ, β

358.263° · -74.955°

HTM-20 index

730030629