Confirmed Exoplanet Discovered 2019

HD 23472 b

A sub-neptune orbiting the k-type orange HD 23472, located approximately 127.3 light-years from Earth.

Key parameters at a glance

  • A radius of 2.00 Earth radii
  • A mass of 8.32 Earth masses
  • Surface gravity around 2.08 g
  • An orbital period of 17.667 days
  • Semi-major axis 0.1162 AU
  • Equilibrium temperature 543 K (270 °C)
  • Distance from Earth 127.31 light-years
  • Earth Similarity Index 0.518
  • 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 b 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 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 this 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 b Planet Profile

Physical Specs

Radius
2.00 R⊕
Radius (Jupiter)
0.178 R♃
Mass
8.32 M⊕
Mass (Jupiter)
0.026 M♃
Density
6.15 g/cm³
Surface Gravity
2.08 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.518
HZ Position Inner
Controversial No

Discovery

Year 2019
Method Transit
Facility Transiting Exoplanet Survey Satellite (TESS)
Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#1955of 1978

top 98.8%

This planet

2.00R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-32 c 2.00 R⊕ Kepler-238 f 2.00 R⊕ Kepler-242 c 2.00 R⊕
Metric Earth HD 23472 b Jupiter
Radius (R⊕)1.002.0011.21
Mass (M⊕)1.008.32317.83
Density (g/cm³)5.516.151.33
Surface Gravity (g)1.002.082.53
Insolation (S⊕)1.0016.000.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 8.320 M⊕ Direct mass measurement (not derived).

Star Catalogue Identifiers

HD

HD 23472

HIP

HIP 17264

TIC

TIC 425997655

Gaia DR2

Gaia DR2 4674216245427964416

Gaia DR3

Gaia DR3 4674216245427964416

System

HD 23472

Percentile among Sub-Neptune cohort

Radius 2.000 R⊕ · percentile 0 / cohort 1978
Mass 8.320 M⊕ · percentile 58 / cohort 1978
Orbital period 17.67 d · percentile 58 / cohort 1946
Distance 39.03 pc · percentile 10 / cohort 1975
ESI 0.518 · percentile 73 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period
17.667 days
Semi-major axis
0.1162 AU
Eccentricity
0.072
Inclination
88.93 °

Year Length

A year here lasts approximately 17.67 Earth days (4.8% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1162 AU.

Transit Fingerprint

Depth

0.075 %

Duration

2.670 h

Impact parameter b

0.690

Rp / R★

0.025970

Transit midpoint (BJD)

2,458,360.6641

Photometric dip

Transit produces a flux drop of 755 ppm lasting ≈ 2.67 h.

Extended Orbital Architecture

Planet / star radius ratio

0.025970

Semi-major axis / stellar radius

37.100

Impact parameter (b)

0.690

RV semi-amplitude (K)

2.680 m/s

Transit mid-time (BJD)

2,458,360.6641

Long. of periastron (ω)

114.00°

Angular separation (arcsec)

2.98000

Eq. Temperature

543K

(270 °C)

Insolation (S⊕)

16.00

Earth = 1.00

Earth Similarity (ESI)

0.518

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

Trifonov et al. 2019

Instrument

TESS CCD Array

Publication

2019-02

Observation locale

Space

Discovery cohort

Planets confirmed in 2019 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

LP 791-18 c · Sub-Neptune LTT 1445 A b · Super-Earth TOI-270 d · Sub-Neptune L 98-59 d · Super-Earth GJ 357 b · Rocky Terrestrial GJ 143 b · Sub-Neptune HD 23472 c · Super-Earth L 98-59 c · Super-Earth LP 791-18 b · Rocky Terrestrial TOI-270 c · Sub-Neptune TOI-270 b · Super-Earth L 98-59 b · Rocky Terrestrial

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

7.010.710.69B9.73V9.38Gaia8.75TESS7.87J7.35H7.21K7.00W17.22W27.18W37.04W4

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

Similar Worlds

Kepler-801 b

Sub-Neptune · K-type orange

Radius 2.00 R⊕ · 1,436.5 ly

Kepler-968 b

Sub-Neptune · K-type orange

Radius 2.00 R⊕ · 946.9 ly

Kepler-261 c

Sub-Neptune · K-type orange

Radius 2.00 R⊕ · 1,035.5 ly

Kepler-242 c

Sub-Neptune · K-type orange

Radius 2.00 R⊕ · 1,957.7 ly

K2-381 c

Sub-Neptune · K-type orange

Radius 2.00 R⊕ · 475.2 ly

K2-101 b

Sub-Neptune · K-type orange

Radius 2.00 R⊕ · 614.2 ly

Explore Related Categories

Sub-Neptune Planets Transit Discoveries Transiting Exoplanet Survey Satellite (TESS) Mission K-type orange Hosts