Confirmed Exoplanet Discovered 2023

HD 15906 b

A sub-neptune orbiting the k-type orange HD 15906, located approximately 148.6 light-years from Earth.

Key parameters at a glance

  • A radius of 2.24 Earth radii
  • A mass of 5.65 Earth masses
  • Surface gravity around 1.13 g
  • An orbital period of 10.925 days
  • Semi-major axis 0.0900 AU
  • Equilibrium temperature 668 K (395 °C)
  • Distance from Earth 148.60 light-years
  • Earth Similarity Index 0.395
  • Travel time at Voyager 1 speed 2,620,623 years
  • Almost certainly tidally locked to its host star given the close orbit

1 sibling around HD 15906

HD 15906 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 15906 b this Sub-Neptune 2.24 5.65 10.925 668 2023
HD 15906 c Sub-Neptune 2.93 8.91 21.583 532 2023

HD 15906 b Planet Profile

Physical Specs

Radius
2.24 R⊕
Radius (Jupiter)
0.200 R♃
Mass
5.65 M⊕
Mass (Jupiter)
0.018 M♃
Density
2.76 g/cm³
Surface Gravity
1.13 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.395
HZ Position Inner
Controversial No

Discovery

Year 2023
Method Transit
Facility Transiting Exoplanet Survey Satellite (TESS)
Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#1607of 1978

top 81.2%

This planet

2.24R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Metric Earth HD 15906 b Jupiter
Radius (R⊕)1.002.2411.21
Mass (M⊕)1.005.65317.83
Density (g/cm³)5.512.761.33
Surface Gravity (g)1.001.132.53
Insolation (S⊕)1.0033.140.037

Star Catalogue Identifiers

HD

HD 15906

TIC

TIC 4646810

Gaia DR2

Gaia DR2 5175239363214344960

Gaia DR3

Gaia DR3 5175239363214344960

System

HD 15906

Percentile among Sub-Neptune cohort

Radius 2.240 R⊕ · percentile 18 / cohort 1978
Mass 5.650 M⊕ · percentile 18 / cohort 1978
Orbital period 10.92 d · percentile 38 / cohort 1946
Distance 45.56 pc · percentile 11 / cohort 1975
ESI 0.395 · percentile 51 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period
10.925 days
Semi-major axis
0.0900 AU
Eccentricity
0.110
Inclination
87.98 °

Year Length

A year here lasts approximately 10.92 Earth days (3.0% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0900 AU.

Transit Fingerprint

Depth

0.073 %

Duration

1.800 h

Impact parameter b

0.860

Rp / R★

0.027000

Transit midpoint (BJD)

2,458,416.3453

Photometric dip

Transit produces a flux drop of 729 ppm lasting ≈ 1.80 h.

Extended Orbital Architecture

Planet / star radius ratio

0.027000

Semi-major axis / stellar radius

25.350

Impact parameter (b)

0.860

Transit mid-time (BJD)

2,458,416.3453

Long. of periastron (ω)

160.50°

Angular separation (arcsec)

1.98000

Eq. Temperature

668K

(395 °C)

Insolation (S⊕)

33.14

Earth = 1.00

Earth Similarity (ESI)

0.395

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.

Discovery Paper

Primary reference

Tuson et al. 2023

Instrument

TESS CCD Array

Publication

2023-08

Observation locale

Space

Host System: HD 15906

Spectral Class

K-type orange

Effective Temperature

4,757 K — cooler than the Sun (5,778 K)

Estimated Age

Stellar Radius

0.762 R☉

Stellar Mass

0.790 M☉

Metallicity [Fe/H]

0.02

Extended Stellar Properties

Surface gravity (log g)

4.490 dex

Stellar density

2.583 g/cm³

Systemic radial velocity

-3.64 km/s

Rotational v·sin i

2.70 km/s

Activity index (log R'HK)

-4.694

Metallicity ratio

[Fe/H]

Distance
45.56 parsec
Light-years 148.60 ly
V-band magnitude
9.78 mag
Voyager-speed travel 2,620,623 yr

Multi-band Host Photometry — 11 bands

7.310.710.73B9.78V9.48Gaia8.87TESS8.04J7.56H7.46K7.35W17.46W27.42W37.34W4

Astrometric Data

Parallax

21.919 mas

Total Proper Motion

196.028 mas/yr

PM Right Ascension

-173.03 mas/yr

PM Declination

-92.13 mas/yr

Galactic Cartesian (pc)

x = 0.772 · y = 0.609 · z = -0.180

Equatorial (J2000)

RA 38.27125° · Dec -10.35218°

Galactic ℓ, b

182.778° · -60.778°

Ecliptic λ, β

32.260° · -24.031°

HTM-20 index

747272008

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