Key parameters at a glance

A radius of 14.30 Earth radii
A mass of 139.85 Earth masses
Surface gravity around 0.68 g
An orbital period of 439.300 days
Semi-major axis 1.1100 AU
Distance from Earth 178.70 light-years
Earth Similarity Index 0.244
Travel time at Voyager 1 speed 3,151,395 years

HD 99109 b Planet Profile

Physical Specs

Radius

14.30 R⊕

Radius (Jupiter)

1.280 R♃

Mass

139.85 M⊕

Mass (Jupiter)

0.440 M♃

Density

0.26 g/cm³

Surface Gravity

0.68 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.244

HZ Position Unknown

Controversial No

Discovery

Year 2005

Method Radial Velocity

Facility W. M. Keck Observatory

Telescope 10 m Keck I Telescope

Size rank in cohort

Rank by radius

#301of 1771

top 16.9%

This planet

14.30R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

HIP 65407 b 14.30 R⊕ HD 30669 b 14.30 R⊕ HD 45652 b 14.30 R⊕

Metric	Earth	HD 99109 b	Jupiter
Radius (R⊕)	1.00	14.30	11.21
Mass (M⊕)	1.00	139.85	317.83
Density (g/cm³)	5.51	0.26	1.33
Surface Gravity (g)	1.00	0.68	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	139.845 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 99109

HIP

HIP 55664

TIC

TIC 38158652

Gaia DR2

Gaia DR2 3796826582305099520

Gaia DR3

Gaia DR3 3796826582305099520

System

HD 99109

Percentile among Gas Giant cohort

Radius 14.300 R⊕ · percentile 82 / cohort 1771

Mass 139.845 M⊕ · percentile 11 / cohort 1747

Orbital period 439.30 d · percentile 66 / cohort 1533

Distance 54.79 pc · percentile 22 / cohort 1759

ESI 0.244 · percentile 42 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

439.300 days

Semi-major axis

1.1100 AU

Eccentricity

0.090

Inclination

— °

Year Length

A year here lasts about 1.20 Earth years on a nearly circular orbit at a mean orbital distance of 1.1100 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

14.100 m/s

Transit mid-time (BJD)

2,451,991.0000

Long. of periastron (ω)

6.00°

Angular separation (arcsec)

20.30000

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.244

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Butler et al. 2006

Instrument

HIRES Spectrometer

Publication

2006-07

Observation locale

Ground

Discovery cohort

Planets confirmed in 2005 at W. M. Keck Observatory (12 shown).

GJ 876 d · Sub-Neptune HD 190360 c · Neptune-like HIP 14810 b · Gas Giant HD 128311 c · Gas Giant HD 66428 b · Gas Giant HD 50499 b · Gas Giant HD 107148 b · Neptune-like HD 108874 c · Gas Giant HD 109749 b · Gas Giant HD 37124 d · Gas Giant HD 11964 b · Gas Giant HD 164922 b · Gas Giant

Host System: HD 99109

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,282 K — cooler than the Sun (5,778 K)

Estimated Age

1.00 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.980 R☉

Stellar Mass

0.760 M☉

Metallicity [Fe/H]

0.35

Extended Stellar Properties

Surface gravity (log g)

4.340 dex

Stellar density

1.315 g/cm³

Systemic radial velocity

33.34 km/s

Rotational v·sin i

1.86 km/s

Activity index (log R'HK)

-5.060

Metallicity ratio

[Fe/H]

Distance

54.79 parsec

Light-years 178.70 ly

V-band magnitude

9.10 mag

Voyager-speed travel 3,151,395 yr

Multi-band Host Photometry — 12 bands

Astrometric Data

Parallax

18.223 mas

Total Proper Motion

239.755 mas/yr

PM Right Ascension

-178.78 mas/yr

PM Declination

-159.75 mas/yr

Galactic Cartesian (pc)

x = -0.988 · y = 0.155 · z = -0.027

Equatorial (J2000)

RA 171.07156° · Dec -1.52976°

Galactic ℓ, b

263.238° · 54.483°

Ecliptic λ, β

172.398° · -4.945°

HTM-20 index

369088326

Observation Record

Photometric series

RV measurements

Stellar spectra

Archive notes