Key parameters at a glance

A radius of 12.60 Earth radii
A mass of 2,552.17 Earth masses
Surface gravity around 16.08 g
An orbital period of 71.484 days
Semi-major axis 0.3400 AU
Distance from Earth 133.63 light-years
Earth Similarity Index 0.413
Travel time at Voyager 1 speed 2,356,652 years

HD 178911 B b Planet Profile

Physical Specs

Radius

12.60 R⊕

Radius (Jupiter)

1.120 R♃

Mass

2,552.17 M⊕

Mass (Jupiter)

8.030 M♃

Density

7.01 g/cm³

Surface Gravity

16.08 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.413

HZ Position Unknown

Controversial No

Discovery

Year 2001

Method Radial Velocity

Facility W. M. Keck Observatory

Telescope 10 m Keck I Telescope

Size rank in cohort

Rank by radius

#1179of 1771

top 66.5%

This planet

12.60R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Kepler-419 c 12.60 R⊕ 2MASS J04414489+2301513 b 12.60 R⊕ HD 47536 b 12.60 R⊕

Metric	Earth	HD 178911 B b	Jupiter
Radius (R⊕)	1.00	12.60	11.21
Mass (M⊕)	1.00	2,552.17	317.83
Density (g/cm³)	5.51	7.01	1.33
Surface Gravity (g)	1.00	16.08	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Minimum mass (M sin i)	2,552.175 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 178911 B

HIP

HIP 94075

TIC

TIC 42812945

Gaia DR2

Gaia DR2 2044341077844180736

Gaia DR3

Gaia DR3 2044341077844180736

System

HD 178911

Percentile among Gas Giant cohort

Radius 12.600 R⊕ · percentile 31 / cohort 1771

Mass 2,552.175 M⊕ · percentile 84 / cohort 1747

Orbital period 71.48 d · percentile 52 / cohort 1533

Distance 40.97 pc · percentile 14 / cohort 1759

ESI 0.413 · percentile 89 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

71.484 days

Semi-major axis

0.3400 AU

Eccentricity

0.110

Inclination

— °

Year Length

A year here lasts approximately 71.48 Earth days (19.6% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.3400 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

343.300 m/s

Transit mid-time (BJD)

2,450,292.6800

Long. of periastron (ω)

-13.90°

Angular separation (arcsec)

8.30000

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.413

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Zucker et al. 2002

Instrument

HIRES Spectrometer

Publication

2002-03

Observation locale

Ground

Discovery cohort

Planets confirmed in 2001 at W. M. Keck Observatory (3 shown).

HD 4203 b · Gas Giant HD 114783 b · Gas Giant HD 4208 b · Gas Giant

Host System: HD 178911 B

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,588 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

1.080 R☉

Stellar Mass

1.240 M☉

Metallicity [Fe/H]

0.24

Extended Stellar Properties

Surface gravity (log g)

4.460 dex

Stellar density

1.286 g/cm³

Systemic radial velocity

-40.41 km/s

Rotational v·sin i

1.90 km/s

Activity index (log R'HK)

-4.980

Metallicity ratio

[Fe/H]

Distance

40.97 parsec

Light-years 133.63 ly

V-band magnitude

7.97 mag

Voyager-speed travel 2,356,652 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

24.378 mas

Total Proper Motion

204.074 mas/yr

PM Right Ascension

57.18 mas/yr

PM Declination

195.90 mas/yr

Galactic Cartesian (pc)

x = 0.244 · y = -0.786 · z = 0.568

Equatorial (J2000)

RA 287.26321° · Dec 34.60070°

Galactic ℓ, b

65.992° · 11.694°

Ecliptic λ, β

296.248° · 56.477°

HTM-20 index

990087770

Observation Record

Photometric series

RV measurements

Stellar spectra

Archive notes