Key parameters at a glance

A radius of 5.44 Earth radii
A mass of 25.43 Earth masses
Surface gravity around 0.86 g
An orbital period of 17.117 days
Semi-major axis 0.1296 AU
Distance from Earth 52.21 light-years
Earth Similarity Index 0.452
Travel time at Voyager 1 speed 920,679 years

Context from the literature

Gliese 777 Ac, also known as HD 190360 c, is an extrasolar planet approximately 52 light-years away in the constellation of Cygnus. The planet was discovered orbiting the primary star of the Gliese 777 system in 2005 using the radial velocity method and confirmed in 2009. The planet was once called the "smallest extrasolar planet discovered", but this is currently no longer the case. With a mass just 25 times that of the Earth, the planet is likely a "hot Neptune" planet, a small Jovian planet, or possibly a large terrestrial planet.

Excerpted from Wikipedia · full article

1 sibling around HD 190360

HD 190360 c 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 190360 c this	Neptune-like	5.44	25.43	17.117	—	2005
HD 190360 b	Gas Giant	13.50	533.95	2,892.000	150	2003

HD 190360 c Planet Profile

Physical Specs

Radius

5.44 R⊕

Radius (Jupiter)

0.485 R♃

Mass

25.43 M⊕

Mass (Jupiter)

0.080 M♃

Density

0.87 g/cm³

Surface Gravity

0.86 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.452

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

#322of 574

top 55.9%

This planet

5.44R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

HD 105618 b 5.44 R⊕ HD 99492 b 5.44 R⊕ KOI-1783.02 5.44 R⊕

Metric	Earth	HD 190360 c	Jupiter
Radius (R⊕)	1.00	5.44	11.21
Mass (M⊕)	1.00	25.43	317.83
Density (g/cm³)	5.51	0.87	1.33
Surface Gravity (g)	1.00	0.86	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	25.426 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	21.453 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 190360

HIP

HIP 98767

TIC

TIC 105999792

Gaia DR2

Gaia DR2 2029433521248546304

Gaia DR3

Gaia DR3 2029433521248546304

System

HD 190360

Percentile among Neptune-like cohort

Radius 5.440 R⊕ · percentile 43 / cohort 574

Mass 25.426 M⊕ · percentile 43 / cohort 574

Orbital period 17.12 d · percentile 48 / cohort 524

Distance 16.01 pc · percentile 4 / cohort 572

ESI 0.452 · percentile 81 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

17.117 days

Semi-major axis

0.1296 AU

Eccentricity

0.165

Inclination

90.00 °

Year Length

A year here lasts approximately 17.12 Earth days (4.7% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.1296 AU.

Extended Orbital Architecture

RV semi-amplitude (K)

5.430 m/s

Transit mid-time (BJD)

2,455,198.6100

Long. of periastron (ω)

323.40°

Angular separation (arcsec)

8.10000

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.452

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Vogt et al. 2005

Instrument

HIRES Spectrometer

Publication

2005-10

Observation locale

Ground

Discovery cohort

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

GJ 876 d · Sub-Neptune 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 99109 b · Gas Giant HD 164922 b · Gas Giant

Host System: HD 190360

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,552 K — cooler than the Sun (5,778 K)

Estimated Age

11.30 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.201 R☉

Stellar Mass

0.991 M☉

Metallicity [Fe/H]

0.25

Extended Stellar Properties

Surface gravity (log g)

4.298 dex

Stellar density

0.867 g/cm³

Systemic radial velocity

-45.35 km/s

Rotational v·sin i

2.20 km/s

Activity index (log R'HK)

-5.090

Metallicity ratio

[Fe/H]

Distance

16.01 parsec

Light-years 52.21 ly

V-band magnitude

5.74 mag

Voyager-speed travel 920,679 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

62.444 mas

Total Proper Motion

862.142 mas/yr

PM Right Ascension

683.34 mas/yr

PM Declination

-525.68 mas/yr

Galactic Cartesian (pc)

x = 0.445 · y = -0.744 · z = 0.498

Equatorial (J2000)

RA 300.90925° · Dec 29.89454°

Galactic ℓ, b

67.411° · -0.676°

Ecliptic λ, β

312.602° · 48.864°

HTM-20 index

-1211378946

Observation Record

Photometric series

RV measurements

Stellar spectra

Archive notes

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