Key parameters at a glance

A radius of 13.51 Earth radii
A mass of 97.57 Earth masses
Surface gravity around 0.53 g
An orbital period of 4.218 days
Semi-major axis 0.0504 AU
Equilibrium temperature 1,168 K (895 °C)
Distance from Earth 1,435.38 light-years
Earth Similarity Index 0.093
Travel time at Voyager 1 speed 25,312,866 years

HAT-P-51 b Planet Profile

Physical Specs

Radius

13.51 R⊕

Radius (Jupiter)

1.205 R♃

Mass

97.57 M⊕

Mass (Jupiter)

0.307 M♃

Density

0.22 g/cm³

Surface Gravity

0.53 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.093

HZ Position Inner

Controversial No

Discovery

Year 2015

Method Transit

Facility HATNet

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#670of 1771

top 37.8%

This planet

13.51R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

NGTS-10 b 13.51 R⊕ HD 45350 b 13.50 R⊕ HD 27442 b 13.50 R⊕

Metric	Earth	HAT-P-51 b	Jupiter
Radius (R⊕)	1.00	13.51	11.21
Mass (M⊕)	1.00	97.57	317.83
Density (g/cm³)	5.51	0.22	1.33
Surface Gravity (g)	1.00	0.53	2.53
Insolation (S⊕)	1.00	310.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	97.573 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 61205803

Gaia DR2

Gaia DR2 316706322857704960

Gaia DR3

Gaia DR3 316706322857704960

System

HAT-P-51

Percentile among Gas Giant cohort

Radius 13.507 R⊕ · percentile 62 / cohort 1771

Mass 97.573 M⊕ · percentile 5 / cohort 1747

Orbital period 4.22 d · percentile 31 / cohort 1533

Distance 440.09 pc · percentile 72 / cohort 1759

ESI 0.093 · percentile 24 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

4.218 days

Semi-major axis

0.0504 AU

Eccentricity

0.070

Inclination

89.28 °

Year Length

A year here lasts approximately 4.22 Earth days (1.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0504 AU.

Transit Fingerprint

Depth

1.853 %

Duration

3.367 h

Impact parameter b

0.277

Rp / R★

0.125300

Transit midpoint (BJD)

2,458,349.5312

Photometric dip

Transit produces a flux drop of 18,528 ppm lasting ≈ 3.37 h.

Extended Orbital Architecture

Planet / star radius ratio

0.125300

Semi-major axis / stellar radius

10.860

Impact parameter (b)

0.277

RV semi-amplitude (K)

39.700 m/s

Transit mid-time (BJD)

2,458,349.5312

Angular separation (arcsec)

0.11500

Eq. Temperature

1,168K

(895 °C)

Insolation (S⊕)

310.00

Earth = 1.00

Earth Similarity (ESI)

0.093

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.

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

Hartman et al. 2015

Instrument

Multiple Instruments

Publication

2015-12

Observation locale

Ground

Discovery cohort

Planets confirmed in 2015 at HATNet (7 shown).

HAT-P-54 b · Gas Giant HAT-P-52 b · Gas Giant HAT-P-55 b · Gas Giant HAT-P-53 b · Gas Giant HAT-P-50 b · Gas Giant HAT-P-56 b · Gas Giant HAT-P-57 b · Gas Giant

Host System: HAT-P-51

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,453 K — cooler than the Sun (5,778 K)

Estimated Age

8.10 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

0.995 R☉

Stellar Mass

0.961 M☉

Metallicity [Fe/H]

0.30

Extended Stellar Properties

Surface gravity (log g)

4.426 dex

Stellar density

1.380 g/cm³

Systemic radial velocity

-27.56 km/s

Rotational v·sin i

1.70 km/s

Metallicity ratio

[Fe/H]

Distance

440.09 parsec

Light-years 1,435.38 ly

V-band magnitude

13.51 mag

Voyager-speed travel 25,312,866 yr

Multi-band Host Photometry — 15 bands

Astrometric Data

Parallax

2.244 mas

Total Proper Motion

18.995 mas/yr

PM Right Ascension

-9.18 mas/yr

PM Declination

-16.63 mas/yr

Galactic Cartesian (pc)

x = 0.784 · y = 0.302 · z = 0.542

Equatorial (J2000)

RA 21.06513° · Dec 32.81070°

Galactic ℓ, b

130.858° · -29.555°

Ecliptic λ, β

32.133° · 22.147°

HTM-20 index

1441749743