Key parameters at a glance

A radius of 10.08 Earth radii
A mass of 335.94 Earth masses
Surface gravity around 3.31 g
An orbital period of 1.902 days
Semi-major axis 0.0301 AU
Equilibrium temperature 1,505 K (1232 °C)
Distance from Earth 1,105.15 light-years
Earth Similarity Index 0.107
Travel time at Voyager 1 speed 19,489,266 years

HAT-P-61 b Planet Profile

Physical Specs

Radius

10.08 R⊕

Radius (Jupiter)

0.899 R♃

Mass

335.94 M⊕

Mass (Jupiter)

1.057 M♃

Density

1.80 g/cm³

Surface Gravity

3.31 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.107

HZ Position Inner

Controversial No

Discovery

Year 2021

Method Transit

Facility HATNet

Telescope Multiple Telescopes

Size rank in cohort

Rank by radius

#1768of 1771

top 99.8%

This planet

10.08R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

TOI-2337 b 10.09 R⊕ WASP-145 A b 10.09 R⊕ CoRoT-29 b 10.09 R⊕

Metric	Earth	HAT-P-61 b	Jupiter
Radius (R⊕)	1.00	10.08	11.21
Mass (M⊕)	1.00	335.94	317.83
Density (g/cm³)	5.51	1.80	1.33
Surface Gravity (g)	1.00	3.31	2.53
Insolation (S⊕)	1.00	849.50	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	335.945 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 259506033

Gaia DR2

Gaia DR2 256580182331399296

Gaia DR3

Gaia DR3 256580182331399296

System

HAT-P-61

Percentile among Gas Giant cohort

Radius 10.077 R⊕ · percentile 0 / cohort 1771

Mass 335.945 M⊕ · percentile 36 / cohort 1747

Orbital period 1.90 d · percentile 6 / cohort 1533

Distance 338.84 pc · percentile 64 / cohort 1759

ESI 0.107 · percentile 28 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

1.902 days

Semi-major axis

0.0301 AU

Eccentricity

0.113

Inclination

83.62 °

Year Length

A year here lasts approximately 1.90 Earth days (0.5% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0301 AU.

Transit Fingerprint

Depth

1.072 %

Duration

1.658 h

Impact parameter b

0.767

Rp / R★

0.098400

Transit midpoint (BJD)

2,457,851.2112

Photometric dip

Transit produces a flux drop of 10,718 ppm lasting ≈ 1.66 h.

Extended Orbital Architecture

Planet / star radius ratio

0.098400

Semi-major axis / stellar radius

6.900

Impact parameter (b)

0.767

RV semi-amplitude (K)

173.000 m/s

Transit mid-time (BJD)

2,457,851.2112

Angular separation (arcsec)

0.08880

Eq. Temperature

1,505K

(1232 °C)

Insolation (S⊕)

849.50

Earth = 1.00

Earth Similarity (ESI)

0.107

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

Bakos et al. 2021

Instrument

Apogee 4K CCD Sensor

Publication

2021-07

Observation locale

Ground

Discovery cohort

Planets confirmed in 2021 at HATNet (6 shown).

HAT-P-59 b · Gas Giant HAT-P-63 b · Gas Giant HAT-P-62 b · Gas Giant HAT-P-58 b · Gas Giant HAT-P-60 b · Gas Giant HAT-P-64 b · Gas Giant

Host System: HAT-P-61

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,587 K — cooler than the Sun (5,778 K)

Estimated Age

2.60 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.938 R☉

Stellar Mass

1.004 M☉

Metallicity [Fe/H]

0.19

Extended Stellar Properties

Surface gravity (log g)

4.496 dex

Stellar density

1.715 g/cm³

Systemic radial velocity

4.81 km/s

Metallicity ratio

[Fe/H]

Distance

338.84 parsec

Light-years 1,105.15 ly

V-band magnitude

13.10 mag

Voyager-speed travel 19,489,266 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

2.923 mas

Total Proper Motion

24.107 mas/yr

PM Right Ascension

-11.02 mas/yr

PM Declination

-21.44 mas/yr

Galactic Cartesian (pc)

x = 0.161 · y = 0.621 · z = 0.768

Equatorial (J2000)

RA 75.48017° · Dec 50.13118°

Galactic ℓ, b

157.781° · 5.026°

Ecliptic λ, β

79.584° · 27.215°

HTM-20 index

-750365858