Key parameters at a glance

A radius of 4.36 Earth radii
A mass of 25.00 Earth masses
Surface gravity around 1.32 g
An orbital period of 4.888 days
Semi-major axis 0.0526 AU
Equilibrium temperature 838 K (565 °C)
Distance from Earth 123.17 light-years
Earth Similarity Index 0.235
Travel time at Voyager 1 speed 2,172,135 years
Almost certainly tidally locked to its host star given the close orbit

1 sibling around HAT-P-11

HAT-P-11 b 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
HAT-P-11 b this	Neptune-like	4.36	25.00	4.888	838	2008
HAT-P-11 c	Gas Giant	13.20	851.78	3,361.000	—	2018

HAT-P-11 b Planet Profile

Physical Specs

Radius

4.36 R⊕

Radius (Jupiter)

0.389 R♃

Mass

25.00 M⊕

Mass (Jupiter)

0.079 M♃

Density

1.17 g/cm³

Surface Gravity

1.32 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.235

HZ Position Inner

Controversial No

Discovery

Year 2008

Method Transit

Facility HATNet

Telescope Canon 200mm f/1.8L

Size rank in cohort

Rank by radius

#479of 574

top 83.3%

This planet

4.36R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

HD 153557 c 4.36 R⊕ HD 106315 c 4.35 R⊕ Kepler-1668 b 4.35 R⊕

Metric	Earth	HAT-P-11 b	Jupiter
Radius (R⊕)	1.00	4.36	11.21
Mass (M⊕)	1.00	25.00	317.83
Density (g/cm³)	5.51	1.17	1.33
Surface Gravity (g)	1.00	1.32	2.53
Insolation (S⊕)	1.00	100.77	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	25.000 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	23.519 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HIP

HIP 97657

TIC

TIC 28230919

Gaia DR2

Gaia DR2 2086512227851023872

Gaia DR3

Gaia DR3 2086512227851023872

System

HAT-P-11

Percentile among Neptune-like cohort

Radius 4.360 R⊕ · percentile 16 / cohort 574

Mass 25.000 M⊕ · percentile 42 / cohort 574

Orbital period 4.89 d · percentile 20 / cohort 524

Distance 37.76 pc · percentile 11 / cohort 572

ESI 0.235 · percentile 37 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

4.888 days

Semi-major axis

0.0526 AU

Eccentricity

0.251

Inclination

89.03 °

Year Length

A year here lasts approximately 4.89 Earth days (1.3% of a terrestrial year) on a mildly elliptical path at a mean orbital distance of 0.0526 AU.

Transit Fingerprint

Depth

0.434 %

Duration

2.356 h

Impact parameter b

0.227

Rp / R★

0.057989

Transit midpoint (BJD)

2,454,957.8132

Photometric dip

Transit produces a flux drop of 4,342 ppm lasting ≈ 2.36 h.

Extended Orbital Architecture

Planet / star radius ratio

0.057989

Semi-major axis / stellar radius

16.718

Impact parameter (b)

0.227

RV semi-amplitude (K)

10.420 m/s

Occultation depth

0.001 ppm

Transit mid-time (BJD)

2,454,957.8132

Long. of periastron (ω)

28.00°

Sky-projected obliquity (λ)

133.90°

True obliquity (ψ)

104.90°

Angular separation (arcsec)

1.39000

Eq. Temperature

838K

(565 °C)

Insolation (S⊕)

100.77

Earth = 1.00

Earth Similarity (ESI)

0.235

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Astrometry

Positional wobble of the host star was measured.

Discovery Paper

Primary reference

Bakos et al. 2010

Instrument

2K CCD Sensor

Publication

2010-02

Observation locale

Ground

Discovery cohort

Planets confirmed in 2008 at HATNet (3 shown).

HAT-P-8 b · Gas Giant HAT-P-9 b · Gas Giant HAT-P-7 b · Gas Giant

Host System: HAT-P-11

Spectral Class

K-type orange

Effective Temperature

4,653 K — cooler than the Sun (5,778 K)

Estimated Age

2.69 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.683 R☉

Stellar Mass

0.811 M☉

Metallicity [Fe/H]

0.31

Extended Stellar Properties

Surface gravity (log g)

4.663 dex

Stellar density

3.700 g/cm³

Systemic radial velocity

-63.24 km/s

Rotational v·sin i

0.67 km/s

Rotation period

30.50 days

Activity index (log R'HK)

-4.350

Metallicity ratio

[Fe/H]

Distance

37.76 parsec

Light-years 123.17 ly

V-band magnitude

9.46 mag

Voyager-speed travel 2,172,135 yr

Multi-band Host Photometry — 14 bands

Astrometric Data

Parallax

26.451 mas

Total Proper Motion

264.869 mas/yr

PM Right Ascension

125.98 mas/yr

PM Declination

232.99 mas/yr

Galactic Cartesian (pc)

x = 0.311 · y = -0.591 · z = 0.744

Equatorial (J2000)

RA 297.71018° · Dec 48.08186°

Galactic ℓ, b

81.835° · 10.772°

Ecliptic λ, β

321.547° · 66.630°

HTM-20 index

2052377588

Observation Record

Photometric series

RV measurements

Transmission spectra

Archive notes

Similar Worlds

HD 153557 c

Neptune-like · K-type orange

Radius 4.36 R⊕ · 58.5 ly

Kepler-413 b

Neptune-like · K-type orange

Radius 4.35 R⊕ · 2,764.3 ly

HD 99492 c

Neptune-like · K-type orange

Radius 4.42 R⊕ · 59.4 ly

Kepler-411 c

Neptune-like · K-type orange

Radius 4.42 R⊕ · 501.2 ly

K2-55 b

Neptune-like · K-type orange

Radius 4.43 R⊕ · 520.3 ly

TOI-1803 c

Neptune-like · K-type orange

Radius 4.29 R⊕ · 388.9 ly

Explore Related Categories

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