Key parameters at a glance

A radius of 10.66 Earth radii
A mass of 2,866.81 Earth masses
Surface gravity around 25.23 g
An orbital period of 5.634 days
Semi-major axis 0.0681 AU
Equilibrium temperature 1,540 K (1267 °C)
Distance from Earth 416.74 light-years
Earth Similarity Index 0.102
Travel time at Voyager 1 speed 7,349,255 years

1 sibling around HAT-P-2

HAT-P-2 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-2 b this	Gas Giant	10.66	2,866.81	5.634	1,540	2007
HAT-P-2 c	Gas Giant	12.40	3,400.76	8,500.000	—	2023

HAT-P-2 b Planet Profile

Physical Specs

Radius

10.66 R⊕

Radius (Jupiter)

0.951 R♃

Mass

2,866.81 M⊕

Mass (Jupiter)

9.020 M♃

Density

7.29 g/cm³

Surface Gravity

25.23 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.102

HZ Position Inner

Controversial No

Discovery

Year 2007

Method Transit

Facility HATNet

Telescope Canon 200mm f/1.8L

Size rank in cohort

Rank by radius

#1711of 1771

top 96.6%

This planet

10.66R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

TOI-4214 b 10.68 R⊕ HATS-22 b 10.68 R⊕ Kepler-975 c 10.69 R⊕

Metric	Earth	HAT-P-2 b	Jupiter
Radius (R⊕)	1.00	10.66	11.21
Mass (M⊕)	1.00	2,866.81	317.83
Density (g/cm³)	5.51	7.29	1.33
Surface Gravity (g)	1.00	25.23	2.53
Insolation (S⊕)	1.00	588.52	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	2,866.812 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	2,739.695 M⊕	Lower bound from radial-velocity fitting.

Star Catalogue Identifiers

HD 147506

HIP

HIP 80076

TIC

TIC 39903405

Gaia DR2

Gaia DR2 1380825667768742144

Gaia DR3

Gaia DR3 1380825667768742144

System

HAT-P-2

Percentile among Gas Giant cohort

Radius 10.660 R⊕ · percentile 3 / cohort 1771

Mass 2,866.812 M⊕ · percentile 86 / cohort 1747

Orbital period 5.63 d · percentile 39 / cohort 1533

Distance 127.77 pc · percentile 40 / cohort 1759

ESI 0.102 · percentile 27 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

5.634 days

Semi-major axis

0.0681 AU

Eccentricity

0.517

Inclination

86.16 °

Year Length

A year here lasts approximately 5.63 Earth days (1.5% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0681 AU.

Transit Fingerprint

Depth

0.565 %

Duration

4.289 h

Impact parameter b

0.457

Rp / R★

0.067800

Transit midpoint (BJD)

2,458,657.6629

Photometric dip

Transit produces a flux drop of 5,651 ppm lasting ≈ 4.29 h.

Extended Orbital Architecture

Planet / star radius ratio

0.067800

Semi-major axis / stellar radius

10.280

Impact parameter (b)

0.457

RV semi-amplitude (K)

953.300 m/s

Occultation depth

0.097 ppm

Transit mid-time (BJD)

2,458,657.6629

Long. of periastron (ω)

188.01°

Sky-projected obliquity (λ)

0.20°

Angular separation (arcsec)

0.53300

Eq. Temperature

1,540K

(1267 °C)

Insolation (S⊕)

588.52

Earth = 1.00

Earth Similarity (ESI)

0.102

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. 2007

Instrument

2K CCD Sensor

Publication

2007-11

Observation locale

Ground

Discovery cohort

Planets confirmed in 2007 at HATNet (4 shown).

HAT-P-3 b · Gas Giant HAT-P-5 b · Gas Giant HAT-P-6 b · Gas Giant HAT-P-4 b · Gas Giant

Host System: HAT-P-2

Spectral Class

F-type yellow-white

Effective Temperature

6,380 K — hotter than the Sun (5,778 K)

Estimated Age

1.44 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.390 R☉

Stellar Mass

1.330 M☉

Metallicity [Fe/H]

0.18

Extended Stellar Properties

Surface gravity (log g)

4.160 dex

Stellar density

0.434 g/cm³

Systemic radial velocity

-0.22 km/s

Rotational v·sin i

20.80 km/s

Metallicity ratio

[Fe/H]

Distance

127.77 parsec

Light-years 416.74 ly

V-band magnitude

8.72 mag

Voyager-speed travel 7,349,255 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

7.797 mas

Total Proper Motion

30.965 mas/yr

PM Right Ascension

-10.31 mas/yr

PM Declination

-29.20 mas/yr

Galactic Cartesian (pc)

x = -0.317 · y = -0.684 · z = 0.657

Equatorial (J2000)

RA 245.15143° · Dec 41.04796°

Galactic ℓ, b

65.021° · 45.232°

Ecliptic λ, β

229.158° · 61.012°

HTM-20 index

-1362549155

Observation Record

Photometric series

RV measurements

Stellar spectra

Transmission spectra

Emission spectra

Archive notes