Key parameters at a glance

A radius of 14.01 Earth radii
A mass of 451.32 Earth masses
Surface gravity around 2.30 g
An orbital period of 4.125 days
Semi-major axis 0.0552 AU
Equilibrium temperature 1,630 K (1357 °C)
Distance from Earth 889.28 light-years
Earth Similarity Index 0.079
Travel time at Voyager 1 speed 15,682,463 years

XO-4 b Planet Profile

Physical Specs

Radius

14.01 R⊕

Radius (Jupiter)

1.250 R♃

Mass

451.32 M⊕

Mass (Jupiter)

1.420 M♃

Density

0.83 g/cm³

Surface Gravity

2.30 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.079

HZ Position Inner

Controversial No

Discovery

Year 2010

Method Transit

Facility Lowell Observatory

Telescope Perkins 1.8 m Telescope

Size rank in cohort

Rank by radius

#408of 1771

top 23.0%

This planet

14.01R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

WASP-185 b 14.01 R⊕ Ross 458 c 14.01 R⊕ TOI-4465 b 14.01 R⊕

Metric	Earth	XO-4 b	Jupiter
Radius (R⊕)	1.00	14.01	11.21
Mass (M⊕)	1.00	451.32	317.83
Density (g/cm³)	5.51	0.83	1.33
Surface Gravity (g)	1.00	2.30	2.53
Insolation (S⊕)	1.00	1,112.27	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	451.319 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 51234631

Gaia DR2

Gaia DR2 990291507088739072

Gaia DR3

Gaia DR3 990291507088739072

System

XO-4

Percentile among Gas Giant cohort

Radius 14.011 R⊕ · percentile 77 / cohort 1771

Mass 451.319 M⊕ · percentile 46 / cohort 1747

Orbital period 4.13 d · percentile 30 / cohort 1533

Distance 272.66 pc · percentile 57 / cohort 1759

ESI 0.079 · percentile 18 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

4.125 days

Semi-major axis

0.0552 AU

Eccentricity

0.000

Inclination

88.80 °

Year Length

A year here lasts approximately 4.13 Earth days (1.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0552 AU.

Transit Fingerprint

Depth

0.780 %

Duration

4.454 h

Rp / R★

0.088100

Transit midpoint (BJD)

2,456,878.4730

Photometric dip

Transit produces a flux drop of 7,800 ppm lasting ≈ 4.45 h.

Extended Orbital Architecture

Planet / star radius ratio

0.088100

Semi-major axis / stellar radius

7.680

RV semi-amplitude (K)

168.600 m/s

Transit mid-time (BJD)

2,456,878.4730

Long. of periastron (ω)

240.00°

Sky-projected obliquity (λ)

-46.70°

Angular separation (arcsec)

0.20300

Eq. Temperature

1,630K

(1357 °C)

Insolation (S⊕)

1,112.27

Earth = 1.00

Earth Similarity (ESI)

0.079

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

Southworth 2010

Instrument

PRISM CCD

Publication

2010-11

Observation locale

Ground

Host System: XO-4

Spectral Class

F-type yellow-white

Effective Temperature

6,397 K — hotter than the Sun (5,778 K)

Estimated Age

2.10 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.450 R☉

Stellar Mass

1.100 M☉

Metallicity [Fe/H]

-0.04

Extended Stellar Properties

Surface gravity (log g)

4.180 dex

Stellar density

0.500 g/cm³

Systemic radial velocity

1.64 km/s

Rotational v·sin i

8.80 km/s

Metallicity ratio

[Fe/H]

Distance

272.66 parsec

Light-years 889.28 ly

V-band magnitude

10.81 mag

Voyager-speed travel 15,682,463 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

3.639 mas

Total Proper Motion

17.800 mas/yr

PM Right Ascension

-16.99 mas/yr

PM Declination

5.31 mas/yr

Galactic Cartesian (pc)

x = -0.183 · y = 0.493 · z = 0.851

Equatorial (J2000)

RA 110.38803° · Dec 58.26811°

Galactic ℓ, b

158.635° · 26.689°

Ecliptic λ, β

103.044° · 35.749°

HTM-20 index

1478754909

Observation Record

Photometric series

RV measurements

Emission spectra