Key parameters at a glance

A radius of 7.66 Earth radii
A mass of 11.30 Earth masses
Surface gravity around 0.19 g
An orbital period of 95.400 days
Semi-major axis 0.4607 AU
Equilibrium temperature 255 K (-19 °C)
Distance from Earth 1,301.42 light-years
Earth Similarity Index 0.464
Travel time at Voyager 1 speed 22,950,503 years

Context from the literature

TOI-1338 b, also known as BEBOP-1b, is a gas giant circumbinary planet orbiting around the binary star system of TOI-1338. First identified by then-17-year-old Wolf Cukier, it was the first circumbinary planet discovered using the Transiting Exoplanet Survey Satellite (TESS). The planet was discovered in the summer of 2019, and its discovery was announced 6 January 2020.

Excerpted from Wikipedia · full article

1 sibling around TOI-1338 A

TOI-1338 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
TOI-1338 b this	Neptune-like	7.66	11.30	95.400	255	2020
TOI-1338 c	Gas Giant	10.30	75.40	215.790	—	2023

brightness_6

Circumbinary planet

TOI-1338 b orbits a binary-star pair rather than a single host — a minority architecture in the confirmed catalogue.

TOI-1338 b Planet Profile

Physical Specs

Radius

7.66 R⊕

Radius (Jupiter)

0.684 R♃

Mass

11.30 M⊕

Mass (Jupiter)

0.036 M♃

Density

0.56 g/cm³

Surface Gravity

0.19 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.464

HZ Position Habitable

Controversial No

Discovery

Year 2020

Method Transit

Facility Transiting Exoplanet Survey Satellite (TESS)

Telescope 0.1 m TESS Telescope

Size rank in cohort

Rank by radius

#169of 574

top 29.3%

This planet

7.66R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

K2-60 b 7.66 R⊕ Kepler-952 b 7.65 R⊕ Kepler-118 c 7.68 R⊕

Metric	Earth	TOI-1338 b	Jupiter
Radius (R⊕)	1.00	7.66	11.21
Mass (M⊕)	1.00	11.30	317.83
Density (g/cm³)	5.51	0.56	1.33
Surface Gravity (g)	1.00	0.19	2.53
Insolation (S⊕)	1.00	0.99	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	11.300 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 260128333

Gaia DR2

Gaia DR2 5494443978353833088

Gaia DR3

Gaia DR3 5494443978353833088

System

TOI-1338

Percentile among Neptune-like cohort

Radius 7.661 R⊕ · percentile 71 / cohort 574

Mass 11.300 M⊕ · percentile 4 / cohort 574

Orbital period 95.40 d · percentile 81 / cohort 524

Distance 399.02 pc · percentile 53 / cohort 572

ESI 0.464 · percentile 84 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

95.400 days

Semi-major axis

0.4607 AU

Eccentricity

0.033

Inclination

90.49 °

Year Length

A year here lasts approximately 95.40 Earth days (26.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.4607 AU.

Transit Fingerprint

Depth

0.260 %

Duration

11.632 h

Rp / R★

0.047240

Transit midpoint (BJD)

2,459,238.2195

Photometric dip

Transit produces a flux drop of 2,600 ppm lasting ≈ 11.63 h.

Extended Orbital Architecture

Planet / star radius ratio

0.047240

RV semi-amplitude (K)

2.400 m/s

Transit mid-time (BJD)

2,459,238.2195

Long. of periastron (ω)

71.90°

Angular separation (arcsec)

1.15000

Eq. Temperature

255K

(-19 °C)

Insolation (S⊕)

0.99

Earth = 1.00

Earth Similarity (ESI)

0.464

0 = alien, 1 = Earth-identical

Within the conservative habitable zone — surface water would be frozen.

Detection Signatures

Transit photometry

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

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Kostov et al. 2020

Instrument

TESS CCD Array

Publication

2020-06

Observation locale

Space

Discovery cohort

Planets confirmed in 2020 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).

TOI-700 d · Rocky Terrestrial TOI-237 b · Super-Earth TOI-700 b · Rocky Terrestrial TOI-1266 c · Super-Earth LTT 3780 c · Sub-Neptune TOI-700 c · Sub-Neptune TOI-776 c · Sub-Neptune TOI-942 c · Neptune-like TOI-776 b · Super-Earth TOI-1266 b · Sub-Neptune TOI-540 b · Rocky Terrestrial LHS 1815 b · Rocky Terrestrial

Host System: TOI-1338 A

Spectral Class

F-type yellow-white

Effective Temperature

5,723 K — cooler than the Sun (5,778 K)

Estimated Age

4.40 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.313 R☉

Stellar Mass

1.094 M☉

Metallicity [Fe/H]

0.01

Extended Stellar Properties

Surface gravity (log g)

4.000 dex

Stellar density

0.411 g/cm³

Systemic radial velocity

30.75 km/s

Rotational v·sin i

3.60 km/s

Rotation period

19.00 days

Metallicity ratio

[Fe/H]

Distance

399.02 parsec

Light-years 1,301.42 ly

V-band magnitude

11.72 mag

Voyager-speed travel 22,950,503 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

2.477 mas

Total Proper Motion

36.523 mas/yr

PM Right Ascension

-12.26 mas/yr

PM Declination

34.40 mas/yr

Galactic Cartesian (pc)

x = -0.019 · y = 0.507 · z = -0.862

Equatorial (J2000)

RA 92.13310° · Dec -59.54099°

Galactic ℓ, b

268.412° · -28.491°

Ecliptic λ, β

98.796° · -82.915°

HTM-20 index

-296798817

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