TOI-1408 b
TOI-1408 b is a hot Jupiter orbiting the F8 V star TOI-1408 in the constellation Cepheus. It lies about 455 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-1408 b?
TOI-1408 b has a radius of 25.00 times that of Earth, or 2.23 times the radius of Jupiter. Its mass is 593 times that of Earth, giving it a density of 0.18 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-1408 b in the Habitable Zone?
TOI-1408 b orbits inside the inner edge of the habitable zone of TOI-1408. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-1408: 1.265–2.956 AU (conservative: 1.602–2.803 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Orbit and Year Length
A year on TOI-1408 b — one full orbit around TOI-1408 — lasts 4.43 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.058 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.002).
How Was TOI-1408 b Discovered?
TOI-1408 b was discovered in 2023 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is TOI-1408 b?
TOI-1408 b is 454.9 light-years (139.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1572. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 8,006,240 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. TOI-1408 b scores 0.06, ranking #5,227 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-1408
TOI-1408
- Spectral type
- F8 V
- Surface temperature
- 6,117 K (Sun: 5,772 K)
- Mass
- 1.31 M☉
- Radius
- 1.53 R☉
- Luminosity
- 2.9600 L☉
- Age
- 2.7 billion years (Sun: 4.6)
The TOI-1408 Planetary System
TOI-1408 b is one of 2 known planets in the TOI-1408 system. Its siblings:
- TOI-1408 c (Super Earth)
TOI-1408 b — Complete Data
| Radius | 25.000 Earth radii (2.230 Jupiter radii) |
|---|---|
| Mass | 593.00 Earth masses (1.866 Jupiter masses) |
| Density | 0.18 g/cm³ (Earth: 5.51) |
| Orbital period | 4.43 days |
| Orbital distance | 0.058 AU |
| Eccentricity | 0.002 |
| Earth Similarity Index | 0.06 |
| Distance from Earth | 454.9 light-years (139.5 parsecs) |
| Constellation | Cepheus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2024-08-07. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-1408 b
Is TOI-1408 b habitable?
No — TOI-1408 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-1408 b?
TOI-1408 b is about 455 light-years from Earth in the constellation Cepheus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 8,006,240 years to get there.
How big is TOI-1408 b compared to Earth?
TOI-1408 b has 25.00 times the radius of Earth and about 593 times its mass.
How long is a year on TOI-1408 b?
One orbit around TOI-1408 takes 4.4 Earth days — short enough that 83 of its years would fit into one Earth year.
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