TOI-451 d
TOI-451 d is a puffy low-density planet orbiting the G8 V star TOI-451 in the constellation Eridanus. It lies about 404 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is TOI-451 d?
TOI-451 d has a radius of 3.93 times that of Earth. Its mass is 10.2 times that of Earth, giving it a density of 0.92 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-451 d in the Habitable Zone?
TOI-451 d orbits inside the inner edge of the habitable zone of TOI-451. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-451: 0.586–1.393 AU (conservative: 0.743–1.321 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-451 d
The equilibrium temperature of TOI-451 d is about 714 K (441 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 43.20 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-451 d — one full orbit around TOI-451 — lasts 16.4 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.117 AU — closer to its star than Mercury is to the Sun.
How Was TOI-451 d Discovered?
TOI-451 d was discovered in 2020 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-451 d?
TOI-451 d is 403.6 light-years (123.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1623. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 7,103,360 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-451 d scores 0.20, ranking #3,880 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-451
TOI-451 d belongs to a system of 2 stars; it orbits TOI-451.
TOI-451
- Spectral type
- G8 V
- Surface temperature
- 5,490 K (Sun: 5,772 K)
- Mass
- 0.93 M☉
- Radius
- 0.85 R☉
- Luminosity
- 0.5900 L☉
- Age
- 0.1 billion years (Sun: 4.6)
The TOI-451 Planetary System
TOI-451 d is one of 3 known planets in the TOI-451 system. Its siblings:
TOI-451 d — Complete Data
| Radius | 3.930 Earth radii (0.351 Jupiter radii) |
|---|---|
| Mass | 10.20 Earth masses (0.032 Jupiter masses) |
| Density | 0.92 g/cm³ (Earth: 5.51) |
| Orbital period | 16.36 days |
| Orbital distance | 0.117 AU |
| Equilibrium temperature | 714 K (441 °C) |
| Stellar irradiation | 43.20× Earth |
| Earth Similarity Index | 0.20 |
| Distance from Earth | 403.6 light-years (123.7 parsecs) |
| Constellation | Eridanus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2026-03-19. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-451 d
Is TOI-451 d habitable?
No — TOI-451 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-451 d?
TOI-451 d is about 404 light-years from Earth in the constellation Eridanus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 7,103,360 years to get there.
How big is TOI-451 d compared to Earth?
TOI-451 d has 3.93 times the radius of Earth and about 10.2 times its mass.
How long is a year on TOI-451 d?
One orbit around TOI-451 takes 16.4 Earth days — short enough that 22 of its years would fit into one Earth year.
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