HD 22946 d
HD 22946 d is a super-Earth orbiting HD 22946 in the constellation Eridanus. It lies about 205 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is HD 22946 d?
HD 22946 d has a radius of 2.61 times that of Earth. Its mass is 26.6 times that of Earth, giving it a density of 10.80 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is HD 22946 d in the Habitable Zone?
HD 22946 d orbits inside the inner edge of the habitable zone of HD 22946. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 22946: 0.933–2.178 AU (conservative: 1.182–2.065 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HD 22946 d
The equilibrium temperature of HD 22946 d is about 546 K (273 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 18.56 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HD 22946 d — one full orbit around HD 22946 — lasts 47.4 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.296 AU — closer to its star than Mercury is to the Sun.
How Was HD 22946 d Discovered?
HD 22946 d 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 HD 22946 d?
HD 22946 d is 204.8 light-years (62.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1822. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,604,480 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. HD 22946 d scores 0.29, ranking #1,761 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 22946
HD 22946
- Surface temperature
- 6,169 K (Sun: 5,772 K)
- Mass
- 1.10 M☉
- Radius
- 1.12 R☉
- Age
- 2.5 billion years (Sun: 4.6)
The HD 22946 Planetary System
HD 22946 d is one of 3 known planets in the HD 22946 system. Its siblings:
HD 22946 d — Complete Data
| Radius | 2.607 Earth radii (0.233 Jupiter radii) |
|---|---|
| Mass | 26.57 Earth masses (0.084 Jupiter masses) |
| Density | 10.80 g/cm³ (Earth: 5.51) |
| Orbital period | 47.42 days |
| Orbital distance | 0.296 AU |
| Equilibrium temperature | 546 K (273 °C) |
| Stellar irradiation | 18.56× Earth |
| Earth Similarity Index | 0.29 |
| Distance from Earth | 204.8 light-years (62.8 parsecs) |
| Constellation | Eridanus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-07-10. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 22946 d
Is HD 22946 d habitable?
No — HD 22946 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 22946 d?
HD 22946 d is about 205 light-years from Earth in the constellation Eridanus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,604,480 years to get there.
How big is HD 22946 d compared to Earth?
HD 22946 d has 2.61 times the radius of Earth and about 26.6 times its mass.
How long is a year on HD 22946 d?
One orbit around HD 22946 takes 47.4 Earth days.
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