HIP 29442 d
HIP 29442 d is a super-Earth orbiting TOI-469 in the constellation Lepus. It lies about 222 light-years from Earth and was discovered in 2023 using the radial velocity method.
How Big Is HIP 29442 d?
HIP 29442 d has a radius of 1.54 times that of Earth. Its mass is 5.1 times that of Earth.
Is HIP 29442 d in the Habitable Zone?
HIP 29442 d orbits inside the inner edge of the habitable zone of TOI-469. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-469: 0.634–1.516 AU (conservative: 0.803–1.437 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HIP 29442 d
The equilibrium temperature of HIP 29442 d is about 920 K (647 °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 203 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HIP 29442 d — one full orbit around TOI-469 — lasts 6.43 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.067 AU — closer to its star than Mercury is to the Sun.
How Was HIP 29442 d Discovered?
HIP 29442 d was discovered in 2023 using the radial velocity method, with observations from Paranal Observatory.
The radial velocity method measures the subtle wobble of a star caused by the gravitational pull of an orbiting planet, visible as periodic shifts in the star's light spectrum. The size of the wobble reveals the planet's minimum mass.
How Far Away Is HIP 29442 d?
HIP 29442 d is 222.4 light-years (68.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1804. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,914,240 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. HIP 29442 d scores 0.29, ranking #1,693 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-469
TOI-469
- Surface temperature
- 5,289 K (Sun: 5,772 K)
- Mass
- 0.90 M☉
- Radius
- 0.98 R☉
- Age
- 11.2 billion years (Sun: 4.6)
The TOI-469 Planetary System
HIP 29442 d is one of 3 known planets in the TOI-469 system. Its siblings:
- HIP 29442 c (Super Earth)
- TOI-469.01 (Puffy Planet)
HIP 29442 d — Complete Data
| Radius | 1.538 Earth radii (0.137 Jupiter radii) |
|---|---|
| Mass | 5.14 Earth masses (0.016 Jupiter masses) |
| Orbital period | 6.43 days |
| Orbital distance | 0.067 AU |
| Equilibrium temperature | 920 K (647 °C) |
| Stellar irradiation | 203.00× Earth |
| Earth Similarity Index | 0.29 |
| Distance from Earth | 222.4 light-years (68.2 parsecs) |
| Constellation | Lepus |
| Discovery method | Radial Velocity |
| Discovery facility | Paranal Observatory |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2024-09-13. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HIP 29442 d
Is HIP 29442 d habitable?
No — HIP 29442 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HIP 29442 d?
HIP 29442 d is about 222 light-years from Earth in the constellation Lepus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,914,240 years to get there.
How big is HIP 29442 d compared to Earth?
HIP 29442 d has 1.54 times the radius of Earth and about 5.1 times its mass.
How long is a year on HIP 29442 d?
One orbit around TOI-469 takes 6.4 Earth days — short enough that 57 of its years would fit into one Earth year.
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