HD 238090 b
HD 238090 b is a super-Earth orbiting the M0.0 V star HD 238090 in the constellation Ursa Major. It lies about 50 light-years from Earth and was discovered in 2020 using the radial velocity method.
Is HD 238090 b in the Habitable Zone?
HD 238090 b orbits inside the inner edge of the habitable zone of HD 238090. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 238090: 0.215–0.547 AU (conservative: 0.273–0.518 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HD 238090 b
The equilibrium temperature of HD 238090 b is about 470 K (196 °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 8.10 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HD 238090 b — one full orbit around HD 238090 — lasts 13.7 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.093 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.30), swinging dramatically closer to and farther from its star.
How Was HD 238090 b Discovered?
HD 238090 b was discovered in 2020 using the radial velocity method, with observations from Multiple Observatories.
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 HD 238090 b?
HD 238090 b is 49.7 light-years (15.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1977. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 874,720 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 238090 b scores 0.36, ranking #672 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 238090
HD 238090
- Spectral type
- M0.0 V
- Surface temperature
- 3,933 K (Sun: 5,772 K)
- Mass
- 0.58 M☉
- Radius
- 0.57 R☉
- Luminosity
- 0.0702 L☉
Planetary System
HD 238090 b is the only planet known to orbit HD 238090 so far.
HD 238090 b — Complete Data
| Mass (best estimate) | 6.89 Earth masses |
|---|---|
| Orbital period | 13.67 days |
| Orbital distance | 0.093 AU |
| Eccentricity | 0.300 |
| Equilibrium temperature | 470 K (196 °C) |
| Stellar irradiation | 8.10× Earth |
| Earth Similarity Index | 0.36 |
| Distance from Earth | 49.7 light-years (15.2 parsecs) |
| Constellation | Ursa Major |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2021-02-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 238090 b
Is HD 238090 b habitable?
No — HD 238090 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 238090 b?
HD 238090 b is about 50 light-years from Earth in the constellation Ursa Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 874,720 years to get there.
How long is a year on HD 238090 b?
One orbit around HD 238090 takes 13.7 Earth days — short enough that 27 of its years would fit into one Earth year.
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