HD 260655 b
HD 260655 b is a terrestrial planet orbiting the M0 V star HD 260655 in the constellation Gemini. It lies about 33 light-years from Earth and was discovered in 2022 using the transit method.
How Big Is HD 260655 b?
HD 260655 b has a radius of 1.24 times that of Earth. Its mass is 2.1 times that of Earth, giving it a density of 6.20 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is HD 260655 b in the Habitable Zone?
HD 260655 b orbits inside the inner edge of the habitable zone of HD 260655. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 260655: 0.155–0.397 AU (conservative: 0.197–0.376 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on HD 260655 b
The equilibrium temperature of HD 260655 b is about 709 K (436 °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 42.20 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HD 260655 b — one full orbit around HD 260655 — lasts 2.77 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.029 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.039).
How Was HD 260655 b Discovered?
HD 260655 b was discovered in 2022 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 260655 b?
HD 260655 b is 32.6 light-years (10.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1994. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 573,760 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 260655 b scores 0.32, ranking #1,007 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 260655
HD 260655
- Spectral type
- M0 V
- Surface temperature
- 3,803 K (Sun: 5,772 K)
- Mass
- 0.44 M☉
- Radius
- 0.44 R☉
- Luminosity
- 0.0363 L☉
- Age
- 5.0 billion years (Sun: 4.6)
The HD 260655 Planetary System
HD 260655 b is one of 2 known planets in the HD 260655 system. Its siblings:
- HD 260655 c (Super Earth)
HD 260655 b — Complete Data
| Radius | 1.240 Earth radii (0.111 Jupiter radii) |
|---|---|
| Mass | 2.14 Earth masses (0.007 Jupiter masses) |
| Density | 6.20 g/cm³ (Earth: 5.51) |
| Orbital period | 2.77 days |
| Orbital distance | 0.029 AU |
| Eccentricity | 0.039 |
| Equilibrium temperature | 709 K (436 °C) |
| Stellar irradiation | 42.20× Earth |
| Earth Similarity Index | 0.32 |
| Distance from Earth | 32.6 light-years (10.0 parsecs) |
| Constellation | Gemini |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-06-27. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 260655 b
Is HD 260655 b habitable?
No — HD 260655 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 260655 b?
HD 260655 b is about 33 light-years from Earth in the constellation Gemini. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 573,760 years to get there.
How big is HD 260655 b compared to Earth?
HD 260655 b has 1.24 times the radius of Earth and about 2.1 times its mass.
How long is a year on HD 260655 b?
One orbit around HD 260655 takes 2.8 Earth days — short enough that 132 of its years would fit into one Earth year.
Explore HD 260655 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
