HD 207496 b
HD 207496 b is a super-Earth orbiting the K2.5 V star HD 207496 in the constellation Octans. It lies about 77 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is HD 207496 b?
HD 207496 b has a radius of 2.25 times that of Earth. Its mass is 6.1 times that of Earth, giving it a density of 3.17 g/cm³ — between that of rocky and gaseous planets.
Is HD 207496 b in the Habitable Zone?
HD 207496 b orbits inside the inner edge of the habitable zone of HD 207496. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 207496: 0.422–1.029 AU (conservative: 0.535–0.976 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HD 207496 b
The equilibrium temperature of HD 207496 b is about 743 K (470 °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 72.90 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HD 207496 b — one full orbit around HD 207496 — lasts 6.44 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.063 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.23).
How Was HD 207496 b Discovered?
HD 207496 b 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 207496 b?
HD 207496 b is 77.0 light-years (23.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1949. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,355,200 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 207496 b scores 0.26, ranking #2,901 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 207496
HD 207496
- Spectral type
- K2.5 V
- Surface temperature
- 4,819 K (Sun: 5,772 K)
- Mass
- 0.80 M☉
- Radius
- 0.77 R☉
- Age
- 0.5 billion years (Sun: 4.6)
Planetary System
HD 207496 b is the only planet known to orbit HD 207496 so far.
HD 207496 b — Complete Data
| Radius | 2.250 Earth radii (0.201 Jupiter radii) |
|---|---|
| Mass | 6.10 Earth masses (0.019 Jupiter masses) |
| Density | 3.17 g/cm³ (Earth: 5.51) |
| Orbital period | 6.44 days |
| Orbital distance | 0.063 AU |
| Eccentricity | 0.231 |
| Equilibrium temperature | 743 K (470 °C) |
| Stellar irradiation | 72.90× Earth |
| Earth Similarity Index | 0.26 |
| Distance from Earth | 77.0 light-years (23.6 parsecs) |
| Constellation | Octans |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-05-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 207496 b
Is HD 207496 b habitable?
No — HD 207496 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 207496 b?
HD 207496 b is about 77 light-years from Earth in the constellation Octans. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,355,200 years to get there.
How big is HD 207496 b compared to Earth?
HD 207496 b has 2.25 times the radius of Earth and about 6.1 times its mass.
How long is a year on HD 207496 b?
One orbit around HD 207496 takes 6.4 Earth days — short enough that 57 of its years would fit into one Earth year.
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