HD 2685 b
HD 2685 b is a hot Jupiter orbiting HD 2685 in the constellation Hydrus. It lies about 642 light-years from Earth and was discovered in 2019 using the transit method.
How Big Is HD 2685 b?
HD 2685 b has a radius of 16.14 times that of Earth, or 1.44 times the radius of Jupiter. Its mass is 372 times that of Earth.
Is HD 2685 b in the Habitable Zone?
HD 2685 b orbits inside the inner edge of the habitable zone of HD 2685. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 2685: 1.525–3.527 AU (conservative: 1.932–3.344 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HD 2685 b
The equilibrium temperature of HD 2685 b is about 2,061 K (1,788 °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.
Orbit and Year Length
A year on HD 2685 b — one full orbit around HD 2685 — lasts 4.13 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.057 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.09).
How Was HD 2685 b Discovered?
HD 2685 b was discovered in 2019 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 2685 b?
HD 2685 b is 642.0 light-years (196.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1384. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 11,299,200 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 2685 b scores 0.06, ranking #5,200 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 2685
HD 2685
- Surface temperature
- 6,801 K (Sun: 5,772 K)
- Mass
- 1.43 M☉
- Radius
- 1.56 R☉
- Luminosity
- 4.6600 L☉
- Age
- 1.3 billion years (Sun: 4.6)
Planetary System
HD 2685 b is the only planet known to orbit HD 2685 so far.
HD 2685 b — Complete Data
| Radius | 16.141 Earth radii (1.440 Jupiter radii) |
|---|---|
| Mass | 371.86 Earth masses (1.170 Jupiter masses) |
| Orbital period | 4.13 days |
| Orbital distance | 0.057 AU |
| Eccentricity | 0.091 |
| Equilibrium temperature | 2,061 K (1,788 °C) |
| Earth Similarity Index | 0.06 |
| Distance from Earth | 642.0 light-years (196.9 parsecs) |
| Constellation | Hydrus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2019 |
Data: NASA Exoplanet Archive, last updated 2019-10-18. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 2685 b
Is HD 2685 b habitable?
No — HD 2685 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 2685 b?
HD 2685 b is about 642 light-years from Earth in the constellation Hydrus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 11,299,200 years to get there.
How big is HD 2685 b compared to Earth?
HD 2685 b has 16.14 times the radius of Earth and about 372 times its mass.
How long is a year on HD 2685 b?
One orbit around HD 2685 takes 4.1 Earth days — short enough that 89 of its years would fit into one Earth year.
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