HD 73583 c
HD 73583 c is a super-Earth orbiting the K4 V star HD 73583 in the constellation Hydra. It lies about 103 light-years from Earth and was discovered in 2022 using the transit method.
How Big Is HD 73583 c?
HD 73583 c has a radius of 2.39 times that of Earth. Its mass is 9.7 times that of Earth, giving it a density of 3.88 g/cm³ — between that of rocky and gaseous planets.
Is HD 73583 c in the Habitable Zone?
HD 73583 c orbits inside the inner edge of the habitable zone of HD 73583. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 73583: 0.317–0.782 AU (conservative: 0.401–0.741 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HD 73583 c
The equilibrium temperature of HD 73583 c is about 498 K (225 °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 10.20 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HD 73583 c — one full orbit around HD 73583 — lasts 18.9 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.124 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.08).
How Was HD 73583 c Discovered?
HD 73583 c 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 73583 c?
HD 73583 c is 103.0 light-years (31.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1923. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,812,800 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 73583 c scores 0.34, ranking #869 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 73583
HD 73583
- Spectral type
- K4 V
- Surface temperature
- 4,511 K (Sun: 5,772 K)
- Mass
- 0.73 M☉
- Radius
- 0.65 R☉
- Age
- 0.5 billion years (Sun: 4.6)
The HD 73583 Planetary System
HD 73583 c is one of 2 known planets in the HD 73583 system. Its siblings:
- HD 73583 b (Mini Neptune)
HD 73583 c — Complete Data
| Radius | 2.390 Earth radii (0.213 Jupiter radii) |
|---|---|
| Mass | 9.70 Earth masses (0.031 Jupiter masses) |
| Density | 3.88 g/cm³ (Earth: 5.51) |
| Orbital period | 18.88 days |
| Orbital distance | 0.124 AU |
| Eccentricity | 0.080 |
| Equilibrium temperature | 498 K (225 °C) |
| Stellar irradiation | 10.20× Earth |
| Earth Similarity Index | 0.34 |
| Distance from Earth | 103.0 light-years (31.6 parsecs) |
| Constellation | Hydra |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-03-16. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 73583 c
Is HD 73583 c habitable?
No — HD 73583 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 73583 c?
HD 73583 c is about 103 light-years from Earth in the constellation Hydra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,812,800 years to get there.
How big is HD 73583 c compared to Earth?
HD 73583 c has 2.39 times the radius of Earth and about 9.7 times its mass.
How long is a year on HD 73583 c?
One orbit around HD 73583 takes 18.9 Earth days — short enough that 19 of its years would fit into one Earth year.
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