KELT-23 A b
KELT-23 A b is a hot Jupiter orbiting the G2 V star KELT-23 A in the constellation Ursa Minor. It lies about 412 light-years from Earth and was discovered in 2019 using the transit method.
How Big Is KELT-23 A b?
KELT-23 A b has a radius of 14.83 times that of Earth, or 1.32 times the radius of Jupiter. Its mass is 298 times that of Earth, giving it a density of 0.50 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is KELT-23 A b in the Habitable Zone?
KELT-23 A b orbits inside the inner edge of the habitable zone of KELT-23 A. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of KELT-23 A: 0.775–1.819 AU (conservative: 0.981–1.725 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 KELT-23 A b
The equilibrium temperature of KELT-23 A b is about 1,561 K (1,288 °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 991 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on KELT-23 A b — one full orbit around KELT-23 A — lasts 2.26 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.033 AU — closer to its star than Mercury is to the Sun.
How Was KELT-23 A b Discovered?
KELT-23 A b was discovered in 2019 using the transit method, with observations from KELT-North.
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 KELT-23 A b?
KELT-23 A b is 411.8 light-years (126.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1615. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 7,247,680 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. KELT-23 A b scores 0.06, ranking #5,117 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: KELT-23 A
KELT-23 A b belongs to a system of 2 stars; it orbits KELT-23 A.
KELT-23 A
- Spectral type
- G2 V
- Surface temperature
- 5,899 K (Sun: 5,772 K)
- Mass
- 0.94 M☉
- Radius
- 1.00 R☉
- Luminosity
- 1.0810 L☉
- Age
- 6.4 billion years (Sun: 4.6)
Planetary System
KELT-23 A b is the only planet known to orbit KELT-23 A so far.
KELT-23 A b — Complete Data
| Radius | 14.830 Earth radii (1.323 Jupiter radii) |
|---|---|
| Mass | 298.12 Earth masses (0.938 Jupiter masses) |
| Density | 0.50 g/cm³ (Earth: 5.51) |
| Orbital period | 2.26 days |
| Orbital distance | 0.033 AU |
| Equilibrium temperature | 1,561 K (1,288 °C) |
| Stellar irradiation | 991.18× Earth |
| Earth Similarity Index | 0.06 |
| Distance from Earth | 411.8 light-years (126.3 parsecs) |
| Constellation | Ursa Minor |
| Discovery method | Transit |
| Discovery facility | KELT-North |
| Discovery year | 2019 |
Data: NASA Exoplanet Archive, last updated 2019-06-07. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About KELT-23 A b
Is KELT-23 A b habitable?
No — KELT-23 A b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is KELT-23 A b?
KELT-23 A b is about 412 light-years from Earth in the constellation Ursa Minor. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 7,247,680 years to get there.
How big is KELT-23 A b compared to Earth?
KELT-23 A b has 14.83 times the radius of Earth and about 298 times its mass.
How long is a year on KELT-23 A b?
One orbit around KELT-23 A takes 2.3 Earth days — short enough that 162 of its years would fit into one Earth year.
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