KELT-17 b
KELT-17 b is a hot Jupiter orbiting the A star KELT-17 in the constellation Cancer. It lies about 739 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is KELT-17 b?
KELT-17 b has a radius of 17.09 times that of Earth, or 1.53 times the radius of Jupiter. Its mass is 416 times that of Earth, giving it a density of 0.46 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is KELT-17 b in the Habitable Zone?
The position of KELT-17 b relative to the habitable zone of KELT-17 cannot be precisely determined from the available orbital data.
Temperature on KELT-17 b
The equilibrium temperature of KELT-17 b is about 2,087 K (1,814 °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 KELT-17 b — one full orbit around KELT-17 — lasts 3.08 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.049 AU — closer to its star than Mercury is to the Sun.
How Was KELT-17 b Discovered?
KELT-17 b was discovered in 2016 using the transit method, with observations from KELT.
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-17 b?
KELT-17 b is 738.7 light-years (226.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1288. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 13,001,120 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-17 b scores 0.05, ranking #5,241 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: KELT-17
KELT-17
- Spectral type
- A
- Surface temperature
- 7,454 K (Sun: 5,772 K)
- Mass
- 1.64 M☉
- Radius
- 1.65 R☉
- Luminosity
- 7.5100 L☉
- Age
- 0.7 billion years (Sun: 4.6)
Planetary System
KELT-17 b is the only planet known to orbit KELT-17 so far.
KELT-17 b — Complete Data
| Radius | 17.094 Earth radii (1.525 Jupiter radii) |
|---|---|
| Mass | 416.36 Earth masses (1.310 Jupiter masses) |
| Density | 0.46 g/cm³ (Earth: 5.51) |
| Orbital period | 3.08 days |
| Orbital distance | 0.049 AU |
| Equilibrium temperature | 2,087 K (1,814 °C) |
| Earth Similarity Index | 0.05 |
| Distance from Earth | 738.7 light-years (226.5 parsecs) |
| Constellation | Cancer |
| Discovery method | Transit |
| Discovery facility | KELT |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2019-12-02. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About KELT-17 b
Is KELT-17 b habitable?
KELT-17 b is not known to orbit within the habitable zone of KELT-17, and as a hot Jupiter it is an unlikely candidate for life as we know it.
How far away is KELT-17 b?
KELT-17 b is about 739 light-years from Earth in the constellation Cancer. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 13,001,120 years to get there.
How big is KELT-17 b compared to Earth?
KELT-17 b has 17.09 times the radius of Earth and about 416 times its mass.
How long is a year on KELT-17 b?
One orbit around KELT-17 takes 3.1 Earth days — short enough that 119 of its years would fit into one Earth year.
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