K2-236b
First exoplanet discovered by Indian scientists, a close-in Neptune-like world.
K2-236b is a Neptune-like exoplanet orbiting an F-type star, also designated EPIC 211945201 b. It was discovered in 2018 using the transit method and is notable as the first exoplanet discovered by scientists based in India.
Quick Facts
- Discovered
- May 10, 2017
- Discovery Method
- Doppler spectroscopy (Transit)
- Semimajor
- 0.148 AU
- Inclination
- 87.9°
- Single Temperature
- 817 K
- Semi-Amplitude
- 5.7 m/s
Facts from the source article.
Lore & Background
K2-236b was identified as a planetary candidate from K2 photometry in Campaigns 5 and 16. The exoplanet transits a bright star (Vmag = 10.15, G0 spectral type) in a 19.492-day orbit. The photometric data combined with false positive probability calculations using VESPA may not be sufficient to confirm the planetary scenario, but high-resolution spectroscopic observations were taken using the PARAS spectrograph (19 radial velocity observations) over a time baseline of 420 days.
The data show that the planet has a radius of 6.12 ± 0.1 and a mass of 27 Earths. Its density is given as a value in g/cm³. Based on mass and radius, it is estimated that the heavy element content is 60–70% of the total mass. The surface temperature of the planet was found to be around 817 K, as it is very close to the host star. It is seven times nearer to its star compared to the Earth–Sun distance, placing the exoplanet in the uninhabitable zone.
Reader's Guide
K2-236b is significant as the first exoplanet discovered by scientists based in India, marking a milestone for Indian astronomy. Its discovery is of importance for understanding the formation mechanism of super-Neptune or sub-Saturn planets that are too close to the host star. The planet orbits its star in about 19 terrestrial days at a distance of 0.148 AU, closer than the internal limit of the habitable zone. With a low density, it may be composed of gas. The host star, EPIC 211945201, is an F-type star aged 4 billion years, located in the constellation of Cancer at a distance of 596 light-years from the Sun. The planet's high surface temperature of 817 K and its proximity to the star confirm it is uninhabitable. The heavy element content of 60–70% of the total mass provides clues to its internal composition and formation history.
Did You Know?
- K2-236b is also called EPIC 211945201 b.
- Its mass is 27 Earths and it orbits its star every 19.5 days.
Frequently Asked Questions
What is K2-236b?
K2-236b is a Neptune-class exoplanet that circles a hot F-type star, and it also goes by the catalog name EPIC 211945201 b. It was identified in 2018 through the transit method, making it one of the more recently added entries in the exoplanet registry.
Why is K2-236b considered a milestone discovery?
It holds the distinction of being the first exoplanet identified by a team of researchers based in India. That achievement marked a significant moment for Indian astronomy and broadened the international footprint of exoplanet science.
How does K2-236b compare in size and orbit to Earth?
At roughly 27 Earth masses, it sits firmly in the Neptune-like category rather than the super-Earth range. It completes one orbit around its host star every 19.5 days at a semi-major axis of about 0.148 AU, placing it well inside the habitable zone.
What kind of star does K2-236b orbit?
Its host is an F-type star, which means it is slightly hotter and more luminous than the Sun. That stellar classification gives the planet a brighter, bluer environment than an Earth-like system would experience.
How did astronomers detect K2-236b?
The planet was found using the transit method, where its passage in front of the star causes a small, periodic dip in brightness. The K2 mission data from 2018 provided the photometric signal that revealed this close-in world.
More in Transiting Exoplanets, Part 4 1-24
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