K2-236b

Short description: Exoplanet

K2-236b

A high angular resolution image EPIC 211945201 taken using the NIRC2 instrument on the 10m Keck II telescope

Discovery[1]
Discovery date| May 10, 2017

Detection method

| Doppler spectroscopy (Transit)
Designations

Alternative names

| EPIC 211945201 b
Orbital characteristics

Semi-major axis

| 0.148 AU
Orbital period| 19.4921498(77) d[2]
Inclination| 87.9°
Semi-amplitude| 5.7 m/s
Physical characteristics
Mean radius| 0.546 RJ
Mass| 0.085 Jupiter mass
Physics| 886.35 K

K2-236b is a Neptune-like exoplanet that orbits an F-type star. It is also called EPIC 211945201 b. Its mass is 27 Earths, it takes 19.5 days to complete one orbit of its star, and is 0.148 AU from its star. Its discovery was announced in 2018.[3] This was the first exoplanet discovered by scientists based in India . The discoverers were Abhijit Chakraborty (PRL), Arpita Roy (Caltech), Rishikesh Sharma (PRL), Suvrath Mahadevan (Penn State), Priyanka Chaturvedi (Thüringer Landessternwarte Tautenburg), Neelam J.S.S.V Prasad (PRL), and B. G. Anandarao (PRL).[1]

## Contents

* 1 Overview
* 2 Discovery
* 3 See also
* 4 References

## Overview

The exoplanet K2-236b was discovered in 2018 using the transit method. Using this method, astronomers can see everything from methane to water vapor on other planets by photometry.[4] It is the only planet orbiting around EPIC 211945201, a G0 class star, situated in the constellation of Cancer in 596 light-years from the Sun. Its host star is aged 4 billion years. K2-236b orbits its star in about 19 terrestrial days.[5] It orbits closer to the star than the internal limit of the habitable zone. It has a low density and may be composed of gas.

## Discovery

K2-236b was found to be a planetary candidate from K2 photometry in Campaigns 5 & 16\. The exoplanet transits the 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 are taken using the PARAS spectrograph (19 radial velocity observations) over a time-baseline of 420 days.[1]

The data shows that the planet has a radius of 6.12 ± 0.1 R⊕, and a mass of 27+14
−12.6 M⊕. It consists of a density of 0.65+0.34
−0.30 g/cm3. Based on the mass and radius, it estimates that the heavy element content is 60-70 % of the total mass.[1] The surface temperature of the planet was found to be around 776.35 K, as it is very close to the host star.[6] It is seven times nearer to its star, in comparison with Earth-Sun distance. This shows that the extra-solar planet is in the uninhabitable zone. The discovery is of importance for understanding the formation mechanism of such super-Neptune or sub-Saturn kind of planets, that are too close to the host star, according to scientists.

## See also

* List of potentially habitable exoplanets
* List of exoplanet firsts
* List of exoplanetary host stars
* List of exoplanets discovered using the Kepler spacecraft
* List of planets observed during Kepler's K2 mission
* List of nearest terrestrial exoplanet candidates

## References

1. ↑ 1.0 1.1 1.2 1.3 Chakraborty, Abhijit et al. (8 June 2018). "Evidence of a Sub-Saturn around EPIC 211945201". The Astronomical Journal 156 (1). doi:10.3847/1538-3881/aac436. Bibcode: 2018AJ....156....3C.
2. ↑ Kokori, A. et al. (14 February 2023). "ExoClock Project. III. 450 New Exoplanet Ephemerides from Ground and Space Observations". The Astrophysical Journal Supplement Series 265 (1). doi:10.3847/1538-4365/ac9da4. Bibcode: 2023ApJS..265....4K. Vizier catalog entry
3. ↑ "EPIC 211945201 b | New World Atlas - Exoplanet Exploration: Planets Beyond our Solar System". https://exoplanets.nasa.gov/newworldsatlas/6307/epic-211945201-b/. [|permanent dead link|dead link}}]
4. ↑ "5 Ways to Find a Planet". https://exoplanets.nasa.gov/5-ways-to-find-a-planet/#/2.
5. ↑ Telechev, Anton. "Exoplorer: epic-211945201-b" (in en). http://exoplorer.org/en/exoplanets/epic-211945201-b.
6. ↑ "The Extrasolar Planet Encyclopaedia — HATS-36 b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/hats_36_b--6570/.

* v
* t
* e

2018 in space

* « 2017

2019 »

Space probe launches |

* TESS (lunar flyby; Apr 2018)
* InSight / Mars Cube One (mission to Mars; May 2018)
* Parker Solar Probe (solar space mission; Aug 2018)
* BepiColombo (mission to Mercury; Oct 2018)
* Chang'e 4 / Yutu-2 (mission to the Moon; Dec 2018)

Impact events|

* 2018 LA
* Kamchatka meteor

Selected NEOs|

* Asteroid close approaches
* 2010 WC9
* 2017 VR12
* 2017 YE5
* 2017 YZ1
* 2018 AH
* 2018 BD
* 2018 BF3
* 2018 CB
* 2018 CC
* 2018 CF2
* 2018 CL
* 2018 CN2
* 2018 CY2
* 2018 DV1
* 2018 GE3
* 2018 PD20
* 2018 LF16
* 2018 WV1
* (276033) 2002 AJ129
* (163899) 2003 SD220
* (505657) 2014 SR339

Exoplanets |

* Gliese 1132 c
* K2-141b
* K2-146b
* K2-148b
* K2-155d
* K2-229b
* K2-239b
* K2-239c
* K2-239d
* K2-288Bb
* Barnard's Star b
* EPIC 211945201 b
* HD 89345 b
* KELT-21b
* NGTS-3Ab

Discoveries|

* AT2018cow
* Novae (List)
* Carina
* Musca
* Perseus
* MACS J1149 Lensed Star 1
* Hyperion proto-supercluster
* 2015 TH367 (orbit announced)
* 2015 TG387 (orbit announced)
* 2017 OF69 (announced)
* 2018 VG18

Comets |

* C/2018 V1
* 46P/Wirtanen
* Hyperbolic comets
* C/2017 U7 (announced in 2018)
* C/2018 C2 (Lemmon)
* C/2018 F4 (PANSTARRS)

Space exploration|

* Hayabusa2 (asteroid Ryugu arrival; June 2018)
* OSIRIS-REx (asteroid Bennu arrival; Dec 2018)
* New Horizons (encounter with 486958 Arrokoth; Dec 2018 / Jan 2019)
* Dawn retirement
* Kepler retirement

* Category:2017 in space — Category:2018 in space — Category:2019 in space

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