Misplaced Pages

Kepler-438b

Approximate size comparison of Kepler-438b (right) with Earth
Discovery
Discovered by	Kepler spacecraft
Discovery date	2015
Detection method	Transit
Orbital characteristics
Semi-major axis	0.16600 AU (24,833,000 km)
Eccentricity	0.03+0.01 −0.03
Orbital period (sidereal)	35.23319 d
Inclination	89.860
Star	Kepler-438
Physical characteristics
Mean radius	1.12 (± 0.16) R🜨
Temperature	276 K (3 °C; 37 °F)

Kepler-438b (also known by its Kepler Object of Interest designation KOI-3284.01) is a confirmed near-Earth-sized exoplanet. It is likely rocky. It orbits on the inner edge of the habitable zone of a red dwarf, Kepler-438, about 460.2 light-years from Earth in the constellation Lyra. It receives 1.4 times our solar flux. The planet was discovered by NASA's Kepler spacecraft using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. NASA announced the confirmation of the exoplanet on 6 January 2015.

Characteristics

Mass, radius and temperature

Kepler-438b is an Earth-sized planet, an exoplanet that has a mass and radius close to that of Earth. It has a radius of 1.12 R_🜨, and an unknown mass. It has an equilibrium temperature of 276 K (3 °C; 37 °F), close to that of Earth.

Host star

The planet orbits a (M-type) red dwarf star named Kepler-438. The star has a mass of 0.54 M_☉ and a radius of 0.52 R_☉, both lower than those of the Sun by almost half. It has a surface temperature of 3748 K and is estimated to be about 4.4 billion years old, only 200 million years younger than the Sun and the Sun has a surface temperature of 5778 K.

The star's apparent magnitude, or how bright it appears from Earth's perspective, is 14.467. Therefore, it is too dim to be seen with the naked eye.

Orbit and possible moons

Kepler-438b orbits its parent star once every 35 days and 5 hrs It is likely tidally locked due to its close distance to its star. A search for exomoons by the Hunt for Exomoons with Kepler project around Kepler-438b placed a maximum mass of a hypothetical moon at 29% that of the planet.

Habitability

The planet was announced as orbiting within the habitable zone of Kepler-438, a region where liquid water could exist on the surface of the planet. However it has been found that this planet is subjected to powerful radiation activity from its parent star every 100 days, much more violent storms than the stellar flares emitted by the Sun and which would be capable of sterilizing life on Earth.

Researchers at the University of Warwick say that Kepler-438b is not habitable due to the large amount of radiation it receives. The question of what makes a planet habitable is much more complex than having a planet located at the right distance from its host star so that water can be liquid on its surface: various geophysical and geodynamical aspects, the radiation, and the host star's plasma environment can influence the evolution of planets and life, if it originated. The planet is more likely to resemble a larger and cooler version of Venus.

Discovery and follow-up studies

In 2009, NASA's Kepler spacecraft was completing observing stars on its photometer, the instrument it uses to detect transit events, in which a planet crosses in front of and dims its host star for a brief and roughly regular period of time. In this last test, Kepler observed 50000 stars in the Kepler Input Catalog, including Kepler-62; the preliminary light curves were sent to the Kepler science team for analysis, who chose obvious planetary companions from the bunch for follow-up at observatories. Observations for the potential exoplanet candidates took place between 13 May 2009 and 17 March 2012. After observing the respective transits, which for Kepler-438b occurred roughly every 35 days (its orbital period), it was eventually concluded that a planetary body was responsible for the periodic 35-day transits. The discovery, along with the planetary systems of the stars Kepler-442, Kepler-440 and Kepler-443 were announced on January 6, 2015.

At nearly 460 light-years (140 pc) distant, Kepler-438b is too far from Earth for either current telescopes, or even the next generation of planned telescopes, to accurately determine its mass or whether it has an atmosphere. The Kepler spacecraft can only focus on a small, fixed region of the sky, but the next generation of planet-hunting space telescopes, such as TESS and CHEOPS, will have more flexibility. Exoplanetary systems, with stars less distant than Kepler 438, can then be studied in tandem with the upcoming James Webb Space Telescope and ground-based observatories like the future Square Kilometer Array.

Notable Exoplanets – Kepler Space Telescope
Confirmed small exoplanets in habitable zones. (Kepler-62e, Kepler-62f, Kepler-186f, Kepler-296e, Kepler-296f, Kepler-438b, Kepler-440b, Kepler-442b) (Kepler Space Telescope; 6 January 2015).

See also

• Kepler-442b
• Kepler-452b
• List of potentially habitable exoplanets
• TrES-2b

References

1. ^ Clavin, Whitney; Chou, Felicia; Johnson, Michele (6 January 2015). "NASA's Kepler Marks 1,000th Exoplanet Discovery, Uncovers More Small Worlds in Habitable Zones". NASA. Retrieved 6 January 2015.
2. ^ Sample, Ian (7 January 2015). "Kepler 438b: Most Earth-like planet ever discovered could be home for alien life". The Guardian. Retrieved 7 January 2015.
3. ^ Torres, Guillermo; Kipping, David M.; Fressin, Francois; Caldwell, Douglas A.; Twicken, Joseph D.; Ballard, Sarah; Batalha, Natalie M.; Bryson, Stephen T.; Ciardi, David R.; Henze, Christopher E.; Howell, Steve B.; Isaacson, Howard T.; Jenkins, Jon M.; Muirhead, Philip S.; Newton, Elisabeth R.; Petigura, Erik A.; Barclay, Thomas; Borucki, William J.; Crepp, Justin R.; Everett, Mark E.; Horch, Elliott P.; Howard, Andrew W.; Kolbl, Rea; Marcy, Geoffrey W.; McCauliff, Sean; Quintana, Elisa V. (2015). "Validation of Twelve Small Kepler Transiting Planets in the Habitable Zone". The Astrophysical Journal. 800 (2): 99. arXiv:1501.01101. Bibcode:2015ApJ...800...99T. doi:10.1088/0004-637X/800/2/99. S2CID 8512655.
4. Staff (2015). "Planet Kepler-438 b". Extrasolar Planets Encyclopaedia. Retrieved 11 January 2015.
5. Northon, Karen (19 March 2015). "NASA's Kepler Uncovers More Small Worlds in Habitable Zones". NASA. Retrieved 29 December 2022.
6. Gilster, Paul (6 January 2015). "AAS: 8 New Planets in Habitable Zone". Centauri-dreams.org. Retrieved 9 January 2015.
7. Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
8. Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
9. "Kepler-438b: Astronomers Find Most Earth-Like Exoplanet Yet". Sci News. 8 January 2015. Retrieved 13 June 2016.
10. Kipping, D. M.; et al. (2014). "The Hunt for Exomoons with Kepler (HEK). IV. A Search for Moons around Eight M Dwarfs". The Astrophysical Journal. 784 (1): 28–41. arXiv:1401.1210. Bibcode:2014ApJ...784...28K. doi:10.1088/0004-637X/784/1/28. S2CID 119305398.
11. Perkins, Sid (2015). "Earth-like planet may be not so hospitable after all, thanks to blasts of radiation". Science. doi:10.1126/science.aad7455. ISSN 0036-8075.
12. 'Earth-like' Exoplanet Likely Not Habitable
13. Lammer, H.; Bredehöft, J. H.; Coustenis, A.; Khodachenko, M. L.; et al. (2009). "What makes a planet habitable?" (PDF). The Astronomy and Astrophysics Review. 17 (2): 181–249. Bibcode:2009A&ARv..17..181L. doi:10.1007/s00159-009-0019-z. S2CID 123220355. Archived from the original (PDF) on 2 June 2016. Retrieved 3 May 2016.
14. Siemion, Andrew P.V.; Demorest, Paul; Korpela, Eric; Maddalena, Ron J.; Werthimer, Dan; Cobb, Jeff; Langston, Glen; Lebofsky, Matt; Marcy, Geoffrey W.; Tarter, Jill (3 February 2013). "A 1.1 to 1.9 GHz SETI Survey of the Kepler Field: I. A Search for Narrow-band Emission from Select Targets". Astrophysical Journal. 767 (1): 94. arXiv:1302.0845. Bibcode:2013ApJ...767...94S. doi:10.1088/0004-637X/767/1/94. S2CID 119302350.

External links

• NASA – Mission overview.
• NASA – Kepler Discoveries – Summary Table.
• NASA – Kepler-438b at The NASA Exoplanet Archive.
• NASA – Kepler-438b at The Extrasolar Planets Encyclopaedia.
• Habitable Exolanets Catalog at UPR-Arecibo.

v t e 2015 in space
« 2014 2016 »
Space probe launches	Space probes SMAP (weather satellite; Jan 2015) LISA Pathfinder (technology demonstration; Dec 2015) Space observatories DSCOVR (weather satellite; Feb 2015) Astrosat (space telescope; Sep 2015)
Impact events	2015 Kerala meteoroid 2015 Thailand bolide WT1190F impact
Selected NEOs	Asteroid close approaches 2015 BP513 (357439) 2004 BL86 2015 AZ43 (523775) 2014 YB35 1566 Icarus 2015 HM10 2015 TC25 2015 TB145 2007 VE191 (33342) 1998 WT24 (85989) 1999 JD6 2015 SO2
Exoplanets	Aldebaran b evaporation of Gliese 436 b Gliese 1132 b HD 155233 b HD 164595 b HD 219134 b c d f g? h? HIP 11915 b K2-3d K2-18b K2-22b K2-24b K2-24c KELT-4Ab Kepler-438b Kepler-440b Kepler-442b Kepler-444 b c d e f Kepler-451b Kepler-452b Kepler-453b KOI-4878.01 LkCa 15 b spectrum of 51 Pegasi b WASP-121b Wolf 1061c
Discoveries	2015 BP519 US 708 EGS-zs8-1 (announced) WISE J224607.57−052635.0 1SWASP J093010.78+533859.5 ASASSN-15lh EGSY8p7 Tabby's Star 541132 Leleākūhonua VFTS 352 contact binary GW150914 (first observation of gravitational waves) GW151226
Comets	15P/Finlay C/2014 Q2 (Lovejoy) 88P/Howell C/2014 Q1 (PanSTARRS) C/2015 G2 (MASTER) C/2013 US10 (Catalina) 67P/Churyumov–Gerasimenko 10P/Tempel
Space exploration	Rosetta (orbiting comet 67P; Nov 2014 / Mar 2015) Dawn (Ceres orbit insertion; Mar 2015) MESSENGER (end of mission; Apr 2015) New Horizons (flyby of Pluto; Jul 2015) Akatsuki (Venus orbit insertion; Dec 2015)
Outer space portal Category:2014 in outer space — Category:2015 in outer space — Category:2016 in outer space

v t e Exoplanets
Planet Definition IAU Planetary science
Main topics	Exoplanet Exoplanet orbital and physical parameters Methods of detecting exoplanets Planetary system Planet-hosting stars
Sizes and types	Terrestrial Carbon planet Coreless planet Desert planet Dwarf planet Hycean planet Ice planet Iron planet (Super-Mercury) Lava planet Ocean world Mega-Earth Sub-Earth Super-Earth Gaseous Eccentric Jupiter Mini-Neptune (Gas dwarf) Helium planet Hot Jupiter Hot Neptune Gas giant Ice giant Super-Jupiter Super-Neptune Super-puff Ultra-hot Jupiter Ultra-hot Neptune Other types Blanet Brown dwarf Chthonian planet Circumbinary planet Circumtriple planet Disrupted planet Double planet Ecumenopolis Eyeball planet Giant planet Mesoplanet Planemo Planet/Brown dwarf boundary Planetesimal Protoplanet Pulsar planet Sub-brown dwarf Sub-Neptune Toroidal planet Ultra-cool dwarf Ultra-short period planet (USP)
Formation and evolution	Accretion Accretion disk Asteroid belt Circumplanetary disk Circumstellar disc Circumstellar envelope Cosmic dust Debris disk Detached object Disrupted planet Excretion disk Exozodiacal dust Extraterrestrial materials Extraterrestrial sample curation Giant-impact hypothesis Gravitational collapse Hills cloud Internal structure Interplanetary dust cloud Interplanetary medium Interplanetary space Interstellar cloud Interstellar dust Interstellar medium Interstellar space Kuiper belt List of interstellar and circumstellar molecules Merging stars Molecular cloud Nebular hypothesis Oort cloud Outer space Planetary migration Planetary system Planetesimal Planet formation Protoplanetary disk Ring system Rubble pile Sample-return mission Scattered disc Star formation
Systems	Exocomet Interstellar Exomoon Tidally detached Rogue planet Orbits Retrograde Trojan Mean-motion resonances Titius–Bode law
Host stars	A B Binary star Brown dwarfs F/Yellow-white dwarfs G/Yellow dwarfs Herbig Ae/Be K/Orange dwarfs M/Red dwarfs Pulsar Red giant Subdwarf B Subgiant T Tauri White dwarfs Yellow giants
Detection	Astrometry Direct imaging list Microlensing list Polarimetry Timing list Radial velocity list Transit method list Transit-timing variation
Habitability	Astrobiology Astrooceanography Circumstellar habitable zone Earth analog Extraterrestrial liquid water Galactic habitable zone Habitability of binary star systems Habitability of F-type main-sequence star systems Habitability of K-type main-sequence star systems Habitability of natural satellites Habitability of neutron star systems Habitability of red dwarf systems Habitability of yellow dwarf systems Habitable zone for complex life List of potentially habitable exoplanets Tholin Superhabitable planet
Catalogues	Nearby Habitable Systems Exoplanet Data Explorer Extrasolar Planets Encyclopaedia NASA Exoplanet Archive NASA Star and Exoplanet Database Open Exoplanet Catalogue
Lists	Exoplanetary systems Host stars Multiplanetary systems Stars with proto-planetary discs Exoplanets Discoveries Extremes Firsts Nearest Largest Heaviest Terrestrial candidates Kepler 1–500 501–1000 1001–1500 1501–2000 K2 Potentially habitable Proper names Discovered exoplanets by year before 2000 2000–2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024
Other	Carl Sagan Institute Exoplanet naming convention Exoplanet phase curves Exoplanetary Circumstellar Environments and Disk Explorer Extragalactic planet Extrasolar planets in fiction Geodynamics of terrestrial exoplanets Neptunian desert Nexus for Exoplanet System Science Planets in globular clusters Small planet radius gap Sudarsky's gas giant classification
Discoveries of exoplanets Search projects

• Astronomy
• Biology

• Exoplanets discovered by the Kepler space telescope
• Exoplanets discovered in 2015
• Exoplanets in the habitable zone
• Lyra
• Transiting exoplanets
• Near-Earth-sized exoplanets in the habitable zone