View source for Astronomy:K2-72d

{{short description|Extrasolar planet}}
{{Infobox planet
| name                     = K2-72d
<!-- DISCOVERY           -->
| discovered               = July 18, 2016
| discovery_method         = Transit
<!-- DESIGNATIONS        -->
<!-- ORBITAL             --> 
| apsis                    = astron
| semimajor                = {{convert|0.0461|±|0.0058|AU|km|abbr=on}}<ref name=NASA/>
| period                   = 7.7599±0.0014<ref name=NASA/> [[Day|d]]
| star                     = [[Astronomy:K2-72|K2-72]]<ref name=NASA>{{cite web
 | url=http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=k2-72+d&type=CONFIRMED_PLANET
 | title=K2-72d CONFIRMED PLANET OVERVIEW PAGE
 | work=NASA Exoplanet Archive
 | access-date=2016-07-18
}}</ref>
<!-- PHYS CHARS          --> 
| mean_radius              = 0.73±0.20 <ref name=NASA/> {{Earth radius|link=y}}
<!-- ATMOSPHERE          --> 
<!-- NOTES               --> 
}}
'''K2-72d''' is a small [[Astronomy:Exoplanet|exoplanet]] orbiting around the [[Astronomy:Red dwarf|red dwarf]] [[Astronomy:Star|star]] [[Astronomy:K2-72|K2-72]] approximately 227.7 light-years away. K2-72d completes an orbit in 7.8 days, and it has a radius of only 73% of that of the [[Astronomy:Earth|Earth]].

==Host star==
{{main|Astronomy:K2-72}}
The planet orbits a ([[Astronomy:Stellar classification#Class M|M-type]]) [[Astronomy:Red dwarf|red dwarf]] [[Astronomy:Star|star]] named [[Astronomy:K2-72|K2-72]], orbited by a total of four planets, of which [[Astronomy:K2-72e|K2-72e]] has the longest orbital period. The star has a mass of 0.27 {{solar mass}} and a radius of 0.33 {{solar radius}}. It has a temperature of 3360 K and its age is unknown. In comparison, the [[Astronomy:Sun|Sun]] is 4.6 billion years old<ref>{{cite web |url=http://www.universetoday.com/18237/how-old-is-the-sun/ |title=How Old is the Sun? |first=Fraser |last=Cain |date=16 September 2008 |publisher=Universe Today |access-date=19 February 2011}}</ref> and has a surface temperature of 5778 K.<ref>{{cite web |url=http://www.universetoday.com/18092/temperature-of-the-sun/ |title=Temperature of the Sun |first=Fraser |last=Cain |date=15 September 2008 |publisher=Universe Today |access-date=19 February 2011}}</ref>

The star's [[Astronomy:Apparent magnitude|apparent magnitude]], or how bright it appears from Earth's perspective, is 15.309. Therefore, it is too dim to be seen with the naked eye and can only be observed with a telescope. 

== Discovery ==
The planet, along with the other three planets in the K2-72 system, were announced in mid-July 2016 as part of the new results from the second mission of the [[Engineering:Kepler (spacecraft)|Kepler]] spacecraft.

==References==
{{Reflist}}


{{2016 in space}}
{{Aquarius (constellation)}}

{{DEFAULTSORT:K2-72d}}
[[Category:Transiting exoplanets]]


{{exoplanet stub}}
[[Category:Aquarius (constellation)]]

{{Sourceattribution|K2-72d}}