{{Short description|Hot Jupiter orbiting the star WASP-31}} {{use dmy dates|date=March 2018}} {{Infobox planet | name = WASP-31b | image = HotJupiter-Exoplanet-WASP-31b.jpg | caption = "Hot Jupiter" exoplanet WASP-31b (artist concept) <!-- DISCOVERY --> | discoverer = Anderson, D.R. et al.<ref name="AANDA-20110518"/> | discovery_site = WASP<ref name="EXO-20180302" /> | discovered = 2010<ref name="EXO-20180302" /> | discovery_method = Primary transit<ref name="EXO-20180302" /> <!-- DESIGNATIONS --> <!-- ORBITAL --> | apsis = astron | semimajor = {{val|0.04657|0.00034}} AU | eccentricity = 0<ref name="EXO-20180302" /> | period = {{val|3.40591|}}<ref name="EXO-20180302" /> d | inclination = {{val|84.54|0.027}}<ref name="EXO-20180302" /> | star = WASP-31<ref name="EXO-20180302" /> <!-- PHYS CHARS --> | mean_radius = {{val|1.537|0.06}}<ref name="EXO-20180302" /> {{Jupiter radius|link=y}} | mass = {{val|0.478|0.03}}<ref name="EXO-20180302" /> {{Jupiter mass|link=y}} <!-- ATMOSPHERE --> <!-- NOTES --> }} '''WASP-31b''' is a low-density (puffy) "hot Jupiter" extrasolar planet orbiting the metal-poor (63% of solar metallicity) dwarf star WASP-31.<ref name="AANDA-20110518" /> The exoplanet was discovered in 2010 by the WASP project.<ref name="EXO-20180302" /><ref name="AANDA-20110518" /> WASP-31b is in the constellation of Crater,<ref name="DJM-2018" /> and is about 1305 light-years<ref name="KC-2018" /> (light travel distance) from Earth.<ref name="EXO-20180302" />
==Characteristics== WASP-31b is a low-density (puffy) "hot Jupiter" exoplanet with a mass about 0.48 times that of Jupiter and a radius about 1.55 times that of Jupiter.<ref name="EXO-20180302" /><ref name="AANDA-20110518" /> The planetary atmosphere has indeed the largest scale height, equal to 1150km, among exoplanets with measurable atmospheres as at 2021.<ref>{{citation|arxiv=2103.07185|year=2021|title=Evidence for disequilibrium chemistry from vertical mixing in hot Jupiter atmospheres|doi=10.1051/0004-6361/202039708 |last1=Baxter |first1=Claire |last2=Désert |first2=Jean-Michel |last3=Tsai |first3=Shang-Min |last4=Todorov |first4=Kamen O. |last5=Bean |first5=Jacob L. |last6=Deming |first6=Drake |last7=Parmentier |first7=Vivien |last8=Fortney |first8=Jonathan J. |last9=Line |first9=Michael |last10=Thorngren |first10=Daniel |last11=Pierrehumbert |first11=Raymond T. |last12=Burrows |first12=Adam |last13=Showman |first13=Adam P. |journal=Astronomy & Astrophysics |volume=648 |pages=A127 |s2cid=232222174 }}</ref>
The exoplanet orbits WASP-31, its host star, every 3.4 days.<ref name="EXO-20180302" /> [[File:Clear to cloudy hot Jupiters.jpg|thumb|center|400px|{{center|Comparison of "hot Jupiter" exoplanets, including WASP-31b<br>(top row; 3rd from left) (artist concept)}} <br>From top left to lower right: WASP-12b, WASP-6b, WASP-31b, WASP-39b, HD 189733b, HAT-P-12b, WASP-17b, WASP-19b, HAT-P-1b and HD 209458b.]] In 2012, it was found from the Rossiter–McLaughlin effect that WASP-31b is orbiting the parent star in a prograde direction.<ref>{{cite journal|arxiv=1203.4971|doi=10.1111/j.1365-2966.2012.20973.x|title=Rossiter-Mc ''Laughlin'' effect measurements for WASP-16, WASP-25 and WASP-31★|year=2012|last1=Brown|first1=D. J. A.|last2=Cameron|first2=A. Collier|last3=Anderson|first3=D. R.|last4=Enoch|first4=B.|last5=Hellier|first5=C.|last6=Maxted|first6=P. F. L.|last7=Miller|first7=G. R. M.|last8=Pollacco|first8=D.|last9=Queloz|first9=D.|last10=Simpson|first10=E.|last11=Smalley|first11=B.|last12=Triaud|first12=A. H. M. J.|last13=Boisse|first13=I.|last14=Bouchy|first14=F.|last15=Gillon|first15=M.|last16=Hébrard|first16=G.|journal=Monthly Notices of the Royal Astronomical Society|volume=423|issue=2|pages=1503–1520|doi-access=free |bibcode=2012MNRAS.423.1503B|s2cid=53445367 }}</ref> The projected inclination of the WASP-31 star rotational axis relative to the planetary orbit is close to zero, with a value of −0.09{{±|0.31|0.32}} degrees cited in a 2026 study.<ref>{{cite arxiv |last1=Steiner |first1=M. |display-authors=etal |title=Precise measurement of WASP-31 b's Rossiter-McLaughlin effect and characterization of the planet transmission spectra |eprint=2602.15501 |class=astro-ph.EP |year=2026}}</ref><!--accepted for publication in A&A, replace when available--> The spectroscopic study in 2014 revealed that WASP-31b has a dense cloud deck overlaid by a hazy atmosphere.<ref>{{Cite web|url=https://wasp-planets.net/2014/10/30/the-atmosphere-of-hot-jupiter-exoplanet-wasp-31b/|title=The atmosphere of hot-Jupiter exoplanet WASP-31b|date=30 October 2014}}</ref> WASP-31b was also reported to have significant amounts of potassium in its upper atmosphere, but the detection of potassium was refuted in 2015.<ref>{{cite journal|arxiv=1810.03693|doi=10.1093/mnras/sty2722|title=Revisiting the potassium feature of WASP-31b at high resolution|year=2019|last1=Gibson|first1=Neale P.|last2=De Mooij|first2=Ernst J W.|last3=Evans|first3=Thomas M.|last4=Merritt|first4=Stephanie|last5=Nikolov|first5=Nikolay|last6=Sing|first6=David K.|last7=Watson|first7=Chris|journal=Monthly Notices of the Royal Astronomical Society|volume=482|issue=1|pages=606–615|doi-access=free |bibcode=2019MNRAS.482..606G}}</ref> The potassium detection discrepancy was resolved in 2020 with the improved cloud deck model,<ref>{{Cite journal|url=https://www.cambridge.org/core/journals/proceedings-of-the-international-astronomical-union/article/modeling-the-transmission-spectra-of-wasp31b/025747496F5161DB59AF7FD51C40913D|title=Modeling the Transmission Spectra of WASP-31b|first1=J.|last1=Chouqar|first2=M. L.|last2=Morales|first3=A.|last3=Daassou|first4=A.|last4=Jabiri|first5=Z.|last5=Benkhaldoun|date=27 August 2018|journal=Proceedings of the International Astronomical Union|volume=14|issue=S345|pages=383–385|via=Cambridge University Press|doi=10.1017/S1743921319002953|url-access=subscription}}</ref> with the best fit being a very small amount of water over clouds and no potassium at all.<ref>{{citation|arxiv=2009.08472|title=ACCESS: Confirmation of No Potassium in the Atmosphere of WASP-31b|year=2020|doi=10.3847/1538-3881/abb806 |last1=McGruder |first1=Chima D. |last2=López-Morales |first2=Mercedes |last3=Espinoza |first3=Néstor |last4=Rackham |first4=Benjamin V. |last5=Apai |first5=Dániel |last6=Jordán |first6=Andrés |last7=Osip |first7=David J. |last8=Alam |first8=Munazza K. |last9=Bixel |first9=Alex |last10=Fortney |first10=Jonathan J. |last11=Henry |first11=Gregory W. |last12=Kirk |first12=James |last13=Lewis |first13=Nikole K. |last14=Rodler |first14=Florian |last15=Weaver |first15=Ian C. |journal=The Astronomical Journal |volume=160 |issue=5 |page=230 |bibcode=2020AJ....160..230M |s2cid=221802525 |doi-access=free }}</ref>
Reanalysis of planetary spectroscopic data in 2020 has revealed the presence of chromium monohydride besides water.<ref>{{citation|arxiv=2011.10558|title=Evidence for chromium hydride in the atmosphere of hot Jupiter WASP-31b|year=2021|doi=10.1051/0004-6361/202039509 |last1=Braam |first1=Marrick |last2=Van Der Tak |first2=Floris F. S. |last3=Chubb |first3=Katy L. |last4=Min |first4=Michiel |journal=Astronomy & Astrophysics |volume=646 |pages=A17 |bibcode=2021A&A...646A..17B |s2cid=227118876 }}</ref>
==See also== * WASP-6b * WASP-12b * WASP-17b * WASP-19b * WASP-39b * WASP-121b
==References== <references>
<ref name="AANDA-20110518">{{cite journal |last=Anderson |first=D.R. |display-authors=etal |title=WASP-31b: a low-density planet transiting a metal-poor, late-F-type dwarf star |url=https://www.aanda.org/articles/aa/pdf/2011/07/aa16208-10.pdf |journal=Astronomy & Astrophysics |volume=531 |pages=A60 |arxiv=1011.5882 |bibcode=2011A&A...531A..60A |doi=10.1051/0004-6361/201016208|year=2011 |s2cid=20154835 }}</ref>
<ref name="DJM-2018">{{cite web |author=DJM |title=Finding the constellation which contains given sky coordinates |url=http://djm.cc/constellation.html |date=2018 |work=djm.cc |accessdate=2 March 2018 }}</ref>
<ref name="EXO-20180302">{{cite encyclopedia |author=Staff |title=Planet WASP-31 b |url=https://exoplanet.eu/catalog/wasp_31_b--707/ |date=2018 |encyclopedia=Extrasolar Planets Encyclopaedia |access-date=2 March 2018 }}</ref>
<ref name="KC-2018">{{cite web |author=Kyle |title=Convert Parsecs to Light Years |url=http://www.kylesconverter.com/length/parsecs-to-light-years |date=2018 |work=KylesConverter.com |accessdate=2 March 2018 }}</ref>
</references>
==External links== {{commonscat-inline|WASP-31 b|WASP-31b}} {{Crater (constellation)}}{{portal bar|Astronomy|Space}} {{Sky|11|17|45.0|-|19|03|17}}
Category:Exoplanets discovered by WASP Category:Exoplanets discovered in 2010 Category:Giant planets Category:Hot Jupiters Category:Crater (constellation)