WASP-76b
{{short description|Hot Jupiter orbiting WASP-76}}
{{Infobox planet
| name = WASP-76b
| image = File:WASP-76bEffetdeGloire.jpg
| caption = Artistic image of WASP-76b, showing its possible glory effect
| discoverer = R.G. West et al. (SuperWASP)
| discovered = October 21, 2013
| discovery_method = Transit (including secondary eclipses)
| apsis = astron
| aphelion =
| perihelion =
| semimajor = {{val|0.03277|0.00078|ul=AU}}
| eccentricity = 0{{Cite encyclopedia |date=March 7, 2022 |title=Planet WASP-76 b |url=https://exoplanet.eu/catalog/wasp_76_b--1420/ |archive-url=https://web.archive.org/web/20231222054756/https://exoplanet.eu/catalog/wasp_76_b--1420/ |archive-date=December 22, 2023 |access-date=Aug 28, 2022 |encyclopedia=Extrasolar Planets Encyclopaedia |url-status=live }}
| period = {{val|1.80988122|(46)}} days
| inclination = {{val|87.58|0.79|0.59|u=deg}}
| arg_peri =
| star = WASP-76
| mean_radius = {{val|1.802|0.042|ul=Jupiter radius}}
| mass = {{val|0.921|0.032|ul=Jupiter mass}}
| single_temperature = {{val|2190|35|ul=K}}
}}{{Use mdy dates|date=March 2022}}File:Artist’s impression of the night side of WASP-76b.jpg
WASP-76b is an exoplanet classified as a Hot Jupiter. It is located in the constellation Pisces and orbits its host star, WASP-76, at a distance of approximately {{convert|0.033|AU|e6km e6mi|abbr=unit}}. Its orbital period is approximately 1.8 days, and its mass is about 0.92 times that of Jupiter.{{cite web |date=n.d. |title=WASP-76 b |url=https://exoplanets.nasa.gov/exoplanet-catalog/1833/wasp-76-b/ |access-date=March 21, 2022 |work=Exoplanet Exploration: Planets Beyond our Solar System |publisher=NASA}}{{cite web |last1=Ehrenreich |first1=David |last2=Pepe |first2=Francesco |last3=Osorio |first3=María Rosa Zapatero |last4=Figueira |first4=Pedro |last5=Santos |first5=Nuno C. |last6=Cristiani |first6=Stefano |last7=Ferreira |first7=Bárbara |display-authors=etal |date=11 March 2020 |title=ESO Telescope Observes Exoplanet Where It Rains Iron |url=https://www.eso.org/public/news/eso2005/ |access-date=March 21, 2022 |work=European Southern Observatory}}{{cite news |last= |date=March 11, 2020 |title=On a faraway planet, it's cloudy with a chance of liquid iron rain |url=https://www.nbcnews.com/science/space/faraway-planet-it-s-cloudy-chance-liquid-iron-rain-n1156016 |access-date=May 3, 2020 |work=NBC News |agency=Reuters}} The discovery of WASP-76b took place on October 21, 2013; as of 2022, it is the only known planet in the WASP-76 system. The equilibrium temperature of WASP-76b is estimated to be around {{convert|2,190|K|C F}}, However, the measured daytime temperature is higher, reaching approximately {{convert|2,500|±|200|K|C F}}.{{cite journal |last1=Zhou |first1=G. |last2=Bayliss |first2=D. D. R. |last3=Kedziora-Chudczer |first3=L. |last4=Tinney |first4=C. G. |last5=Bailey |first5=J. |last6=Salter |first6=G. |last7=Rodriguez |first7=J. |display-authors=2 |date=December 11, 2015 |orig-date=October 16, 2015 |title=Secondary eclipse observations for seven hot-Jupiters from the Anglo-Australian Telescope |url=https://academic.oup.com/mnras/article/454/3/3002/1200704?login=false |journal=Monthly Notices of the Royal Astronomical Society |volume=454 |issue=3 |pages=3002–3019 |arxiv=1509.04147 |bibcode=2015MNRAS.454.3002Z |doi=10.1093/mnras/stv2138 |doi-access=free |s2cid=84835437 |access-date=March 21, 2022 |via=Oxford Academic}}
Atmospheric composition
Data collected from the Hubble and Spitzer Space Telescopes have provided evidence of titanium oxide and small amounts of water within the planet's atmosphere.{{Cite journal |last1=Fu |first1=Guangwei |last2=Deming |first2=Drake |last3=Lothringer |first3=Joshua |last4=Nikolov |first4=Nikolay |last5=Sing |first5=David K. |last6=Kempton |first6=Eliza M.-R. |last7=Ih |first7=Jegug |last8=Evans |first8=Thomas M. |last9=Stevenson |first9=Kevin |last10=Wakeford |first10=H. R. |last11=Rodriguez |first11=Joseph E. |display-authors=2 |date=August 17, 2021 |title=The Hubble PanCET Program: Transit and Eclipse Spectroscopy of the Strongly Irradiated Giant Exoplanet WASP-76b |journal=The Astronomical Journal |volume=162 |issue=3 |pages=108 |arxiv=2005.02568 |bibcode=2021AJ....162..108F |doi=10.3847/1538-3881/ac1200 |issn=0004-6256 |s2cid=218517004 |doi-access=free}} Further analysis using higher-resolution spectra has revealed the presence of ionized elements such as lithium, sodium, magnesium, calcium, manganese, potassium, and iron.{{Cite journal |last1=Tabernero |first1=H. M. |last2=Osorio |first2=M. R. Zapatero |last3=Allart |first3=R. |last4=Borsa |first4=F. |last5=Casasayas-Barris |first5=N. |last6=Demangeon |first6=O. |last7=Ehrenreich |first7=D. |last8=Lillo-Box |first8=J. |last9=Lovis |first9=C. |last10=Pallé |first10=E. |last11=Sousa |first11=S. G. |display-authors=2 |date=19 February 2021 |title=ESPRESSO high-resolution transmission spectroscopy of WASP-76 b |url=https://www.aanda.org/articles/aa/full_html/2021/02/aa39511-20/aa39511-20.html |journal=Astronomy & Astrophysics |volume=646 |at=17 |arxiv=2011.12197 |bibcode=2021A&A...646A.158T |doi=10.1051/0004-6361/202039511 |issn=0004-6361 |s2cid=227151361 |access-date=May 24, 2022}} The existence of calcium was confirmed by the Gemini North Observatory in 2021;{{Cite journal |last1=Casasayas-Barris |first1=N. |last2=Orell-Miquel |first2=J. |last3=Stangret |first3=M. |last4=Nortmann |first4=L. |last5=Yan |first5=F. |last6=Oshagh |first6=M. |last7=Palle |first7=E. |last8=Sanz-Forcada |first8=J. |last9=López-Puertas |first9=M. |last10=Nagel |first10=E. |last11=Luque |first11=R. |display-authors=2 |date=27 October 2021 |title=CARMENES detection of the Ca II infrared triplet and possible evidence of He I in the atmosphere of WASP-76b |url=https://www.aanda.org/articles/aa/full_html/2021/10/aa41669-21/aa41669-21.html |journal=Astronomy & Astrophysics |volume=654 |at=20 |arxiv=2109.00059 |doi=10.1051/0004-6361/202141669 |s2cid=237376656 |issn=0004-6361 |access-date=May 24, 2022}}{{Cite journal |last1=Deibert |first1=Emily K. |last2=de Mooij |first2=Ernst J. W. |last3=Jayawardhana |first3=Ray |last4=Turner |first4=Jake D. |last5=Ridden-Harper |first5=Andrew |last6=Fossati |first6=Luca |last7=Hood |first7=Callie E. |last8=Fortney |first8=Jonathan J. |last9=Flagg |first9=Laura |last10=MacDonald |first10=Ryan |last11=Allart |first11=Romain |display-authors=2 |date=September 28, 2021 |title=Detection of Ionized Calcium in the Atmosphere of the Ultra-hot Jupiter WASP-76b |journal=The Astrophysical Journal Letters |volume=919 |issue=2 |pages=L15 |no-pp=y |arxiv=2109.04373 |doi=10.3847/2041-8213/ac2513 |bibcode=2021ApJ...919L..15D |s2cid=237452713 |issn=2041-8205 |doi-access=free }}{{Cite web |last=News Staff |date=October 13, 2022 |title=Barium Detected in Atmospheres of Two Ultrahot Jupiters |url=https://www.sci.news/astronomy/exoplanetary-barium-11288.html |access-date=2022-10-15 |website=Sci News}} in 2022, barium was also detected.{{Cite journal |last1=Azevedo Silva |first1=T. |last2=Demangeon |first2=O. D. S. |last3=Santos |first3=N. C. |last4=Allart |first4=R. |last5=Borsa |first5=F. |last6=Cristo |first6=E. |last7=Esparza-Borges |first7=E. |last8=Seidel |first8=J. V. |last9=Palle |first9=E. |last10=Sousa |first10=S. G. |last11=Tabernero |first11=H. M. |last12=Zapatero Osorio |first12=M. R. |last13=Cristiani |first13=S. |last14=Pepe |first14=F. |last15=Rebolo |first15=R. |display-authors=2 |date=13 October 2022 |title=Detection of barium in the atmospheres of the ultra-hot gas giants WASP-76b and WASP-121b: Together with new detections of Co and Sr+ on WASP-121b |url=https://www.aanda.org/articles/aa/full_html/2022/10/aa44489-22/aa44489-22.html |journal=Astronomy & Astrophysics |volume=666 |issue=L10 |at=21 |doi=10.1051/0004-6361/202244489 |issn=0004-6361|arxiv=2210.06892 |bibcode=2022A&A...666L..10A }}
The atmosphere of WASP-76b is characterized as cloudy, predominantly grey, and exhibits significant thermal incandescence.{{cite journal |last1=Edwards |first1=Billy |last2=Changeat |first2=Quentin |last3=Baeyens |first3=Robin |last4=Tsiaras |first4=Angelos |last5=Al-Refaie |first5=Ahmed |last6=Taylor |first6=Jake |author7=Kai Hou Yip |author8=Michelle Fabienne Bieger |last9=Blain |first9=Doriann |last10=Gressier |first10=Amelie |last11=Guilluy |first11=Gloria |display-authors=2 |date=June 9, 2020 |title=ARES I: WASP-76 b, A Tale of Two HST Spectra* |journal=The Astronomical Journal |volume=160 |issue=1 |page=8 |arxiv=2005.02374 |bibcode=2020AJ....160....8E |doi=10.3847/1538-3881/ab9225 |author12=Adam Yassin Jaziri |last13=Kiefer |first13=Flavien |last14=Modirrousta-Galian |first14=Darius |last15=Morvan |first15=Mario |last16=Mugnai |first16=Lorenzo V. |last17=Pluriel |first17=William |last18=Poveda |first18=Mathilde |last19=Skaf |first19=Nour |last20=Whiteford |first20=Niall |last21=Wright |first21=Sam |last22=Zingales |first22=Tiziano |last23=Charnay |first23=Benjamin |last24=Drossart |first24=Pierre |last25=Leconte |first25=Jeremy |last26=Venot |first26=Olivia |last27=Waldmann |first27=Ingo |last28=Beaulieu |first28=Jean-Philippe |s2cid=218502668 |doi-access=free }}
In April 2024, it was suggested that a glory effect in the atmosphere of WASP-76b might be responsible for the observed increase in brightness of its eastern terminator zone. If this interpretation could be confirmed, it would become the first extrasolar glory-like phenomenon to be discovered.{{Cite web |last=European Space Agency |date=April 5, 2024 |title=Astronomers detect potential 'glory effect' on a hellish distant world for the first time |url=https://phys.org/news/2024-04-astronomers-potential-glory-effect-hellish.html |access-date=2024-04-07 |website=phys.org}}{{cite news |last=Strickland |first=Ashley |title=Scientists spot 'glory effect' on a world beyond our solar system for the first time |url=https://www.cnn.com/2024/04/19/world/rainbow-glory-exoplanet-scn/index.html |date=19 April 2024 |work=CNN |url-status=live |archiveurl=https://archive.today/20240419203336/https://www.cnn.com/2024/04/19/world/rainbow-glory-exoplanet-scn/index.html |archivedate=19 April 2024 |accessdate=20 April 2024 }}
= Iron rain =
In March 2020, an initial spectroscopic analysis revealed the presence of neutral iron in the atmosphere of WASP-76b. The conditions required for the vaporization and condensation of neutral iron were determined to be a temperature of {{convert|2,400|C|K F|sigfig=2}} and a lower temperature of {{convert|1,400|C|K F|sigfig=2}} for condensation. Under these specific temperature conditions, neutral iron could potentially precipitate like liquid rain.{{cite news |author=Amos |first=Jonathan |date=11 March 2020 |title=Wasp-76b: The exotic inferno planet where it 'rains iron' |work=BBC News |url=https://www.bbc.com/news/science-environment-51828871 |access-date=May 3, 2020}}
In May 2020, the Hubble Space Telescope discovered that the previous spectrum of WASP-76b had been distorted by the light from a companion star. Subsequently, an updated atmospheric model was developed using the most recent spectrum data. The revised model indicates the presence of a cloudy hydrogen-helium envelope and suggests the absence of previously reported neutral iron, including "iron rain."{{cite journal |last1=Lothringer |first1=Joshua D. |last2=Fu |first2=Guangwei |last3=Sing |first3=David K. |last4=Barman |first4=Travis S. |display-authors=2 |date=July 21, 2020 |title=UV Exoplanet Transmission Spectral Features as Probes of Metals and Rainout |journal=The Astrophysical Journal |volume=898 |issue=1 |pages=L14 |arxiv=2005.02528 |bibcode=2020ApJ...898L..14L |doi=10.3847/2041-8213/aba265 |s2cid=218516764 |doi-access=free }} Additionally, only upper limits on the presence of titanium and vanadium oxides were detected. By 2021, the controversy surrounding the presence of iron condensation had been resolved by demonstrating that the observed signal may also be due to temperature variations between different parts of the planet. However, existing data is insufficient to definitively distinguish between these two scenarios.{{Cite journal |last1=Wardenier |first1=Joost P |last2=Parmentier |first2=Vivien |last3=Lee |first3=Elspeth K H |last4=Line |first4=Michael R |last5=Gharib-Nezhad |first5=Ehsan |display-authors=2 |date=June 26, 2021 |title=Decomposing the iron cross-correlation signal of the ultra-hot Jupiter WASP-76b in transmission using 3D Monte Carlo radiative transfer |url=https://academic.oup.com/mnras/article/506/1/1258/6309906?login=false |journal=Monthly Notices of the Royal Astronomical Society |volume=506 |issue=1 |pages=1258–1283 |arxiv=2105.11034 |doi=10.1093/mnras/stab1797 |doi-access=free |issn=0035-8711 |access-date=May 24, 2022}}
Based on planetary atmospheric circulation models for WASP-76b, it is suggested that dense cloud layers composed of aluminum oxide, neutral iron, or magnesium orthosilicate may form. However, significant condensation of iron on the night side of the planet is not indicated by the available data.{{Cite journal |last1=Savel |first1=Arjun B. |last2=Kempton |first2=Eliza M.-R. |last3=Malik |first3=Matej |last4=Komacek |first4=Thaddeus D. |last5=Bean |first5=Jacob L. |last6=May |first6=Erin M. |last7=Stevenson |first7=Kevin B. |last8=Mansfield |first8=Megan |last9=Rauscher |first9=Emily |display-authors=2 |date=February 15, 2022 |orig-date=February 10, 2022 |title=No Umbrella Needed: Confronting the Hypothesis of Iron Rain on WASP-76b with Post-processed General Circulation Models |journal=The Astrophysical Journal |publisher=American Astronomical Society |volume=926 |issue=1 |pages=85 |arxiv=2109.00163 |bibcode=2022ApJ...926...85S |doi=10.3847/1538-4357/ac423f |issn=0004-637X |s2cid=237372235 |doi-access=free}}
Possible exomoon
It has been speculated that a possible hot evaporating exomoon orbiting around WASP-76b{{cite journal |last1=Seidel |first1=J.V. |last2=Ehrenreich |first2=D. |last3=Wyttenbach |first3=A. |last4=Allart |first4=R. |last5=Lendl |first5=M. |last6=Pino |first6=L. |last7=Bourrier |first7=V. |last8=Cegla |first8=H.M. |last9=Lovis |first9=C. |last10=Barrado |first10=D. |last11=Bayliss |first11=D. |last12=Astudillo-Defru |first12=N. |last13=Deline |first13=A. |last14=Fisher |first14=C. |last15=Heng |first15=K. |last16=Joseph |first16=R. |last17=Lavie |first17=B. |last18=Melo |first18=C. |last19=Pepe |first19=F. |last20=Segransan |first20=D. |last21=Udry |first21=S. |title=Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)★ II. A broadened sodium feature on the ultra-hot giant WASP-76b |journal=Astronomy & Astrophysics |date=27 March 2019 |volume=623 |page=A166 |doi=10.1051/0004-6361/201834776|arxiv=1902.00001 |bibcode=2019A&A...623A.166S |s2cid=119348582 }} could be consistent with an extrasolar toroidal atmosphere.{{cite journal |last1=Johnson |first1=Robert E. |last2=Huggins |first2=Patrick |title=Toroidal Atmospheres around Extrasolar Planets |journal=Publications of the Astronomical Society of the Pacific |date=August 2006 |volume=118 |issue=846 |pages=1136–1143 |doi=10.1086/506183|arxiv=astro-ph/0605655 |bibcode=2006PASP..118.1136J |s2cid=16201558 }}