View source for Astronomy:GJ 3470 b

{{short description|Hot Neptune orbiting GJ 3470}}
{{Infobox planet
| name = GJ 3470 b / Phailinsiam
| image = GJ3470b.jpg
| caption = Size comparison of GJ 3470 b with Earth.
<!-- DISCOVERY           -->
| discovery_ref = <ref name="Bonfils2012"/>
| discoverer = X. Bonfils et al.
| discovered = 2012
| discovery_method = Radial velocity
<!-- DESIGNATIONS        -->
| alt_names = Phailinsiam<ref name="NEW2022"/>
<!-- ORBITAL             -->
| orbit_ref = <ref name="Awiphan2016"/>
| apsis = astron
| semimajor = {{val|0.0355|0.0019|ul=AU}}
| eccentricity = {{val|0.114|0.052|0.051}}<ref name="Kosiarek2019"/>
| period = {{val|3.33665240|(14)|ul=d}}<ref name="Kokori2023"/>
| inclination = {{val|89.13|0.26|0.34|u=deg}}
| star = [[Astronomy:GJ 3470|GJ 3470]]
<!-- PHYS CHARS          -->
| physical_ref = <ref name="Awiphan2016"/>
| mean_radius = {{val|4.57|0.18|ul=Earth radius}}
| mass = {{val|13.9|1.5|ul=Earth mass}}
| density = {{val|0.80|0.13|ul=g/cm3}}
| single_temperature = {{val|615|16|ul=K}}<ref name="Kosiarek2019"/>
<!-- ATMOSPHERE          -->
<!-- NOTES               -->}}
'''GJ 3470 b''' (occasionally '''Gliese 3470 b''', formally named '''Phailinsiam'''<ref name="NEW2022"/>) is an [[Astronomy:Exoplanet|exoplanet]] orbiting the star [[Astronomy:GJ 3470|GJ 3470]], located in the constellation [[Unsolved:Cancer (astrology)|Cancer]]. With a mass of just under 14 Earth-masses and a radius approximately 4.3 times that of Earth's, it is likely something akin to [[Astronomy:Neptune|Neptune]] despite the initially strong belief that the planet was not covered in clouds like the gas giants in the [[Astronomy:Solar System|Solar System]].{{citation needed|date=April 2023}}

The orbit of GJ 3470 b is strongly inclined to the equatorial plane of the parent star, with misalignment equal to 97{{±|16|11}}°.<ref name="Stefansson2022"/>

==Nomenclature==
In August 2022, this planet and its host star were included among 20 systems to be named by the third [[Astronomy:NameExoWorlds|NameExoWorlds]] project.<ref>{{cite web |url=https://www.nameexoworlds.iau.org/2022exoworlds |title=List of ExoWorlds 2022 |date=8 August 2022 |website=nameexoworlds.iau.org |publisher=[[Organization:International Astronomical Union|IAU]] |access-date=27 August 2022}}</ref> The approved names, proposed by a team from Thailand, were announced in June 2023. GJ 3470 b is named '''Phailinsiam''' and its host star is named '''Kaewkosin''', after names of precious stones in the [[Social:Thai language|Thai language]].<ref name="NEW2022"/>

== Atmosphere ==
The atmosphere of GJ 3470 b is one of the best spectroscopically characterized among all exoplanets.

The exoplanet's atmosphere was first observed by researchers Akihiko Fukui, Norio Narita and Kenji Kuroda at the University of Tokyo in 2013, and afterwards, Fukui commented, "Suppose the atmosphere consists of hydrogen and helium, the mass of the atmosphere would be 5–20% of the total mass of the planet. Comparing that to the fact that the mass of Earth's atmosphere is about one ten-thousandth of a percent (0.0001%) of the total mass of the Earth, this planet has a considerably thick atmosphere."<ref name="Fukui2013"/> In 2013, by means of [[Astronomy:Large Binocular Telescope|Large Binocular Telescope]] observations, with the LBC Blue and Red cameras, a team reported the detection of [[Physics:Rayleigh scattering|Rayleigh scattering]] in the atmosphere of this planet.<ref name="Nascimbeni2013"/> In 2015 a team using the Las Cumbres Observatory Global Telescope (LCOGT) network confirmed this finding. In the Las Cumbres researchers' paper published in The Astrophysical Journal, they conclude that the most plausible explanation for the scattering effect to be an atmosphere made predominantly of hydrogen and helium, causing the exoplanet to be veiled by dense clouds and hazes.<ref name="Dragomir2015"/> It is thought that the planet would appear blue to the human eye due to this scattering.

In 2017–2019, the primary hydrogen atmosphere with overall low metallicity, depleted methane and traces of water was characterized.<ref name="Chen2017"/><ref name="Benneke2019"/> It is likely filling an entire [[Physics:Roche lobe|Roche lobe]] of the planet.<ref name="Bourrier2018"/> In 2019 and 2020, a metastable helium outflow was detected in the atmosphere of GJ 3470 b, indicating the atmosphere is currently escaping at rate 30,000-100,000 tons per second, or 0.16-0.53 Earth masses per billion years.<ref name="Palle2020"/><ref name="Ninan2020"/>

== Gallery ==
<gallery>
File:Structure of Exoplanet GJ 3470 b.tif|Structure of Exoplanet GJ 3470 b.<ref>{{cite web |title=Structure of Exoplanet GJ 3470 b |url=https://www.spacetelescope.org/images/opo1938a/ |website=www.spacetelescope.org |accessdate=5 July 2019 |language=en}}</ref>
File:Artist's impression of gas streaming from GJ 3470b.tif|Artist's impression of gas streaming from GJ 3470b.<ref>{{cite web |title=Artist's impression of gas streaming from GJ 3470b |url=https://spacetelescope.org/images/opo1852a/ |website=www.spacetelescope.org |accessdate=17 December 2018 |language=en}}</ref>
</gallery>{{Planetary radius|base=Earth|Exoplanet=GJ 3470b|radius=419}}{{Clear}}

== See also ==
*[[Astronomy:KELT-9b|KELT-9b]]
*[[Astronomy:GJ 3470|GJ 3470]]
*[[Astronomy:Kepler-51|Kepler-51]]

== References ==
{{Reflist|2|refs=

<ref name="Bonfils2012">{{Cite journal |doi=10.1051/0004-6361/201219623 |arxiv=1206.5307 |title=A hot Uranus transiting the nearby M dwarf GJ3470. Detected with HARPS velocimetry. Captured in transit with TRAPPIST photometry |journal=Astronomy & Astrophysics |volume=546 |pages=A27 |last1=Bonfils |first1=Xavier |last2=Gillon |first2=Michaël |last3=Udry |first3=Stéphane |last4=Armstrong |first4=David |last5=Bouchy |first5=François |last6=Delfosse |first6=Xavier |last7=Forveille |first7=Thierry |last8=Fumel |first8=Aurélie |last9=Jehin |first9=Emmanuël |last10=Lendl |first10=Monika |last11=Lovis |first11=Christophe |last12=Mayor |first12=Michel |last13=McCormac |first13=James |last14=Neves |first14=Vasco <!-- de Matos Ferreira Mendes --> |last15=Pepe |first15=Francesco |last16=Perrier |first16=Christian |last17=Pollacco<!-- sometimes misspelled as Pollaco --> |first17=Don L. |last18=Queloz |first18=Didier |last19=Santos |first19=Nuno C. |year=2012 |bibcode=2012A&A...546A..27B |s2cid=12963626}}</ref>

<ref name="Fukui2013">{{Cite journal |arxiv=1302.7257 |last1=Fukui |first1=Akihiko |title=Optical-to-Near-Infrared Simultaneous Observations for the Hot Uranus GJ3470b: A Hint for Cloud-free Atmosphere |journal=The Astrophysical Journal |volume=770 |issue=2 |pages=95 |last2=Narita |first2=Norio |last3=Kurosaki |first3=Kenji |last4=Ikoma |first4=Masahiro |last5=Yanagisawa |first5=Kenshi |last6=Kuroda |first6=Daisuke |last7=Shimizu |first7=Yasuhiro |last8= Takahashi |first8=Yasuhiro H. |last9=Ohnuki |first9=Hiroshi |last10=Onitsuka |first10=Masahiro |last11=Hirano |first11=Teruyuki |last12=Suenaga |first12=Takuya |last13=Kawauchi |first13=Kiyoe |last14=Nagayama |first14=Shogo |last15=Ohta |first15=Kouji |last16=Yoshida |first16=Michitoshi |last17=Kawai |first17=Nobuyuki |last18=Izumiura |first18=Hideyuki |display-authors=1 |year=2013 |doi=10.1088/0004-637X/770/2/95 |bibcode = 2013ApJ...770...95F |s2cid=119118506 }}</ref>

<ref name="Kokori2023">{{cite journal | title=ExoClock Project. III. 450 New Exoplanet Ephemerides from Ground and Space Observations | last1=Kokori | first1=A. | last2=Tsiaras | first2=A. | last3=Edwards | first3=B. | last4=Jones | first4=A. | last5=Pantelidou | first5=G. | last6=Tinetti | first6=G. | last7=Bewersdorff | first7=L. | last8=Iliadou | first8=A. | last9=Jongen | first9=Y. | last10=Lekkas | first10=G. | last11=Nastasi | first11=A. | last12=Poultourtzidis | first12=E. | last13=Sidiropoulos | first13=C. | last14=Walter | first14=F. | last15=Wünsche | first15=A. | last16=Abraham | first16=R. | last17=Agnihotri | first17=V. K. | last18=Albanesi | first18=R. | last19=Arce-Mansego | first19=E. | last20=Arnot | first20=D. | last21=Audejean | first21=M. | last22=Aumasson | first22=C. | last23=Bachschmidt | first23=M. | last24=Baj | first24=G. | last25=Barroy | first25=P. R. | last26=Belinski | first26=A. A. | last27=Bennett | first27=D. | last28=Benni | first28=P. | last29=Bernacki | first29=K. | last30=Betti | first30=L. | display-authors=1 | journal=The Astrophysical Journal Supplement Series | date=14 February 2023 | volume=265 | issue=1 | page=<!-- to prevent citation bot adding nonexistent page number--> | article-number=4 | bibcode=2023ApJS..265....4K | bibcode-access=free | doi=10.3847/1538-4365/ac9da4 | arxiv=2209.09673 | doi-access=free }} [https://vizier.cds.unistra.fr/viz-bin/VizieR-5?-out.add=.&-source=J/ApJS/265/4/table7&recno=11 Vizier catalog entry ]</ref>

<ref name="Nascimbeni2013">{{cite journal  |last1=Nascimbeni |first1=Valerio |title=The blue sky of GJ3470b: the atmosphere of a low-mass planet unveiled by ground-based photometry |last2=Piotto |first2=Giampaolo |last3= Pagano |first3=Isabella |last4= Scandariato |first4=Gaetano |last5=Sani |first5=Eleonora |last6=Fumana |first6=M. | journal=Astronomy and Astrophysics  |volume=559    |pages=A32  |year=2013 |doi=10.1051/0004-6361/201321971 |bibcode=2013A&A...559A..32N |arxiv = 1308.6765 |s2cid=118497221 }}</ref>

<ref name="Dragomir2015">{{cite journal  |last1=Dragomir |first1=Diana |title=Rayleigh Scattering in the Atmosphere of the Warm Exo-Neptune GJ 3470b |last2=Benneke |first2=Björn |last3= Pearson |first3=Kyle A. |last4= Crossfield |first4=Ian J. M. |last5=Eastman |first5=Jason |last6=Barman |first6=Travis |last7= Biddle |first7=Lauren I. |display-authors=1 | journal=The Astrophysical Journal  |volume=814  |issue=2  |pages=9  |year=2015 |doi=10.1088/0004-637X/814/2/102 |bibcode=2015ApJ...814..102D |arxiv = 1511.05601 |s2cid=26425223 }}</ref>

<ref name="Chen2017">{{cite journal |arxiv=1703.01817 |doi=10.1051/0004-6361/201630228 |title=The GTC exoplanet transit spectroscopy survey |year=2017 |last1=Chen |first1=G. |last2=Guenther |first2=E. W. |last3=Pallé |first3=E. |last4=Nortmann |first4=L. |last5=Nowak |first5=G. |last6=Kunz |first6=S. |last7=Parviainen |first7=H. |last8=Murgas |first8=F. |journal=Astronomy & Astrophysics |volume=600 |pages=A138 |s2cid=119269112 |bibcode=2017A&A...600A.138C}}</ref>

<ref name="Bourrier2018">{{cite journal|arxiv=1812.05119|doi=10.1051/0004-6361/201833675|title=Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470b|year=2018|last1=Bourrier|first1=V.|last2=Lecavelier Des Etangs|first2=A.|last3=Ehrenreich|first3=D.|last4=Sanz-Forcada|first4=J.|last5=Allart|first5=R.|last6=Ballester|first6=G. E.|last7=Buchhave|first7=L. A.|last8=Cohen|first8=O.|last9=Deming|first9=D.|last10=Evans|first10=T. M.|last11=García Muñoz|first11=A.|last12=Henry|first12=G. W.|last13=Kataria|first13=T.|last14=Lavvas|first14=P.|last15=Lewis|first15=N.|last16=López-Morales|first16=M.|last17=Marley|first17=M.|last18=Sing|first18=D. K.|last19=Wakeford|first19=H. R.|journal=Astronomy & Astrophysics|volume=620|pages=A147|bibcode=2018A&A...620A.147B|s2cid=239583863 }}</ref>

<ref name="Benneke2019">{{cite journal|arxiv=1907.00449|doi=10.1038/s41550-019-0800-5|title=A sub-Neptune exoplanet with a low-metallicity methane-depleted atmosphere and Mie-scattering clouds|year=2019|last1=Benneke|first1=Björn|last2=Knutson|first2=Heather A.|last3=Lothringer|first3=Joshua|last4=Crossfield|first4=Ian J.M.|last5=Moses|first5=Julianne I.|last6=Morley|first6=Caroline|last7=Kreidberg|first7=Laura|last8=Fulton|first8=Benjamin J.|last9=Dragomir|first9=Diana|last10=Howard|first10=Andrew W.|last11=Wong|first11=Ian|last12=Désert|first12=Jean-Michel|last13=McCullough|first13=Peter R.|last14=Kempton|first14=Eliza M.-R.|last15=Fortney|first15=Jonathan|last16=Gilliland|first16=Ronald|last17=Deming|first17=Drake|last18=Kammer|first18=Joshua|journal=Nature Astronomy|volume=3|issue=9|pages=813–821|bibcode=2019NatAs...3..813B|s2cid=256707037 }}</ref>

<ref name="Ninan2020">{{cite journal|arxiv=1910.02070|last1=Ninan|first1=Joe P.|last2=Stefansson|first2=Gudmundur|last3=Mahadevan|first3=Suvrath|last4=Bender|first4=Chad|last5=Robertson|first5=Paul|last6=Ramsey|first6=Lawrence|last7=Terrien|first7=Ryan|last8=Wright|first8=Jason|last9=Diddams|first9=Scott A.|last10=Kanodia|first10=Shubham|last11=Cochran|first11=William|last12=Endl|first12=Michael|last13=Ford|first13=Eric B.|last14=Fredrick|first14=Connor|last15=Halverson|first15=Samuel|last16=Hearty|first16=Fred|last17=Jennings|first17=Jeff|last18=Kaplan|first18=Kyle|last19=Lubar|first19=Emily|last20=Metcalf|first20=Andrew J.|last21=Monson|first21=Andrew|last22=Nitroy|first22=Colin|last23=Roy|first23=Arpita|last24=Schwab|first24=Christian|title=Evidence for He i 10830 Å Absorption during the Transit of a Warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder|journal=The Astrophysical Journal |year=2019|volume=894 |issue=2 |page=97 |doi=10.3847/1538-4357/ab8559 |s2cid=203737369 |bibcode=2020ApJ...894...97N |doi-access=free }}</ref>

<ref name="Palle2020">{{cite journal |arxiv=2004.12812 |last1=Pallé |first1=E. |last2=Nortmann |first2=L. |last3=Casasayas-Barris |first3=N. |last4=Lampón |first4=M. |last5=López-Puertas |first5=M. |last6=Caballero |first6=J. A. |last7=Sanz-Forcada |first7=J. |last8=Lara |first8=L. M. |last9=Nagel |first9=E. |last10=Yan |first10=F. |last11=Alonso-Floriano |first11=F. J. |last12=Amado |first12=P. J. |last13=Chen |first13=G. |last14=Cifuentes |first14=C. |last15=Cortés-Contreras |first15=M. |last16=Czesla |first16=S. |last17=Molaverdikhani |first17=K. |last18=Montes |first18=D. |last19=Passegger |first19=V. M. |last20=Quirrenbach |first20=A. |last21=Reiners |first21=Ansgar |last22=Ribas |first22=I. |last23=Sánchez-López |first23=A. |last24=Schweitzer |first24=A. |last25=Stangret |first25=M. |last26=Zapatero-Osorio |first26=María Rosa |last27=Zechmeister |first27=M. |title=A He I upper atmosphere around the warm Neptune GJ 3470 B |journal=Astronomy & Astrophysics |year=2020 |volume=638 |pages=A61 |doi=10.1051/0004-6361/202037719 |s2cid=216553362 |bibcode=2020A&A...638A..61P}}</ref>

<ref name="Stefansson2022">{{cite journal|arxiv=2111.01295|year=2022|title=The Warm Neptune GJ 3470b Has a Polar Orbit|doi=10.3847/2041-8213/ac6e3c |last1=Stefànsson |first1=Guđmundur |last2=Mahadevan |first2=Suvrath |last3=Petrovich |first3=Cristobal |last4=Winn |first4=Joshua N. |last5=Kanodia |first5=Shubham |last6=Millholland |first6=Sarah C. |last7=Maney |first7=Marissa |last8=Cañas |first8=Caleb I. |last9=Wisniewski |first9=John |last10=Robertson |first10=Paul |last11=Ninan |first11=Joe P. |last12=Ford |first12=Eric B. |last13=Bender |first13=Chad F. |last14=Blake |first14=Cullen H. |last15=Cegla |first15=Heather |last16=Cochran |first16=William D. |last17=Diddams |first17=Scott A. |last18=Dong |first18=Jiayin |last19=Endl |first19=Michael |last20=Fredrick |first20=Connor |last21=Halverson |first21=Samuel |last22=Hearty |first22=Fred |last23=Hebb |first23=Leslie |last24=Hirano |first24=Teruyuki |last25=Lin |first25=Andrea S. J. |last26=Logsdon |first26=Sarah E. |last27=Lubar |first27=Emily |last28=McElwain |first28=Michael W. |last29=Metcalf |first29=Andrew J. |last30=Monson |first30=Andrew |journal=The Astrophysical Journal Letters |volume=931 |issue=2 |pages=L15 |bibcode=2022ApJ...931L..15S |s2cid=240419664 |display-authors=1 |doi-access=free }}</ref>

<ref name="NEW2022">{{cite web |url=https://www.nameexoworlds.iau.org/2022approved-names |title=2022 Approved Names |website=nameexoworlds.iau.org |publisher=[[Organization:International Astronomical Union|IAU]] |access-date=7 June 2023}}</ref>

<ref name="Awiphan2016">{{cite journal |last1=Awiphan |first1=S. |last2=Kerins |first2=E. |display-authors=0 |date=December 2016 |title=Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b |journal=[[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society]] |volume=463 |issue=3 |pages=2574–2582 |doi=10.1093/mnras/stw2148 |arxiv=1606.02962 |bibcode=2016MNRAS.463.2574A}}</ref>

<ref name="Kosiarek2019">{{cite journal |last1=Kosiarek |first1=Molly R. |last2=Crossfield |first2=Ian J. M. |display-authors=0 |date=March 2019 |title=Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits |journal=[[Astronomy:The Astronomical Journal|The Astronomical Journal]] |volume=157 |issue=3 |pages=97 |doi=10.3847/1538-3881/aaf79c |arxiv=1812.08241 |bibcode=2019AJ....157...97K |s2cid=119440420 |doi-access=free }}</ref>

}}

{{2012 in space}}

[[Category:Exoplanets detected by radial velocity]]
[[Category:Transiting exoplanets]]
[[Category:Cancer (constellation)]]

{{Sourceattribution|GJ 3470 b}}