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{{Short description|Accumulationofmatter around a planet}} |
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[[File: |
[[File:PDS 70 closeup - eso2111a.jpg|thumb|315x315px|Circumplanetary disk around [[exoplanet]] [[PDS 70c]] (point-like source on the right side)]] |
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A '''circumplanetary disk''' (or '''circumplanetary disc''') is a [[torus]], pancake or ring-shaped accumulation of [[matter]] composed of [[gas]], [[Cosmic dust|dust]], [[planetesimal]]s, [[asteroid]]s or collision fragments in [[orbit]] around a [[planet]]. |
A '''circumplanetary disk''' (or '''circumplanetary disc, short CPD''') is a [[torus]], pancake or ring-shaped accumulation of [[matter]] composed of [[gas]], [[Cosmic dust|dust]], [[planetesimal]]s, [[asteroid]]s or collision fragments in [[orbit]] around a [[planet]]. They are reservoirs of material out of which [[Natural satellite|moon]]s (or [[exomoon]]s or [[subsatellite]]s) may form.<ref name="AST-20211108">{{cite news |last=Parks |first=Jake |title=Snapshot: ALMA spots moon-forming disk around distant exoplanet - This stellar shot serves as the first unambiguous detection of a circumplanetary disk capable of brewing its own moon. |url=https://astronomy.com/magazine/news/2021/11/snapshot-alma-spots-moon-forming-disk-around-distant-exoplanet |date=8 November 2021 |work=[[Astronomy (magazine)|Astronomy]] |accessdate=9 November 2021 }}</ref> Such a disk can manifest itself in various ways. |
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In August 2018 astronomers reported the probable detection of a circumplanetary disk around [[CS Chamaeleontis B|CS Cha B]].<ref>{{cite journal |last1=Ginski |first1=Christian |title=First direct detection of a polarized companion outside a resolved circumbinary disk around CS Chamaeleonis |journal=[[Astronomy & Astrophysics]] |date=August 2018 |volume=616 |issue=79 |page=18 |doi=10.1051/0004-6361/201732417|doi-access=free }}</ref> The authors state that "The CS Cha system is the only system in which a circumplanetary disc is likely present as well as a resolved circumstellar disc."<ref>{{cite news |last1=Starr |first1=Michelle |title=Astronomers Have Accidentally Taken a Direct Photo of a Possible Baby Exoplanet |url=https://www.sciencealert.com/astronomers-have-accidentally-taken-a-direct-photograph-of-a-possible-baby-exoplanet |access-date=10 October 2019}}</ref> In 2020 though, the parameters of [[CS Chamaeleontis B|CS Cha B]] were revised, making it an accreting red dwarf star, and making the disk [[circumstellar disk|circumstellar]].<ref>{{citation|arxiv=2007.07831|title=CS Cha B: A disc-obscured M-type star mimicking a polarised planetary companion|year=2020}}</ref> |
In August 2018, astronomers reported the probable detection of a circumplanetary disk around [[CS Chamaeleontis B|CS Cha B]].<ref>{{cite journal |last1=Ginski |first1=Christian |title=First direct detection of a polarized companion outside a resolved circumbinary disk around CS Chamaeleonis |journal=[[Astronomy & Astrophysics]] |date=August 2018 |volume=616 |issue=79 |page=18 |doi=10.1051/0004-6361/201732417|arxiv=1805.02261 |bibcode=2018A&A...616A..79G |doi-access=free }}</ref> The authors state that "The CS Cha system is the only system in which a circumplanetary disc is likely present as well as a resolved circumstellar disc."<ref>{{cite news |last1=Starr |first1=Michelle |title=Astronomers Have Accidentally Taken a Direct Photo of a Possible Baby Exoplanet |url=https://www.sciencealert.com/astronomers-have-accidentally-taken-a-direct-photograph-of-a-possible-baby-exoplanet |access-date=10 October 2019}}</ref> In 2020 though, the parameters of [[CS Chamaeleontis B|CS Cha B]] were revised, making it an accreting red dwarf star, and making the disk [[circumstellar disk|circumstellar]].<ref>{{citation|arxiv=2007.07831|title=CS Cha B: A disc-obscured M-type star mimicking a polarised planetary companion|year=2020|doi=10.1051/0004-6361/202038706 |last1=Haffert |first1=S. Y. |last2=Van Holstein |first2=R. G. |last3=Ginski |first3=C. |last4=Brinchmann |first4=J. |last5=Snellen |first5=I. A. G. |last6=Milli |first6=J. |last7=Stolker |first7=T. |last8=Keller |first8=C. U. |last9=Girard |first9=J. |journal=Astronomy & Astrophysics |volume=640 |pages=L12 |bibcode=2020A&A...640L..12H |s2cid=220525346 }}</ref> |
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== Candidates around other exoplanets == |
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In |
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Possible circumplanetary disks have also been detected around exoplanets, [[HD 100546 b]],<ref>{{cite journal |last1=Quanz |first1=Sascha P. |display-authors=etal |title=Confirmation and Characterization of the Protoplanet HD 100546 b—Direct Evidence for Gas Giant Planet Formation at 50 AU |journal=[[The Astrophysical Journal]] |date=July 2015 |volume=807 |issue=1 |page=64 |doi=10.1088/0004-637X/807/1/64 |arxiv=1412.5173 |bibcode=2015ApJ...807...64Q|s2cid=119119314 }}</ref> [[AS 209 b]]<ref>{{cite journal |last1=Bae |first1=Jaehan |display-authors=etal |title=Molecules with ALMA at Planet-forming Scales (MAPS): A Circumplanetary Disk Candidate in Molecular-line Emission in the AS 209 Disk |journal=[[The Astrophysical Journal Letters]] |date=August 2022 |volume=934 |issue=2 |page=20 |doi=10.3847/2041-8213/ac7fa3 |arxiv=2207.05923 |bibcode=2022ApJ...934L..20B |s2cid=250492936 |doi-access=free }}</ref> and [[HD 169142|HD 169142 b]]<ref>{{Cite journal |last1=Hammond |first1=Iain |last2=Christiaens |first2=Valentin |last3=Price |first3=Daniel J. |last4=Toci |first4=Claudia |last5=Pinte |first5=Christophe |last6=Juillard |first6=Sandrine |last7=Garg |first7=Himanshi |date=2023-02-23 |title=Confirmation and Keplerian motion of the gap-carving protoplanet HD 169142 B |journal=Monthly Notices of the Royal Astronomical Society: Letters |volume=522 |pages=L51–L55 |doi=10.1093/mnrasl/slad027 |doi-access=free |arxiv=2302.11302 }}</ref> or planetary-mass companions (PMC; 10-20 {{Jupiter mass}}, separation ≥100 AU), such as [[GSC 06214-00210 b]]<ref>{{cite journal |last1=Bowler |first1=Brendan P. |display-authors=etal |date=June 2015 |title=An ALMA Constraint on the GSC 6214-210 B Circum-Substellar Accretion Disk Mass |journal=[[The Astrophysical Journal]] |volume=805 |issue=2 |page=L17 |arxiv=1505.01483 |bibcode=2015ApJ...805L..17B |doi=10.1088/2041-8205/805/2/L17 |s2cid=29008641}}</ref> and [[DH Tauri b]].<ref>{{cite journal |last1=Wolff |first1=Schuyler G. |display-authors=etal |date=July 2017 |title=An Upper Limit on the Mass of the Circumplanetary Disk for DH Tau b |journal=[[The Astronomical Journal]] |volume=154 |issue=1 |page=26 |arxiv=1705.08470 |bibcode=2017AJ....154...26W |doi=10.3847/1538-3881/aa74cd |s2cid=119339454 |doi-access=free}}</ref> |
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A disk was detected in sub-mm with ALMA around [[SR 12 C|SR 12 c]], a planetary-mass companion. SR 12 c might not have formed from the circumstellar disk material of the host star SR 12, so it might not be considered a true circumplanetary disk. PMC disks are relative common around young objects and are easier to study when compared to circumplanetary disks.<ref>{{Cite journal |last1=Wu |first1=Ya-Lin |last2=Bowler |first2=Brendan P. |last3=Sheehan |first3=Patrick D. |last4=Close |first4=Laird M. |last5=Eisner |first5=Joshua A. |last6=Best |first6=William M. J. |last7=Ward-Duong |first7=Kimberly |last8=Zhu |first8=Zhaohuan |last9=Kraus |first9=Adam L. |date=2022-05-01 |title=ALMA Discovery of a Disk around the Planetary-mass Companion SR 12 c |journal=The Astrophysical Journal |volume=930 |issue=1 |pages=L3 |doi=10.3847/2041-8213/ac6420 |doi-access=free |arxiv=2204.06013 |bibcode=2022ApJ...930L...3W |issn=0004-637X}}</ref> |
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The |
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Several disks were detected around nearby [[Rogue planet|isolated planetary-mass objects]]. Disks around such objects within 300 parsecs were found in [[Rho Ophiuchi cloud complex|Rho Ophiuchi Complex]],<ref name=":23">{{Cite journal |last1=Rilinger |first1=Anneliese M. |last2=Espaillat |first2=Catherine C. |date=2021-11-01 |title=Disk Masses and Dust Evolution of Protoplanetary Disks around Brown Dwarfs |journal=The Astrophysical Journal |volume=921 |issue=2 |pages=182 |arxiv=2106.05247 |bibcode=2021ApJ...921..182R |doi=10.3847/1538-4357/ac09e5 |issn=0004-637X |doi-access=free}}</ref> [[Taurus molecular cloud|Taurus Complex]] (e.g. [[KPNO-Tau 12]]),<ref name=":23" /><ref>{{Cite journal |last1=Best |first1=William M. J. |last2=Liu |first2=Michael C. |last3=Magnier |first3=Eugene A. |last4=Bowler |first4=Brendan P. |last5=Aller |first5=Kimberly M. |last6=Zhang |first6=Zhoujian |last7=Kotson |first7=Michael C. |last8=Burgett |first8=W. S. |last9=Chambers |first9=K. C. |last10=Draper |first10=P. W. |last11=Flewelling |first11=H. |last12=Hodapp |first12=K. W. |last13=Kaiser |first13=N. |last14=Metcalfe |first14=N. |last15=Wainscoat |first15=R. J. |date=2017-03-01 |title=A Search for L/T Transition Dwarfs with Pan-STARRS1 and WISE. III. Young L Dwarf Discoveries and Proper Motion Catalogs in Taurus and Scorpius-Centaurus |journal=The Astrophysical Journal |volume=837 |issue=1 |pages=95 |arxiv=1702.00789 |bibcode=2017ApJ...837...95B |doi=10.3847/1538-4357/aa5df0 |issn=0004-637X |doi-access=free |hdl-access=free |hdl=1721.1/109753}}</ref> Lupus I Cloud<ref name=":22">{{Cite journal |last1=Jayawardhana |first1=Ray |last2=Ivanov |first2=Valentin D. |date=2006-08-01 |title=Spectroscopy of Young Planetary Mass Candidates with Disks |journal=The Astrophysical Journal |volume=647 |issue=2 |pages=L167–L170 |arxiv=astro-ph/0607152 |bibcode=2006ApJ...647L.167J |doi=10.1086/507522 |issn=0004-637X |doi-access=free}}</ref> and the [[Chamaeleon complex|Chamaeleon Complex]] (e.g. the well studied [[OTS 44]] and [[Cha 110913−773444]]<ref>{{cite journal |last1=Luhman |first1=K. L. |display-authors=etal |title=Discovery of a Planetary-Mass Brown Dwarf with a Circumstellar Disk |journal=[[The Astrophysical Journal]] |date=December 2005 |volume=635 |issue=1 |pages=L93–L96 |doi=10.1086/498868 |arxiv=astro-ph/0511807 |bibcode=2005ApJ...635L..93L|s2cid=11685964 }}</ref>). These objects with disks are free-floating and are most of the time called circumstellar disks, despite likely being similar to circumplanetary disks. |
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According to [[Andrea Isella]], lead researcher from the [[Rice University]] in [[Houston, Texas]], "For the first time, we can conclusively see the tell-tale signs of a circumplanetary disk, which helps to support many of the current theories of [[planet formation]] ... By comparing our observations to the [[Infrared astronomy|high-resolution infrared]] and [[Visible-light astronomy|optical]] images, we can clearly see that an otherwise enigmatic concentration of [[Interplanetary dust cloud|tiny dust particles]] is actually a planet-girding disk of dust, the first such feature ever conclusively observed."<ref name="CM-20190713" /> |
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[[2M1207b]] was suspected to haveacircumplanetary disk in the past.<ref>{{cite journal |last1=Mohanty |first1=Subhanjoy |display-authors=etal |date=March 2007 |title=The Planetary Mass Companion 2MASS 1207-3932B: Temperature, Mass, and Evidence for an Edge-on Disk |journal=[[The Astrophysical Journal]] |volume=657 |issue=2 |pages=1064–1091 |arxiv=astro-ph/0610550 |bibcode=2007ApJ...657.1064M |doi=10.1086/510877 |s2cid=17326111}}</ref> New observations from [[James Webb Space Telescope|JWST]]/[[NIRSpec]] were able to confirm accretion fromanunseen disk by detecting emission from hydrogen and helium. The classification of a circumplanetary disk is however being disputed because 2M1207b (or 2M1207B) might be classified as a binary together with 2M1207A and not an exoplanet. This would make the disk around 2M1207b a [[Circumstellar disc|circumstellar disk]], despite not being around a star, but around a 5-6 {{Jupiter mass|link=true|jup=true}} [[planetary-mass object]].<ref>{{Cite journal |last1=Luhman |first1=K. L. |last2=Tremblin |first2=P. |last3=Birkmann |first3=S. M. |last4=Manjavacas |first4=E. |last5=Valenti |first5=J. |last6=Alves de Oliveira |first6=C. |last7=Beck |first7=T. L. |last8=Giardino |first8=G. |last9=Lützgendorf |first9=N. |last10=Rauscher |first10=B. J. |last11=Sirianni |first11=M. |date=2023-06-01 |title=JWST/NIRSpec Observations of the Planetary Mass Companion TWA 27B |journal=The Astrophysical Journal |volume=949 |issue=2 |pages=L36 |doi=10.3847/2041-8213/acd635 |bibcode=2023ApJ...949L..36L |issn=0004-637X|doi-access=free |arxiv=2305.18603 }}</ref> |
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=== PDS 70 === |
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{{Main|PDS 70}} |
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⚫ | The disk around the planet c of the PDS 70 system is the best evidence for a circumplanetary disk at the time of its discovery. The exoplanet is part of the multiplanetary PDS 70 star system, about {{convert|370|ly|pc|abbr=off}} from Earth.<ref name="GZM-20190712">{{cite news |last=Mandelbaum |first=Ryan F. |title=Astronomers Think They've Spotted a Moon Forming Around an Exoplanet |url=https://gizmodo.com/astronomers-think-they-ve-spotted-a-moon-forming-around-1836323615 |date=12 July 2019 |work=[[Gizmodo]] |access-date=12 July 2019 }}</ref> |
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==== PDS 70b ==== |
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In June 2019 astronomers reported the detection of evidence of a circumplanetary disk around [[PDS 70b]]<ref>{{cite journal |last1=Christiaens |first1=Valentin |title=Evidence for a circumplanetary disk around protoplanet PDS 70 b |journal=[[The Astrophysical Journal Letters]] |date=June 2019 |volume=877 |issue=2 |pages=L33 |doi=10.3847/2041-8213/ab212b|arxiv=1905.06370 |bibcode=2019ApJ...877L..33C |s2cid=155100321 |doi-access=free }}</ref> using spectroscopy and accretion signatures. Both types of these signatures had previously been detected for other planetary candidates. A later infrared characterization could not confirm the spectroscopic evidence for the disk around PDS 70b and reports weak evidence that the current data favors a model with a single blackbody component.<ref>{{Cite journal |last1=Stolker |first1=T. |last2=Marleau |first2=G.-D. |last3=Cugno |first3=G. |last4=Mollière |first4=P. |last5=Quanz |first5=S. P. |last6=Todorov |first6=K. O. |last7=Kühn |first7=J. |date=December 2020 |title=MIRACLES: atmospheric characterization of directly imaged planets and substellar companions at 4–5 μ m: II. Constraints on the mass and radius of the enshrouded planet PDS 70 b |journal=Astronomy & Astrophysics |volume=644 |pages=A13 |doi=10.1051/0004-6361/202038878 |arxiv=2009.04483 |bibcode=2020A&A...644A..13S |issn=0004-6361|doi-access=free }}</ref> |
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==== PDS 70c ==== |
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⚫ | InJuly 2019 astronomers reported the first-ever detection using the [[Atacama Large Millimeter/submillimeter Array]] (ALMA)<ref name="TAJL-20190711">{{cite journal |author=Isella, Andrea |display-authors=et al. |date=11 July 2019 |title=Detection of Continuum Submillimeter Emission Associated with Candidate Protoplanets |journal=[[The Astrophysical Journal Letters]] |volume=879 |pages=L25 |arxiv=1906.06308 |bibcode=2019ApJ...879L..25I |doi=10.3847/2041-8213/ab2a12 |s2cid=189897829 |doi-access=free |number=2}}</ref><ref name="NRAO-20190711">{{cite news |last=Blue |first=Charles E. |date=11 July 2019 |title='Moon-forming' Circumplanetary Disk Discovered in Distant Star System |url=https://public.nrao.edu/news/2019-alma-circumplanetary/ |access-date=11 July 2019 |work=[[National Radio Astronomy Observatory]]}}</ref><ref name="CM-20190713">{{cite news |last=Carne |first=Nick |date=13 July 2019 |title='Moon-forming' disk found in distant star system - Discovery helps confirm theories of planet formation, astronomers say. |url=https://cosmosmagazine.com/space/moon-forming-disk-found-in-distant-start-system |url-status=dead |archive-url=https://web.archive.org/web/20190712155910/https://cosmosmagazine.com/space/moon-forming-disk-found-in-distant-start-system |archive-date=12 July 2019 |access-date=12 July 2019 |work=[[Cosmos (Australian magazine)|Cosmos]]}}</ref> of a circumplanetary disk.<ref name="TAJL-20190711" /><ref name="NRAO-20190711" /><ref name="PHY-20190711">{{cite news |last=Boyd |first=Jade |date=11 July 2019 |title=Moon-forming disk discovered around distant planet |url=https://phys.org/news/2019-07-moon-forming-disk-distant-planet.html |access-date=11 July 2019 |work=[[Phys.org]]}}</ref> ALMA studies, using [[Extremely high frequency|millimetre]] and [[Submillimetre astronomy|submillimetre]] wavelengths, are better at observing [[Interplanetary dust cloud|dust]] concentrated in interplanetary regions, since stars emit comparatively little light at these wavelengths, and since [[Visible-light astronomy|optical observations]] are often obscured by overwhelming glare from the bright host star. The circumplanetary disk was detected around a young massive, [[Jupiter]]-like [[exoplanet]], [[PDS 70c]].<ref name="TAJL-20190711" /><ref name="NRAO-20190711" /><ref name="PHY-20190711" /> |
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According to [[Andrea Isella]], lead researcher from the [[Rice University]] in [[Houston, Texas]], "For the first time, we can conclusively see the tell-tale signs of a circumplanetary disk, which helps to support many of the current theories of [[planet formation]] ... By comparing our observations to the [[Infrared astronomy|high-resolution infrared]] and [[Visible-light astronomy|optical]] images, we can clearly see that an otherwise enigmatic concentration of [[Interplanetary dust cloud|tiny dust particles]] is actually a planet-girding disk of dust, the first such feature ever conclusively observed."<ref name="CM-20190713" /> Jason Wang from Caltech, lead researcher of another publication, describes, "if a planet appears to sit on top of the disk, which is the case with PDS 70c"<ref>{{Cite web |last=Observatory |first=W. M. Keck |title=Astronomers confirm existence of two giant newborn planets in PDS 70 system |url=https://phys.org/news/2020-05-astronomers-giant-newborn-planets-pds.html |access-date=2022-07-27 |website=phys.org |language=en}}</ref> then the signal around [[PDS 70|PDS 70c]] needs to be spatially separated from the outer ring, not the case in 2019. However, in July 2021 higher resolution, conclusively resolved data were presented.<ref name=":0">{{Cite journal |last1=Benisty |first1=Myriam |last2=Bae |first2=Jaehan |last3=Facchini |first3=Stefano |last4=Keppler |first4=Miriam |last5=Teague |first5=Richard |last6=Isella |first6=Andrea |last7=Kurtovic |first7=Nicolas T. |last8=Pérez |first8=Laura M. |last9=Sierra |first9=Anibal |last10=Andrews |first10=Sean M. |last11=Carpenter |first11=John |date=2021-07-01 |title=A Circumplanetary Disk around PDS70c |journal=The Astrophysical Journal Letters |volume=916 |issue=1 |pages=L2 |doi=10.3847/2041-8213/ac0f83 |arxiv=2108.07123 |bibcode=2021ApJ...916L...2B |s2cid=236186222 |issn=2041-8205 |doi-access=free }}</ref> |
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The planet PDS 70c is detected in [[Hydrogen-alpha|H-alpha]], which is seen as evidence that it accretes material from the circumplanetary disk at a rate of 10<sup>{{Val|-8|0.4}}</sup> {{Jupiter mass|link=true}} per year.<ref>{{Cite journal |last1=Haffert |first1=S. Y. |last2=Bohn |first2=A. J. |last3=de Boer |first3=J. |last4=Snellen |first4=I. A. G. |last5=Brinchmann |first5=J. |last6=Girard |first6=J. H. |last7=Keller |first7=C. U. |last8=Bacon |first8=R. |date=2019-06-01 |title=Two accreting protoplanets around the young star PDS 70 |url=https://ui.adsabs.harvard.edu/abs/2019NatAs...3..749H |journal=Nature Astronomy |volume=3 |issue=8 |pages=749–754 |doi=10.1038/s41550-019-0780-5 |issn=2397-3366|arxiv=1906.01486 |bibcode=2019NatAs...3..749H }}</ref> From ALMA observations it was shown that this disk has a radius smaller than 1.2 [[Astronomical unit|astronomical units]] (AU) or a third of the [[Hill sphere|Hill radius]]. The dust mass was estimated around 0.007 or 0.031 {{Earth mass|link=true}} (0.57 to 2.5 [[Moon]] masses), depending on the grain size used for the modelling.<ref name=":0" /> Later modelling showed that the disk around PDS 70c is optically thick and has an estimated dust mass of 0.07 to 0.7 {{Earth mass}} (5.7 to 57 Moon masses). The total (dust+gas) mass of the disk should be higher. The planet's luminosity is the dominant heating mechanism within 0.6 AU of the CPD. Beyond that the [[Photon|photons]] from the star heat the disk.<ref>{{Cite journal |last1=Portilla-Revelo |first1=B. |last2=Kamp |first2=I. |last3=Rab |first3=Ch. |last4=van Dishoeck |first4=E. F. |last5=Keppler |first5=M. |last6=Min |first6=M. |last7=Muro-Arena |first7=G. A. |date=2022-02-01 |title=Self-consistent modelling of the dust component in protoplanetary and circumplanetary disks: the case of PDS 70 |url=https://ui.adsabs.harvard.edu/abs/2022A&A...658A..89P |journal=Astronomy and Astrophysics |volume=658 |pages=A89 |doi=10.1051/0004-6361/202141764 |issn=0004-6361|arxiv=2111.08648 |bibcode=2022A&A...658A..89P }}</ref> |
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== See also == |
== See also == |
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* {{annotated link|Accretion disc}} |
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* [[Circumplanetary dust]] |
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* {{annotated link|Disrupted planet}} |
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* {{annotated link|Extrasolar planet}} |
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⚫ | * {{annotated link|Formation and evolution of the Solar System}} |
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* [[Extrasolar planet]] |
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* {{annotated link|Ring system}} |
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== External links == |
== External links == |
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*[http://astro.berkeley.edu/~kalas/disksite/pages/gallery.html Image Gallery of Dust disks] ( |
*[http://astro.berkeley.edu/~kalas/disksite/pages/gallery.html Image Gallery of Circumstellar Dust disks] ([[Paul Kalas]]; "[http://astro.berkeley.edu/~kalas/disksite/index.html Learning Site])" |
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* {{YouTube|ZmUCm1O1vuY|Video (1:20) − Moon-forming Circumplanetary disc}} ([[European Southern Observatory|ESO]]; July 2021) |
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{{Exoplanet|state=collapsed}} |
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[[Category:Circumstellar disks| |
[[Category:Circumstellar disks|*]] |
Acircumplanetary disk (orcircumplanetary disc, short CPD) is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a planet. They are reservoirs of material out of which moons (orexomoonsorsubsatellites) may form.[1] Such a disk can manifest itself in various ways.
In August 2018, astronomers reported the probable detection of a circumplanetary disk around CS Cha B.[2] The authors state that "The CS Cha system is the only system in which a circumplanetary disc is likely present as well as a resolved circumstellar disc."[3] In 2020 though, the parameters of CS Cha B were revised, making it an accreting red dwarf star, and making the disk circumstellar.[4]
Possible circumplanetary disks have also been detected around exoplanets, HD 100546 b,[5] AS 209 b[6] and HD 169142 b[7] or planetary-mass companions (PMC; 10-20 MJ, separation ≥100 AU), such as GSC 06214-00210 b[8] and DH Tauri b.[9]
A disk was detected in sub-mm with ALMA around SR 12 c, a planetary-mass companion. SR 12 c might not have formed from the circumstellar disk material of the host star SR 12, so it might not be considered a true circumplanetary disk. PMC disks are relative common around young objects and are easier to study when compared to circumplanetary disks.[10]
Several disks were detected around nearby isolated planetary-mass objects. Disks around such objects within 300 parsecs were found in Rho Ophiuchi Complex,[11] Taurus Complex (e.g. KPNO-Tau 12),[11][12] Lupus I Cloud[13] and the Chamaeleon Complex (e.g. the well studied OTS 44 and Cha 110913−773444[14]). These objects with disks are free-floating and are most of the time called circumstellar disks, despite likely being similar to circumplanetary disks.
2M1207b was suspected to have a circumplanetary disk in the past.[15] New observations from JWST/NIRSpec were able to confirm accretion from an unseen disk by detecting emission from hydrogen and helium. The classification of a circumplanetary disk is however being disputed because 2M1207b (or 2M1207B) might be classified as a binary together with 2M1207A and not an exoplanet. This would make the disk around 2M1207b a circumstellar disk, despite not being around a star, but around a 5-6 MJup planetary-mass object.[16]
The disk around the planet c of the PDS 70 system is the best evidence for a circumplanetary disk at the time of its discovery. The exoplanet is part of the multiplanetary PDS 70 star system, about 370 light-years (110 parsecs) from Earth.[17]
In June 2019 astronomers reported the detection of evidence of a circumplanetary disk around PDS 70b[18] using spectroscopy and accretion signatures. Both types of these signatures had previously been detected for other planetary candidates. A later infrared characterization could not confirm the spectroscopic evidence for the disk around PDS 70b and reports weak evidence that the current data favors a model with a single blackbody component.[19]
In July 2019 astronomers reported the first-ever detection using the Atacama Large Millimeter/submillimeter Array (ALMA)[20][21][22] of a circumplanetary disk.[20][21][23] ALMA studies, using millimetre and submillimetre wavelengths, are better at observing dust concentrated in interplanetary regions, since stars emit comparatively little light at these wavelengths, and since optical observations are often obscured by overwhelming glare from the bright host star. The circumplanetary disk was detected around a young massive, Jupiter-like exoplanet, PDS 70c.[20][21][23]
According to Andrea Isella, lead researcher from the Rice UniversityinHouston, Texas, "For the first time, we can conclusively see the tell-tale signs of a circumplanetary disk, which helps to support many of the current theories of planet formation ... By comparing our observations to the high-resolution infrared and optical images, we can clearly see that an otherwise enigmatic concentration of tiny dust particles is actually a planet-girding disk of dust, the first such feature ever conclusively observed."[22] Jason Wang from Caltech, lead researcher of another publication, describes, "if a planet appears to sit on top of the disk, which is the case with PDS 70c"[24] then the signal around PDS 70c needs to be spatially separated from the outer ring, not the case in 2019. However, in July 2021 higher resolution, conclusively resolved data were presented.[25]
The planet PDS 70c is detected in H-alpha, which is seen as evidence that it accretes material from the circumplanetary disk at a rate of 10−8±0.4 MJ per year.[26] From ALMA observations it was shown that this disk has a radius smaller than 1.2 astronomical units (AU) or a third of the Hill radius. The dust mass was estimated around 0.007 or 0.031 ME (0.57 to 2.5 Moon masses), depending on the grain size used for the modelling.[25] Later modelling showed that the disk around PDS 70c is optically thick and has an estimated dust mass of 0.07 to 0.7 ME (5.7 to 57 Moon masses). The total (dust+gas) mass of the disk should be higher. The planet's luminosity is the dominant heating mechanism within 0.6 AU of the CPD. Beyond that the photons from the star heat the disk.[27]