A circumplanetary disk (or circumplanetary disc) is a

torus In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanar with the circle. If the axis of revolution does n ...

, pancake or ring-shaped accumulation of

matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic part ...

composed of gas,

dust Dust is made of fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian process), volcanic eruptions, and pollution. Dust in ...

planetesimal Planetesimals are solid objects thought to exist in protoplanetary disks and debris disks. Per the Chamberlin–Moulton planetesimal hypothesis, they are believed to form out of cosmic dust grains. Believed to have formed in the Solar System ...

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

s or collision fragments in

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

around a

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

. Around the planets, they are the reservoirs of material out of which

moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

s (or

exomoon An exomoon or extrasolar moon is a natural satellite that orbits an exoplanet or other non-stellar extrasolar body. Exomoons are difficult to detect and confirm using current techniques, and to date there have been no confirmed exomoon detecti ...

s or subsatellites) may form. 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. 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." In 2020 though, the parameters of CS Cha B were revised, making it an accreting red dwarf star, and making the disk circumstellar. In June 2019 astronomers reported the detection of evidence of a circumplanetary disk around PDS 70b using spectroscopy and accretion signatures. Both types of these signatures were also detected for other planetary candidates before. 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. In July 2019 astronomers reported the first-ever detection using the

Atacama Large Millimeter/submillimeter Array The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of 66 radio telescopes in the Atacama Desert of northern Chile, which observe electromagnetic radiation at millimeter and submillimeter wavelengths. The ar ...

(ALMA) of a circumplanetary disk. ALMA studies, using

millimetre 330px, Different lengths as in respect to the electromagnetic spectrum, measured by the metre and its derived scales. The microwave is between 1 meter to 1 millimeter. The millimetre (American and British English spelling differences#-re, -er, ...

and submillimetre wavelengths, are better at observing

concentrated in interplanetary regions, since stars emit comparatively little light at these wavelengths, and since optical observations are often fraught with overwhelming glare from the bright host star. The circumplanetary disk was detected around a young massive,

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousand ...

-like

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

, PDS 70c; another such disk may have been detected around the related massive, Jupiter-like exoplanet, PDS 70b, as well. These exoplanets are part of the multiplanetary PDS 70 star system, about from Earth. According to Andrea Isella, lead researcher from the

Rice University William Marsh Rice University (Rice University) is a Private university, private research university in Houston, Houston, Texas. It is on a 300-acre campus near the Houston Museum District and adjacent to the Texas Medical Center. Rice is ranke ...

Houston, Texas Houston (; ) is the most populous city in Texas, the most populous city in the Southern United States, the fourth-most populous city in the United States, and the sixth-most populous city in North America, with a population of 2,304,580 i ...

, "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 The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems). It suggests the Solar System is formed from gas and dust orbiting t ...

... By comparing our observations to the high-resolution infrared and

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

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." 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" 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. Possible circumplanetary disks have also been detected around Cha 110913−773444,

2M1207b 2M1207b is a planetary-mass object orbiting the brown dwarf 2M1207, in the constellation Centaurus, approximately 170 light-years from Earth.

J1407b 1SWASP J140747.93−394542.6 (also known as 1SWASP J140747, J1407 and Mamajek's Object) is a star similar to the Sun in the constellation Centaurus at a distance of about 434 light-years from Earth. A relatively young star, its age is estimated to ...

, HD 100546 b, GSC 06214-00210 b, and DH Tauri b.

References

External links

Image Gallery of Circumstellar Dust disks
(

Paul Kalas Paul Kalas (born August 13, 1967) is a Greek American astronomer known for his discoveries of debris disks around stars. Kalas led a team of scientists to obtain the first visible-light images of an extrasolar planet with orbital motion around ...

;
Learning Site
" * ( ESO; July 2021) {{portal bar, astronomy, space

See also

References

External links