Circumplanetary disk

In August 2018, astronomers reported the probable detection of a circumplanetary disk around CS Cha B.

The older models at the time were not consistent with the icy composition of the moons and the incomplete differentiation of Callisto.

A circumplanetary disk with an inflow of 2*10−7 MJ/year of gas and solids was consistent with the conditions needed to form the moons, including the low temperature during the late stage of the formation of Jupiter.

[28] New observations from JWST/NIRSpec were able to confirm accretion from an unseen disk by detecting emission from hydrogen and helium.

[30] In June 2019 astronomers reported the detection of evidence of a circumplanetary disk around PDS 70b[31] using spectroscopy and accretion signatures.

[32] Interferometric observations with JWST NIRISS and archived data found that PDS 70b has a circumplanetary disk.

[33] In July 2019 astronomers reported the first-ever detection using the Atacama Large Millimeter/submillimeter Array (ALMA)[34][35][36] of a circumplanetary disk.

[34][35][37] 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.

[34][35][37] 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 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.

"[36] 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"[38] then the signal around PDS 70c needs to be spatially separated from the outer ring, not the case in 2019.

[39] 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.

Part of this spiral-like feature was interpreted as an accretion stream that feeds the circumplanetary disk around PDS 70c.