A Circumplanetary Disk around PDS70c

Abstract

PDS 70 is a unique system in which two protoplanets, PDS 70 b and c, have been discovered within the dustdepleted cavity of their disk, at ∼22 and 34 au, respectively, by direct imaging at infrared wavelengths. Subsequent detection of the planets in the Hα line indicates that they are still accreting material through circumplanetary disks.In this Letter, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum emission at 855 μm at high angular resolution (∼20 mas, 2.3 au) that aim to resolve the circumplanetary disks and constrain their dust masses. Our observations confirm the presence of a compact source of emission colocated with PDS 70 c, spatially separated from the circumstellar disk and less extended than ∼1.2 au in radius, a value close to the expected truncation radius of the circumplanetary disk at a third of the Hill radius. The emission around PDS 70 c has a peak intensity of ∼86 ± 16 μJy beam −1 , which corresponds to a dust mass of ∼0.031 M ⊕ or ∼0.007 M ⊕ , assuming that it is only constituted of 1 μm or 1 mm sized grains, respectively. We also detect extended, low surface brightness continuum emission within the cavity near PDS 70 b. We observe an optically thin inner disk within 18 au of the star with an emission that could result from small micron-sized grains transported from the outer disk through the orbits of b and c. In addition, we find that the outer disk resolves into a narrow and bright ring with a faint inner shoulder.

How binaries accrete: hydrodynamics simulations with passive tracer particles

“…Circumbinary disks are frequent evolutionary accessories to binaries spanning celestial scales. They are observed or expected from small scales around planetmoon systems (Benisty et al 2021), star-planet binaries in protoplanetary nebulae (Ward 1997;Kley & Nelson 2012), and young stellar binaries (Mathieu et al 1997;McCabe et al 2002;Krist et al 2005;Orosz et al 2012) up to much larger scales around massive black hole pairs (Artymowicz & Lubow 1996;Armitage & Natarajan 2002;Milosavljevic & Phinney 2005). The problem of the dynamics and observable signatures of such circumbinary disks has been a central issue in astrophysics for decades because the interaction between the disk and central binary is vital for both the evolution of embedded moons, planets, binary stars, or black holes as well as the identification of such binaries in astronomical surveys.…”

Efficiently Imaging Accreting Protoplanets from Space: Reference Star Differential Imaging of the PDS 70 Planetary System using the HST/WFC3 Archival PSF Library

“…Ground-based high-contrast imaging observations uncovered two planets, PDS 70 b and c, within the disk cavity (Keppler et al 2018;Haffert et al 2019;Wang et al 2020Wang et al , 2021 located at projected separations of 20 and 34 au from the star, respectively. Isella et al (2019) tentatively detected the presence of a circumplanetary disk around PDS 70 c, which was recently confirmed by Benisty et al (2021) using Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum emission at 855 µm.…”

A Simple Time-Dependent Method for Calculating Spirals: Applications to Eccentric Planets in Protoplanetary discs

“…This is similar to PDS 70c (Haffert et al 2019), where the planet is close to the outer gap edge. Then, the planet can potentially accrete more material from the circumstellar disc, facilitating its growth and the circumplanetary disc formation (Isella et al 2019;Benisty et al 2021).…”