Browsing by Author "Facchini, Stefano"
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- ItemMolecules with ALMA at Planet-forming Scales (MAPS): A Circumplanetary Disk Candidate in Molecular-line Emission in the AS 209 Disk(2022) Bae, Jaehan; Teague, Richard; Andrews, Sean M.; Benisty, Myriam; Facchini, Stefano; Galloway-Sprietsma, Maria; Loomis, Ryan A.; Aikawa, Yuri; Alarcon, Felipe; Bergin, Edwin; Bergner, Jennifer B.; Booth, Alice S.; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Guzman, Viviana V.; Huang, Jane; Ilee, John D.; Kurtovic, Nicolas T.; Law, Charles J.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Oberg, Karin, I; Perez, Laura M.; Qi, Chunhua; Schwarz, Kamber R.; Sierra, Anibal; Walsh, Catherine; Wilner, David J.; Zhang, KeWe report the discovery of a circumplanetary disk (CPD) candidate embedded in the circumstellar disk of the T Tauri star AS 209 at a radial distance of about 200 au (on-sky separation of 1.'' 4 from the star at a position angle of 161 degrees), isolated via (CO)-C-13 J = 2-1 emission. This is the first instance of CPD detection via gaseous emission capable of tracing the overall CPD mass. The CPD is spatially unresolved with a 117 x 82 mas beam and manifests as a point source in (CO)-C-13, indicating that its diameter is less than or similar to 14 au. The CPD is embedded within an annular gap in the circumstellar disk previously identified using (CO)-C-12 and near-infrared scattered-light observations and is associated with localized velocity perturbations in (CO)-C-12. The coincidence of these features suggests that they have a common origin: an embedded giant planet. We use the (CO)-C-13 intensity to constrain the CPD gas temperature and mass. We find that the CPD temperature is greater than or similar to 35 K, higher than the circumstellar disk temperature at the radial location of the CPD, 22 K, suggesting that heating sources localized to the CPD must be present. The CPD gas mass is greater than or similar to 0.095 M (Jup) similar or equal to 30 M (circle plus) adopting a standard (CO)-C-13 abundance. From the nondetection of millimeter continuum emission at the location of the CPD (3 sigma flux density less than or similar to 26.4 mu Jy), we infer that the CPD dust mass is less than or similar to 0.027 M (circle plus) similar or equal to 2.2 lunar masses, indicating a low dust-to-gas mass ratio of less than or similar to 9 x 10(-4). We discuss the formation mechanism of the CPD-hosting giant planet on a wide orbit in the framework of gravitational instability and pebble accretion.
- ItemMolecules with ALMA at Planet-forming Scales (MAPS): Complex Kinematics in the AS 209 Disk Induced by a Forming Planet and Disk Winds(2023) Galloway-Sprietsma, Maria; Bae, Jaehan; Teague, Richard; Benisty, Myriam; Facchini, Stefano; Aikawa, Yuri; Alarcon, Felipe; Andrews, Sean M.; Bergin, Edwin; Cataldi, Gianni; Cleeves, L. Ilsedore; Czekala, Ian; Guzman, Viviana V.; Huang, Jane; Law, Charles J.; Le Gal, Romane; Liu, Yao; Long, Feng; Menard, Francois; Oberg, Karin I.; Walsh, Catherine; Wilner, David J.We study the kinematics of the AS 209 disk using the J = 2-1 transitions of (CO)-C-12, (CO)-C-13, and (CO)-O-18. We derive the radial, azimuthal, and vertical velocity of the gas, taking into account the lowered emission surface near the annular gap at similar or equal to 1.'' 7 (200 au) within which a candidate circumplanetary-disk-hosting planet has been reported previously. In (CO)-C-12 and (CO)-C-13, we find a coherent upward flow arising from the gap. The upward gas flow is as fast as 150 m s(-1) in the regions traced by (CO)-C-12 emission, which corresponds to about 50% of the local sound speed or 6% of the local Keplerian speed. Such an upward gas flow is difficult to reconcile with an embedded planet alone. Instead, we propose that magnetically driven winds via ambipolar diffusion are triggered by the low gas density within the planet-carved gap, dominating the kinematics of the gap region. We estimate the ambipolar Elsasser number, Am, using the HCO+ column density as a proxy for ion density and find that Am is similar to 0.1 at the radial location of the upward flow. This value is broadly consistent with the value at which numerical simulations find that ambipolar diffusion drives strong winds. We hypothesize that the activation of magnetically driven winds in a planet-carved gap can control the growth of the embedded planet. We provide a scaling relationship that describes the wind-regulated terminal mass: adopting parameters relevant to 100 au from a solar-mass star, we find that the wind-regulated terminal mass is about one Jupiter mass, which may help explain the dearth of directly imaged super-Jovian-mass planets.