Browsing by Author "Frasca, Antonio"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    A Magnetically Driven Disk Wind in the Inner Disk of PDS 70*
    (IOP Publishing Ltd, 2023) Campbell-White, Justyn; Manara, Carlo F.; Benisty, Myriam; Natta, Antonella; Claes, Rik A. B.; Frasca, Antonio; Bae, Jaehan; Facchini, Stefano; Isella, Andrea; Pérez, Laura; Pinilla, Paola; Sicilia-Aguilar, Aurora; Teague, Richard
    PDS 70 is so far the only young disk where multiple planets have been detected by direct imaging. The disk has a large cavity when seen at submillimeter and near-infrared wavelengths, which hosts two massive planets. This makes PDS 70 the ideal target to study the physical conditions in a strongly depleted inner disk shaped by two giant planets, and in particular to test whether disk winds can play a significant role in its evolution. Using X-Shooter and HARPS spectra, we detected for the first time the wind-tracing [O i] 6300 Å line, and confirm the low-moderate value of mass-accretion rate in the literature. The [O i] line luminosity is high with respect to the accretion luminosity when compared to a large sample of disks with cavities in nearby star-forming regions. The FWHM and blueshifted peak of the [O i] line suggest an emission in a region very close to the star, favoring a magnetically driven wind as the origin. We also detect wind emission and high variability in the He i 10830 Å line, which is unusual for low accretors. We discuss that, although the cavity of PDS 70 was clearly carved out by the giant planets, the substantial inner-disk wind could also have had a significant contribution to clearing the inner disk.
  • Thumbnail Image
    Item
    Twenty-five Years of Accretion onto the Classical T Tauri Star TW Hya
    (IOP Publishing Ltd, 2023) Herczeg, Gregory J.; Chen, Yuguang; Donati, Jean-Francois; Dupree, Andrea K.; Walter, Frederick M.; Hillenbrand, Lynne A.; Johns-Krull, Christopher M.; Manara, Carlo F.; Günther, Hans Moritz; Fang, Min; Schneider, P. Christian; Valenti, Jeff A.; Alencar, Silvia H. P.; Venuti, Laura; Alcalá, Juan Manuel; Frasca, Antonio; Arulanantham, Nicole; Linsky, Jeffrey L.; Bouvier, Jerome; Brickhouse, Nancy S.; Calvet, Nuria; Espaillat, Catherine C.; Campbell-White, Justyn; Carpenter, John M.; Chang, Seok-Jun; Cruz, Kelle L.; Dahm, S. E.; Eislöffel, Jochen; Edwards, Suzan; Fischer, William J.; Guo, Zhen; Henning, Thomas; Ji, Tao; Jose, Jessy; Kastner, Joel H.; Launhardt, Ralf; Principe, David A.; Robinson, Connor E.; Serna, Javier; Siwak, Michal; Sterzik, Michael F.; Takasao, Shinsuke
    Accretion plays a central role in the physics that governs the evolution and dispersal of protoplanetary disks. The primary goal of this paper is to analyze the stability over time of the mass accretion rate onto TW Hya, the nearest accreting solar-mass young star. We measure veiling across the optical spectrum in 1169 archival high-resolution spectra of TW Hya, obtained from 1998–2022. The veiling is then converted to accretion rate using 26 flux-calibrated spectra that cover the Balmer jump. The accretion rate measured from the excess continuum has an average of 2.51 × 10−9 M ⊙ yr−1 and a Gaussian distribution with an FWHM of 0.22 dex. This accretion rate may be underestimated by a factor of up to 1.5 because of uncertainty in the bolometric correction and another factor of 1.7 because of excluding the fraction of accretion energy that escapes in lines, especially Lyα. The accretion luminosities are well correlated with He line luminosities but poorly correlated with Hα and Hβ luminosity. The accretion rate is always flickering over hours but on longer timescales has been stable over 25 years. This level of variability is consistent with previous measurements for most, but not all, accreting young stars.