Article
Astronomy & Astrophysics
Chunhua Zhu, Helei Liu, Zhaojun Wang, Guoliang Lu
Summary: This study investigated the formation of DB WDs and the effects of input parameters on the structures of these WDs. It discussed the impacts of various factors on the element abundances of WD surfaces and compared theoretical models with observations to understand the evolutionary sequence of heavy element abundance on DBZ WD surfaces. Results showed that input parameters had minimal effects on DB WD structures, while mass-accretion rate and effective temperature were key determinants of heavy element abundances on WD surfaces.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
C. P. Dullemond, A. Ziampras, D. Ostertag, C. Dominik
Summary: Through hydrodynamic simulations of protoplanetary disks, it has been determined that disks with geometrically thin midplane dust layers cannot have vertical shear instability (VSI). These findings are significant for understanding dust growth and disk evolution processes.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Ayaka Okuya, Shigeru Ida, Ryuki Hyodo, Satoshi Okuzumi
Summary: A growing number of debris discs around metal-polluted white dwarfs have been detected. They are believed to originate from tidally disrupted exoplanetary bodies and contribute to the accretion of metals onto the white dwarfs. Previous studies proposed that the high accretion rates and the presence of rocky materials in the photosphere can be explained by the runaway accretion of silicate particles due to gas drag. However, this study shows that if re-condensation is taken into account, runaway accretion does not occur and the accretion rate is limited. Alternatively, the presence of volatile gas, such as water vapor, enhances the silicate accretion rate through gas drag and can explain the observed refractory-rich accretion.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Matias Garate, Til Birnstiel, Paola Pinilla, Sean M. Andrews, Raphael Franz, Sebastian Markus Stammler, Giovanni Picogna, Barbara Ercolano, Anna Miotello, Nicolas T. Kurtovic
Summary: In this study, the impact of photoevaporation and dust trapping on the dust distribution and flux in protoplanetary disks is investigated. It is found that disks with early substructures retain more dust and have a brighter millimeter continuum. The results are consistent with the properties of transition disks, suggesting a connection between these two processes.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Matias Garate, Timmy N. Delage, Jochen Stadler, Paola Pinilla, Til Birnstiel, Sebastian Markus Stammler, Giovanni Picogna, Barbara Ercolano, Raphael Franz, Christian Lenz
Summary: By incorporating a dead zone and X-ray photoevaporation into disk evolution models, researchers found that this combination can explain high accretion rates and large gaps observed in transition disks. The study showed that inner disks persist while outer disks disperse rapidly, replicating the observed properties effectively.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Rachel E. Harrison, Leslie W. Looney, Ian W. Stephens, Zhi-Yun Li, Richard Teague, Richard M. Crutcher, Haifeng Yang, Erin G. Cox, Manuel Fernandez-Lopez, Hiroko Shinnaga
Summary: Magnetic fields likely drive the evolution of protoplanetary disks, but observational evidence is limited. Dust continuum linear polarization is more consistent with dust scattering rather than magnetically aligned grains. Zeeman splitting in molecular lines offers a direct measure of magnetic field strength in disks.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
L. Gehrig, T. Steindl, E. I. Vorobyov, R. Guadarrama, K. Zwintz
Summary: This study combines the numerical treatment of a hydrodynamic disk with stellar evolution to investigate the effects of metallicity on the evolution of young stars and accretion disks. It finds that low-metallicity disks are heated differently and have shorter lifetimes, and low-metallicity stars rotate more rapidly. The results provide additional explanations for the observed short disk lifetimes in low-metallicity clusters.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. Gehrig, D. Steiner, E. Vorobyov, M. Guedel
Summary: The study aims to investigate the influence of hydrodynamic disk evolution on stellar rotational period and vice versa during the accretion phase. By combining the TAPIR disk code with a stellar spin evolution model, the research can reproduce the observed fast and slow rotating stars in young stellar clusters within a defined parameter space.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
O. Schib, C. Mordasini, R. Helled
Summary: This article investigates the orbital migration and gas accretion processes of planets in protoplanetary discs. The authors develop a simple prescription for migration and accretion in 1D disc models, calibrated with results from 3D hydrodynamic simulations. The results show that the 1D model is in good agreement with the 3D simulations for a range of parameters.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
P. Pinilla, N. T. Kurtovic, M. Benisty, C. F. Manara, A. Natta, E. Sanchis, M. Tazzari, S. M. Stammler, L. Ricci, L. Testi
Summary: The frequency of Earth-sized planets in habitable zones appears to be higher around M-dwarfs, making these systems exciting laboratories to investigate planet formation. Observations of protoplanetary disks around very low-mass stars and brown dwarfs remain challenging and little is known about their properties. The characteristics of the disk around CIDA 1 challenge current dust evolution models, particularly processes like fragmentation, growth, and diffusion of particles inside pressure bumps.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Paola Pinilla, Christian T. Lenz, Sebastian M. Stammler
Summary: Recent laboratory experiments show that lower fragmentation velocities of icy dust particles can impact planet formation, making it difficult for pebble-sized particles to form in protoplanetary disks. By studying dust evolution models and observing protoplanetary disks, a better understanding of the basic features and structures of these disks can be gained through different combinations of particle and gas diffusion parameters.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Jesse Weder, Christoph Mordasini, Alexandre Emsenhuber
Summary: This study investigates the evolution of large protoplanetary disc populations under the influence of magnetically driven disc winds, internal and external photoevaporation. The simulations show that both strong magnetic torques and weak magnetic winds are necessary to reproduce observed stellar accretion rates. The study also supports the importance of external photoevaporation in disc evolution and its potential influence on planetary formation.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Etienne Martel, Geoffroy Lesur
Summary: This study uses numerical simulations to propose that some transition discs (TDs) may be influenced by magnetised disc winds, which could explain their fast accretion and long-lived cavities. The simulations show that material in the cavity is accreted at sonic velocities, while the cavity itself rotates at a high speed due to magnetic braking.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Lehmann, M-K Lin
Summary: The standard core accretion model for planetesimal formation in protoplanetary discs faces challenges due to the vertical settling of dust against turbulent stirring. The vertical shear instability (VSI), sustaining turbulence in the outer regions of PPDs, drives the formation of long-lived vortices that can collect dust and potentially trigger the streaming instability (SI). The presence of pressure bumps in the discs can lead to the formation of dusty vortices with high dust-to-gas ratios, impacting the vertical mass flow profile and alpha viscosity values.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Sebastiano Ledda, Camilla Danielski, Diego Turrini
Summary: This study explores the formation process and characteristics of planets in circumbinary discs around double white dwarfs (DWDs), with particular attention to gas giant planets. The simulations show that planetary formation is possible in circumbinary discs, but the formation of gas giant planets is hindered by disc temperatures and rapid depletion.
ASTRONOMY & ASTROPHYSICS
(2023)