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Simulations and analytic arguments suggest that the turbulence driven by magnetorotational instability (MRI) in accretion discs can amplify the toroidal (azimuthal) component of the magnetic field to a point at which magnetic pressure…

Astrophysics · Physics 2008-11-26 M. C. Begelman , J. E. Pringle

We present results of axisymmetic magnetohydrodynamic simulations of the interaction of a rapidly-rotating, magnetized star with an accretion disk. The disk is considered to have a finite viscosity and magnetic diffusivity. The main…

Astrophysics · Physics 2009-11-11 G. V. Ustyugova , A. V. Koldoba , M. M. Romanova , R. V. E. Lovelace

We estimate the accretion rates of 235 Classical T Tauri star (CTTS) candidates in the Lagoon Nebula using $ugri$H$\alpha$ photometry from the VPHAS+ survey. Our sample consists of stars displaying H$\alpha$-excess, the intensity of which…

We present radial-velocity measurements obtained using high- and intermediate-resolution spectroscopic observations of the classical T Tauri star UZ Tau East obtained from 1994 to 1996. We also provide measurements of H$\alpha$ equivalent…

Astrophysics · Physics 2009-11-10 Eduardo L. Martín , Antonio Magazzù , Xavier Delfosse , Robert D. Mathieu

We have simultaneously monitored the photometric and polarimetric variations of the Classical T Tauri star AA Tau during the fall of 2002. We combine these data with previously published polarimetric data covering two earlier epochs. The…

Astrophysics · Physics 2009-11-10 F. Menard , J. Bouvier , C. Dougados , S. Y. Mel'nikov , K. N. Grankin

An investigation of the magnetospheric accretion and outflow signatures in sub-stellar objects is a natural extension of similar studies conducted on classical T Tauri stars (CTTS), and helps understand if brown dwarfs (BDs) follow the same…

Solar and Stellar Astrophysics · Physics 2013-07-08 B. Riaz

While the rate of accretion onto T Tauri stars is predicted to decline with age, objects with strong accretion have been detected up to ages of 10 Myr. We analyze a sample of these old accretors identified by having a significant $U$ band…

Solar and Stellar Astrophysics · Physics 2015-06-19 Laura Ingleby , Nuria Calvet , Jesus Hernandez , Cesar Briceno , Jon Miller , Catherine Espaillat , Melissa McClure

We investigate whether the magnetic field of an accreting neutron star may be diamagnetically screened by the accreted matter. We assume the freshly accumulated material is unmagnetized, and calculate the rate at which the intrinsic stellar…

Astrophysics · Physics 2009-11-06 Andrew Cumming , Ellen G. Zweibel , Lars Bildsten

This work presents a study of the evolution of the stellar accretion rates of pre-main-sequence intermediate-mass stars. We compare the accretion rate of the younger intermediate-mass T Tauri stars (IMTTSs) with the older Herbig stars into…

Solar and Stellar Astrophysics · Physics 2025-12-03 Sean D. Brittain , Joshua W. Kern , Gwendolyn Meeus , Rene D. Oudmaijer

The interaction between a protostellar magnetosphere and a surrounding dynamo-active accretion disc is investigated using an axisymmetric mean-field model. In all models investigated, the dynamo-generated magnetic field in the disc arranges…

Astrophysics · Physics 2009-11-10 Brigitta von Rekowski , Axel Brandenburg

Studies of the stellar and accretion properties of classical T Tauri stars (CTTS) require comparison with photospheric spectral templates. Here we aim at expanding the currently available grid of wide-wavelength coverage observed spectra of…

Over two hundred protoplanetary disk systems have been resolved by ALMA, and the vast majority suggest the presence of planets. The dust gaps in transition disks are considered evidence of giant planets sculpting gas and dust under…

Earth and Planetary Astrophysics · Physics 2024-06-05 Yinhao Wu

We have used the high sensitivity and resolution of the IRAM interferometer to produce sub-arcsecond 12CO 2-1 images of 9 protoplanetary disks surrounding T Tauri stars in the Taurus-Auriga cloud (7 singles and 2 binaries). The images…

Astrophysics · Physics 2009-06-16 M. Simon , A. Dutrey , S. Guilloteau

We present results of fully three-dimensional MHD simulations of disk accretion to a rotating magnetized star with its dipole moment inclined at an angle Theta to the rotation axis of the disk. We observed that matter accretes from the disk…

Studying the physical processes occurring in the region just above the magnetic poles of strongly magnetized, accreting binary neutron stars is essential to our understanding of stellar and binary system evolution. Perhaps more importantly,…

Light curves of young star systems show photometric variability due to different kinematic, and physical processes. One of the main contributors to the photometric variability is the changing mass accretion rate, which regulates the…

Solar and Stellar Astrophysics · Physics 2022-10-26 Eleonora Fiorellino , Gabriella Zsidi , Agnes Kospal , Peter Abraham , Attila Bodi , Gaitee Hussain , Carlo F. Manara , Andras Pal

Simulations of the collapse and fragmentation of turbulent molecular clouds and dense young clusters show that encounters between disc-surrounded stars are relatively common events which should significantly influence the resulting disc…

Astrophysics · Physics 2009-11-11 S. Pfalzner , S. Umbreit , Th. Henning

A new experimental set-up designed to investigate the accretion dynamics in newly born stars is presented. It takes advantage of a magnetically collimated stream produced by coupling a laser-generated expanding plasma to a $2\times…

Solar and Stellar Astrophysics · Physics 2019-09-27 G. Revet , B. Khiar , J. Béard , R. Bonito , S. Orlando , M. V. Starodubtsev , A. Ciardi , J. Fuchs

The results of three-dimensional MHD numerical simulations are used to investigate the characteristic properties of the magnetic-field structures in the accretion disks of semi-detached binary systems. It is assumed that the intrinsic…

Solar and Stellar Astrophysics · Physics 2010-07-21 A. G. Zhilkin , D. V. Bisikalo

Close binary systems present challenges to planet formation. As binary separations decrease, so too do the occurrence rates of protoplanetary disks in young systems and planets in mature systems. For systems that do retain disks, their disk…

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