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T Tauri stars produce broad Lyman-alpha emission lines that contribute $\sim$88% of the total UV flux incident on the inner circumstellar disks. Lyman-alpha photons are generated at the accretion shocks and in the protostellar chromospheres…

It is now accepted that accretion onto classical T Tauri stars is controlled by the stellar magnetosphere, yet to date most accretion models have assumed that their magnetic fields are dipolar. By considering a simple steady state accretion…

Astrophysics · Physics 2009-11-11 S. G. Gregory , M. Jardine , I. Simpson , J. -F. Donati

Magnetospheric accretion is the paradigm for accretion in Classical T-Tauri Stars (CTTS). However, the standard, one-flow magnetospheric accretion model fails to replicate important characteristics such as the observed Balmer decrements. We…

We present a three-dimensional, time-dependent, MHD simulation of the short-term interaction between a protoplanetary disk and the stellar corona in a T Tauri system. The simulation includes the stellar magnetic field, self-consistent…

Solar and Stellar Astrophysics · Physics 2023-06-07 Ofer Cohen , Cecilia Garraffo , Jeremy Drake , Kristina Monsch , Igor Sokolov , Julian Alvarado-Gomez , Federico Fraschetti

We examine the ability of photoevaporative disk winds to explain the low-velocity components observed in the forbidden line spectra of low-mass T Tauri stars. Using the analytic model of Shu, Johnstone, & Hollenbach (1993) and Hollenbach et…

Astrophysics · Physics 2009-11-10 Andreea S. Font , Ian G. McCarthy , Doug Johnstone , David R. Ballantyne

We present the first magnetohydrodynamic model of the stellar chromospheric heating and acceleration of the outer atmospheres of cool evolved stars, using alpha Tau as a case study. We used a 1.5D MHD code with a generalized Ohm's law that…

Solar and Stellar Astrophysics · Physics 2014-09-15 V. S. Airapetian , J. E. Leake , K. G. Carpenter

We conducted a 12-month monitoring campaign of 33 T Tauri stars (TTS) in Taurus. Our goal was to monitor objects that possess a disk but have a weak Halpha line, a common accretion tracer for young stars, to determine whether they host a…

Solar and Stellar Astrophysics · Physics 2017-10-11 Gaspard Duchene , Adam Becker , Yizhe Yang , Herve Bouy , Robert J. De Rosa , Jennifer Patience , Julien H. Girard

Magnetospheric accretion is a key process that shapes the inner disks of T Tauri stars, controlling mass and angular momentum evolution. It produces strong ultraviolet and optical emission that irradiates the planet-forming environment. In…

Classical T Tauri stars with ages of less than 10 Myr possess accretion discs. Magnetohydrodynamic processes at the boundary between the disc and the stellar magnetosphere control the accretion and ejections gas flows. We carried out a long…

The far-ultraviolet (FUV; 912--1700 \AA) radiation field from accreting central stars in Classical T Tauri systems influences the disk chemistry during the period of giant planet formation. Previous efforts to measure the true…

Solar and Stellar Astrophysics · Physics 2021-09-06 Kevin France , Rebecca Schindhelm , Edwin Bergin , Evelyne Roueff , Herve Abgrall

We model the time dependent radio emission from a disk accretion event in a T-Tauri star using 3D, ideal magnetohydrodynamic simulations combined with a gyrosynchrotron emission and radiative transfer model. We predict for the first time,…

Solar and Stellar Astrophysics · Physics 2020-06-17 C. O. G. Waterfall , P. K. Browning , G. A. Fuller , M. Gordovskyy , S. Orlando , F. Reale

The mechanism of angular momentum transport in protoplanetary disks is fundamental to understand the distributions of gas and dust in the disks. The unprecedented, high spatial resolution ALMA observations taken toward HL Tau and subsequent…

Earth and Planetary Astrophysics · Physics 2017-08-23 Yasuhiro Hasegawa , Satoshi Okuzumi , Mario Flock , Neal J. Turner

We analyze the photometric and spectroscopic variability of the classical T Tauri star V2129 Oph over several rotational cycles to test the dynamical predictions of magnetospheric accretion models. The photometric variability and the radial…

T Tauri stars are known to be magnetically active stars subject to strong flares observed in X-rays. These flares are likely due to intense magnetic reconnection events during which a part of the stored magnetic energy is converted into…

High Energy Astrophysical Phenomena · Physics 2024-04-26 Valentin Brunn , Christian Rab , Alexandre Marcowith , Christophe Sauty , Marco Padovani , Chadi Meskini

Observations of T Tauri stars and young brown dwarfs suggest that the accretion rates of their disks scale strongly with the central stellar mass, approximately $\mdot \propto M_*^2$. No dependence of accretion rate on stellar mass is…

Astrophysics · Physics 2008-11-26 Lee Hartmann , Paola D'Alessio , Nuria Calvet , James Muzerolle

Motivated by recent subarcsecond resolution observations of jets from T Tauri stars, we extend the work of \citep{Safier93a, Safier93b} by computing the thermal and ionization structure of self-similar, magnetically-driven, atomic disk…

Astrophysics · Physics 2009-11-07 Paulo J. V. Garcia , Jonathan Ferreira , Sylvie Cabrit , Luc Binette

We present a study of the Ca II K and IR-triplet lines in a sample of Classical T Tauri stars in the Chamaeleon I star-forming region. We study X-shooter spectra of the stars in the sample and find that in some of these stars the Ca II…

We employ a Monte Carlo radiation transfer code to investigate the multi- wavelength photopolarimetric variability arising from a spotted T Tauri star surrounded by a dusty circumstellar disk. Our aim is to assess the ability of the…

Astrophysics · Physics 2009-10-30 Keivan G. Stassun , Kenneth Wood

In the subset of luminous, early-type stars with strong, large-scale magnetic fields and moderate to rapid rotation, material from the star's radiatively driven stellar wind outflow becomes trapped by closed magnetic loops, forming a…

Solar and Stellar Astrophysics · Physics 2017-12-27 Stanley P. Owocki , Steven R. Cranmer

We investigate which properties of protoplanetary disks around T Tauri stars affect the physics and chemistry in the regions where mid- and far-IR water lines originate and their respective line fluxes. We search for diagnostics for future…

Solar and Stellar Astrophysics · Physics 2021-06-04 S. Antonellini , I. Kamp , P. Riviere-Marichalar , R. Meijerink , P. Woitke , W. -F. Thi , M. Spaans , G. Aresu , E. K. H. Lee