Accretion disks around T Tauri stars. II - Balmer emission

1989 ◽  
Vol 341 ◽  
pp. 340 ◽  
Author(s):  
Gibor Basri ◽  
Claude Bertout
Keyword(s):  
Accretion Disks ◽  
T Tauri Stars ◽  
T Tauri

scholarly journals T Tauri stars and flare stars: common properties and differences

1990 ◽  
Vol 137 ◽  
pp. 209-213
Author(s):  
I. Appenzeller
Keyword(s):  
Accretion Disks ◽  
T Tauri Stars ◽  
The Other ◽  
Late Type ◽  
Physical Origin ◽  
Other Hand ◽  
T Tauri ◽  
Low Mass ◽  
Flare Stars

T Tauri stars and flare stars are both magnetically active late-type stars of low mass and low to moderate luminosities. The flares observed in these two classes of variables show similar properties and, thus, probably have the same physical origin. On the other hand, at least the majority of the classical T Tauri stars seem to be surrounded by cool, dusty (accretion) disks, which are absent or undetectable in most classical flare stars.

scholarly journals Outflows and particle acceleration in the accretion disks of young stars

2019 ◽  
Vol 201 ◽  
pp. 09004
Author(s):  
Sergey Khaibrakhmanov ◽  
Alexander Dudorov
Keyword(s):  
Particle Acceleration ◽  
Accretion Disks ◽  
High Speed ◽  
Large Scale ◽  
T Tauri Stars ◽  
Radiative Heat Exchange ◽  
Current Layer ◽  
X Rays ◽  
Disk Structure ◽  
T Tauri

Magneto-gas-dynamic (MGD) outflows from the accretion disks of T Tauri stars with fossil large-scale magnetic fileld are investigated. We consider two mechanisms of the outflows: rise of the magnetic flux tubes (MFT) formed in the regions of efficient generation of the toroidal magnetic fileld in the disk due to Parker instability, and acceleration of particles in the current layer formed near the boundary between stellar magnetosphere and the accretion disk. Structure of the disk is calculated using our MGD model of the accretion disks. We simulate dynamics of the MFT in frame of slender flux tube approximation taking into account aerodynamic and turbulent drags, and radiative heat exchange with external gas. Particle acceleration in the current layer is investigated on the basis of Sweet-Parker model of magnetic reconnection. Our calculations show that the MFT can accelerate to velocities up to 50 km s-1 causing periodic outflows from the accretion disks. Estimations of the particle acceleration in the current layer are applied to interpret high-speed jets and X-rays observed in T Tauri stars with the accretion disks.

scholarly journals Dynamo–Action in Accretion Disks

1993 ◽  
Vol 157 ◽  
pp. 185-192
Author(s):  
W. Deinzer
Keyword(s):  
Magnetic Fields ◽  
Accretion Disks ◽  
Cataclysmic Variables ◽  
T Tauri Stars ◽  
Conducting Medium ◽  
Dynamo Action ◽  
T Tauri ◽  
Thin Disks ◽  
Excitation Conditions

Accretion disks are approximated by thin tori and the generation of magnetic fields by torus–dynamos is investigated. Solutions for the general α2ω–dynamo embedded into vacuum and into an ideally conducting medium are presented. Whereas the former solutions are qualitatively similar to those obtained for thin disks, there is a mode for the latter peculiar to torus–geometry. Excitation conditions for torus–dynamos are compared to those realized in accretion disks in cataclysmic variables, around T Tauri stars and in AGN's.

scholarly journals NMA Imaging of Envelopes and Disks around Low Mass Protostars and T Tauri Stars

1997 ◽  
Vol 182 ◽  
pp. 381-390
Author(s):  
Yoshimi Kitamura ◽  
Masao Saito ◽  
Ryohei Kawabe ◽  
Kazuyoshi Sunada
Keyword(s):  
Accretion Disks ◽  
Molecular Clouds ◽  
Protoplanetary Disks ◽  
Hierarchical Structures ◽  
T Tauri Stars ◽  
Mass Star ◽  
Low Mass Stars ◽  
Star Forming ◽  
T Tauri ◽  
Low Mass

We are intensively studying low mass star formation with the radio telescopes at Nobeyama in Japan. Using both the Nobeyama 45 m dish equipped with a 2 × 2 array receiver and the Nobeyama Millimeter Array (NMA), we can cover a very wide spatial range from overall molecular clouds down to compact protoplanetary disks. With the 45 m dish we are investigating hierarchical structures of molecular clouds including star-forming cores. With NMA we are imaging disklike structures (i.e., envelopes, accretion disks, and protoplanetary disks) around protostars and T Tauri stars. Recently, we have completed our survey for dense disklike envelopes around eleven Class 0 & I protostars by NMA. In this paper, we will present our recent results of the disklike envelopes in addition to the previous NMA results of the disks around three T Tauri stars. On the basis of the data, we will discuss the evolution of the disklike structures (dense envelopes → tenuous ones → dispersing ones → accretion disks → protoplanetary ones), and propose a new scenario for the formation of low mass stars.

Accretion disks around T Tauri stars

1988 ◽  
Vol 330 ◽  
pp. 350 ◽  
Author(s):  
Claude Bertout ◽  
Gibor Basri ◽  
Jerome Bouvier
Keyword(s):  
Accretion Disks ◽  
T Tauri Stars ◽  
T Tauri

scholarly journals Disks and Outflows

1989 ◽  
Vol 120 ◽  
pp. 196-209
Author(s):  
Luis F. Rodríguez
Keyword(s):  
Accretion Disks ◽  
Large Scale ◽  
Circumstellar Disks ◽  
Major Axis ◽  
T Tauri Stars ◽  
Bipolar Outflows ◽  
Dense Cores ◽  
T Tauri ◽  
Recent Developments ◽  
The Continuum

AbstractThis paper reviews recent developments in the study of bipolar outflows and their possible collimation by disklike structures. The exciting stars of most bipolar outflows are embedded in dense cores, self-gravitating structures with masses in the range of 1 to 103M⊙. In many cases, these dense cores are flattened, with its major axis aligned perpendicular to the axis of the outflow. These flattened structures, the interstellar toroids, appear to play a role in the large scale (0.1 pc) collimation of the bipolar outflows. However, a considerable number of observations point to the presence of collimation on much smaller scales. In particular, the results of Sargent and collaborators have revealed the existence of circumstellar disks (with radii of ~1000 AU) that are gravitationally bound to their stars. I also review recent models of accretion disks around T Tauri stars have been successful in explaining the general features of the continuum spectra of T Tauri stars from the ultraviolet to the infrared. Some radio results that have not been considered by these models are discussed.

scholarly journals Classical T Tauri stars: accretion, wind, dust

2021 ◽  
Vol 2 (1) ◽  
pp. 1-8
Author(s):  
Petr Petrov
Keyword(s):  
Accretion Disks ◽  
Accretion Rate ◽  
T Tauri Stars ◽  
Evolutionary Stage ◽  
Gas Flows ◽  
Spectroscopic Monitoring ◽  
T Tauri ◽  
Dynamical Parameters ◽  
Wind Flows ◽  
Magnetospheric Accretion

Classical T Tauri stars (CTTS) are at the early evolutionary stage when the processes of planet formation take place in the surrounding accretion disks. Most of the observed activity in CTTS is due to magnetospheric accretion and wind flows. Observations of the accreting gas flows and appearance of the line-dependent veiling of the photospheric spectrum in CTTS are considered. Evidence for the dusty wind causing the observed irregular variability of CTTS is presented. Photometric and spectroscopic monitoring of two CTTS, RY Tau and SU Aur, has been carried out atthe Crimean Astrophysical Observatory since 2013 aimed at studying the dynamics of accretion and wind flows on time scales from days to years. The observed variations in the dynamical parameters may be caused by changes in the accretion rate and in the global magnetic fields of CTTS.

The Infancy of Solar-Type Stars and its Relevance for the Origin of Life

1997 ◽  
Vol 161 ◽  
pp. 267-282 ◽  
Author(s):  
Thierry Montmerle
Keyword(s):  
Main Sequence ◽  
Solar Nebula ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Necessary Condition ◽  
Sequence Evolution ◽  
T Tauri ◽  
Solar Type ◽  
Optical Domain ◽  
The Origin Of Life

AbstractFor life to develop, planets are a necessary condition. Likewise, for planets to form, stars must be surrounded by circumstellar disks, at least some time during their pre-main sequence evolution. Much progress has been made recently in the study of young solar-like stars. In the optical domain, these stars are known as «T Tauri stars». A significant number show IR excess, and other phenomena indirectly suggesting the presence of circumstellar disks. The current wisdom is that there is an evolutionary sequence from protostars to T Tauri stars. This sequence is characterized by the initial presence of disks, with lifetimes ~ 1-10 Myr after the intial collapse of a dense envelope having given birth to a star. While they are present, about 30% of the disks have masses larger than the minimum solar nebula. Their disappearance may correspond to the growth of dust grains, followed by planetesimal and planet formation, but this is not yet demonstrated.

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