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Ground based imaging, imaging polarimetry, and recent Hubble Space Telescope WFPC2 and NICMOS images of protostars have revealed very complex scattered light patterns that cannot be entirely explained by 2-D radiation transfer models. We…

Surface temperature inhomogeneities in classical T Tauri stars (CTTS) induced by magnetic activity and mass accretion lead to rotational modulation of both photometric and spectroscopic parameters of these stars. Using the extended…

Solar and Stellar Astrophysics · Physics 2013-01-23 Svetlana A. Artemenko , Konstantin N. Grankin , Peter P. Petrov

We present 2.0-2.4micron integral field spectroscopy at adaptive optics spatial resolution (~0.''1) obtained with the Near-infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory of six Classical T Tauri stars: T Tau, DG…

Astrophysics · Physics 2009-11-13 Tracy L. Beck , Peter J. McGregor , Michihiro Takami , Tae-Soo Pyo

Classical T Tauri stars (CTTS) exhibit strong variability over timescales of minutes to decades. However, much theoretical work assumes that CTTS are in stable spin states. Here, we test expectations for CTTS angular momentum regulation by…

We present a second paper related to the analyses of high-dispersion spectroscopic observations of the magnetic cataclysmic variable AE Aquarii. We focus our efforts on the study of the emission lines and their radial velocities. We detect…

Solar and Stellar Astrophysics · Physics 2021-12-08 Sergio Ramirez , Juan Echevarria

We have recently obtained polarimetric data at mm wavelengths with ALMA for the young systems DG Tau and CW Tau, for which the rotation properties of jet and disk have been investigated in previous high angular resolution studies. The…

Solar and Stellar Astrophysics · Physics 2019-08-14 F. Bacciotti , J. M. Girart , M. Padovani , L. Podio , R. Paladino , L. Testi , E. Bianchi , D. Galli , C. Codella , D. Coffey , C. Favre , D. Fedele

We present evidence for rotational modulation of X-ray flares by an analysis of four outbursts on late-type stars. Three of these flares have been observed on T Tauri Stars and one on Algol. The structure of the X-ray lightcurves observed…

Astrophysics · Physics 2016-08-30 B. Stelzer , R. Neuhaeuser , S. Casanova , T. Montmerle

The H$\alpha$ profile varies with the orbital period. The two strong shell type emission peaks are identified as from one single broad emission feature with an absorption centered around -7.5~\kms. The intensity variations are largely…

The polarization of tau leptons in the reaction e+ e- --> tau+ tau- has been measured using a e+e- collider, TRISTAN, at the center-of-mass energy of 58 GeV. From the kinematical distributions of daughter particles in tau --> e nu nu-bar,…

High Energy Physics - Experiment · Physics 2009-10-30 H. Hanai

We present Submillimeter Array observations of the Herbig Ae star HD169142 in 1.3 millimeter continuum emission and 12CO J=2-1 line emission at 1.5 arcsecond resolution that reveal a circumstellar disk. The continuum emission is centered on…

Astrophysics · Physics 2008-11-26 A. Raman , M. Lisanti , D. J. Wilner , C. Qi , M. Hogerheijde

The first results from a near-contemporaneous optical and infrared spectroscopic observing program designed to probe the detailed density structure of classical Be circumstellar disks are presented. We report the discovery of asymmetrical…

We study the evolution of circumbinary disks surrounding classical T Tau stars. High resolution numerical simulations are employed to model a system consisting of a central eccentric binary star within an accretion disk. The disk is assumed…

Astrophysics · Physics 2009-11-07 R. Guenther , W. Kley

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…

Recently, differences in Doppler shifts across the base of four close classical T Tauri star jets have been detected with the HST in optical and near-ultraviolet (NUV) emission lines, and these Doppler shifts were interpreted as rotation…

Solar and Stellar Astrophysics · Physics 2016-12-07 F. Louvet , C. Dougados , S. Cabrit , A. Hales , C. Pinte , F. Menard , F. Bacciotti , D. Coffey , D. Mardones , L. Bronfman , F. Gueth

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

Polarized emission is detected in two young nearly edge-on protostellar disks in 343 GHz continuum at ~ 50 au (~ 0.12") resolution with Atacama Large Millimeter/submillimeter Array. One disk is in HH 212 (Class 0) and the other in HH 111…

Astrophysics of Galaxies · Physics 2018-02-28 Chin-Fei Lee , Zhi-Yun Li , Tao-Chung Ching , Shih-Ping Lai , Haifeng Yang

While protoplanetary disks often appear to be compact and well-organized in millimeter continuum emission, CO spectral line observations are increasingly revealing complex behavior at large distances from the host star. We present deep ALMA…

AR Sco is a binary system that contains a white and red dwarf. The rotation rate of the white dwarf has been observed to slow down, analogous to rotation-powered radio pulsars; it has thus been dubbed a "white dwarf pulsar". We previously…

High Energy Astrophysical Phenomena · Physics 2021-12-17 Louis du Plessis , Christo Venter , Zorawar Wadiasingh , Alice K. Harding , David A. H. Buckley , Stephen B. Potter , P. J. Meintjes

We investigate the structure of the O-type binary system HD 48099 by measuring linear polarization that arises due to light scattering process. Linear polarization measurements of HD 48099 in the B, V and R passbands with the high-precision…

Solar and Stellar Astrophysics · Physics 2016-06-02 A. Berdyugin , V. Piirola , S. Sadegi , S. Tsygankov , T. Sakanoi , M. Kagitani , M. Yoneda , S. Okano , J. Poutanen

We have identified 12 Seyfert 1 galaxies that exhibit optical polarization spectra similar to those of Seyfert 2 galaxies in which polarized broad-lines are detected. We present new spectropolarimetric observations of 3 of them: Was 45, Mrk…

Astrophysics · Physics 2008-11-26 J. E. Smith , A. Robinson , D. M. Alexander , S. Young , D. J. Axon , Elizabeth A. Corbett