0000000000315246
AUTHOR
F. M. Walter
Testing the Ability of Field Extrapolation Models to Predict the X-ray Emission Properties of Pre-Main Sequence Stars
By extrapolating from observationally derived magnetic surface maps, obtained through Zeeman-Doppler imaging, models of stellar magnetospheres can be constructed. By assuming that the plasma trapped along the closed field lines is in hydrostatic equilibrium, coronal X-ray emission properties, such as the global X-ray emission measure and the amount of rotational modulation of X-ray emission, can be predicted. For pre-main sequence magnetospheres the analysis can be extended to incorporate accretion flows, and predict the amount of softer X-ray emission from accretion spots that would be observed. I will detail the preliminary results of an ambitious multi-wavelength, multi-observing site, a…
Surface and Atmospheric Structure on the T Tauri Star V2129 Oph
We provide an overview of a multi-wavelength observing campaign focusing on the accretion and coronal processes in the young star V2129 Oph. V2129 Oph is a classical T Tauri star with a 6.5 day rotation period in the ρ Oph star forming region. On 27-29 June 2009 we obtained two 100 ksec Chandra HETG exposures, aiming at opposite hemispheres of the star. We discuss the X-ray data elsewhere. In order to place the coronal X-ray emission in context, we obtained contemporaneous optical and near-IR photometry and high dispersion optical spectroscopy. The photometry shows the existence of dark photospheric spots. The Hα line profiles show a modulation of the mean Hα velocity and the presence of re…
Multi-wavelength observing of a forming solar-like star
V2129 Oph is a 1.35 solar mass classical T Tauri star, known to possess a strong and complex magnetic field. By extrapolating from an observationally derived magnetic surface map, obtained through Zeeman-Doppler imaging, models of V2129 Oph's corona have been constructed, and used to make predictions regarding the global X-ray emission measure, the amount of modulation of X-ray emission, and the density of accretion shocks. In late June 2009 we will under take an ambitious multi-wavelength, multi-observing site, and near contemporaneous campaign, combining spectroscopic optical, nIR, UV, X-ray, spectropolarimetric and photometric monitoring. This will allow the validity of the 3D field topo…
Variable X-ray emission from the accretion shock in the classical T Tauri star V2129 Ophiuchi
The soft X-ray emission from high density plasma in CTTS is associated with the accretion process. It is still unclear whether this high density cool plasma is heated in the accretion shock, or if it is coronal plasma fed/modified by the accretion process. We conducted a coordinated quasi-simultaneous optical and X-ray observing campaign of the CTTS V2129 Oph (Chandra/HETGS data to constrain the X-ray emitting plasma components, and optical observations to constrain the characteristics of accretion and magnetic field). We analyze a 200 ks Chandra/HETGS observation of V2129 Oph, subdivided into two 100 ks segments, corresponding to two different phases within one stellar rotation. The X-ray …