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We obtain contemporaneous observations of the surface and corona of AB Dor using ground-based circularly polarised spectra from the Anglo-Australian Telescope and X-ray data from the Chandra satellite. The ground-based data are used to…

The Chandra X-ray observatory monitored the single cool star, AB Doradus, continuously for a period lasting 88ksec (1.98 Prot) in 2002 December with the LETG/HRC-S. The X-ray lightcurve shows significant rotational modulation. It can be…

A fine analysis of spectral line widths and Doppler shifts employing Fourier transform and cross-correlation techniques has been applied to Chandra HETG spectra obtained in 1999 October of the rapidly rotating young star AB Doradus in order…

Solar and Stellar Astrophysics · Physics 2015-06-23 Jeremy J. Drake , Sun Mi Chung , Vinay L. Kashyap , David Garcia-Alvarez

The Chandra X-ray observatory monitored the single cool star, AB Doradus, continuously for a period lasting 88 ksec (1.98 Prot) in 2002 December with the LETG/HRC-S. The X-ray lightcurve shows rotational modulation, with three peaks that…

We re-analyse spectropolarimetric data of AB Dor taken in 1996 December using a surface imaging code that can model the magnetic field of the star as a non-potential current-carrying magnetic field. We find that a non-potential field needs…

Astrophysics · Physics 2009-11-07 G. A. J. Hussain , A. A. van Ballegooijen , M. Jardine , A. Col lier Cameron

We have modelled the X-ray emission from the young rapid rotator AB Doradus (P = 0.514 days) using as a basis Zeeman-Doppler maps of the surface magnetic field. This allows us to reconcile the apparently conflicting observations of a high…

Astrophysics · Physics 2009-11-07 M. Jardine , K. Wood , A. Collier Cameron , J. -F. Donati , D. H. Mackay

By extrapolating from observationally derived surface magnetograms of low-mass stars we construct models of their coronal magnetic fields and compare the 3D field geometry with axial multipoles. AB Dor, which has a radiative core, has a…

Astrophysics · Physics 2009-11-13 S. G. Gregory , M. Jardine , C. Argiroffi , J. -F. Donati

Polar spots are often observed on rapidly-rotating cool stars, but the nature of the magnetic field in these spots is as yet unknown. While Zeeman-Doppler imaging can provide surface magnetic field maps over much of the observed stellar…

Astrophysics · Physics 2009-11-10 T. McIvor , M. Jardine , A. Collier Cameron , K. Wood , J. -F. Donati

Using long-term X-ray observations, we present the short-term and long-term X-ray variability analysis of the ultra-fast rotating active star AB Dor. Flaring events are common in X-ray observations of AB Dor and occupy a substantial portion…

Solar and Stellar Astrophysics · Physics 2024-03-01 Gurpreet Singh , Jeewan C. Pandey

We present a multiwavelength study of AB Doradus, combining modelling that incorporates a spectropolarimetric magnetic field map with 8.4 GHz radio interferometry to measure the coronal extent and density of this young star. We use the…

Solar and Stellar Astrophysics · Physics 2024-04-10 C. E. Brasseur , M. M. Jardine , G. A. J. Hussain

Our understanding of the structure and dynamics of stellar coronae has changed dramatically with the availability of surface maps of both star spots and also magnetic field vectors. Magnetic field extrapolations from these surface maps…

Solar and Stellar Astrophysics · Physics 2015-05-19 Moira Jardine , Jean-Francois Donati , Doris Arzoumanian , Aline de Vidotto

We have modelled the rotational modulation of X-ray emission from T Tauri stars assuming that they have isothermal, magnetically confined coronae. By extrapolating surface magnetograms we find that T Tauri coronae are compact and clumpy,…

Astrophysics · Physics 2009-11-11 S. G. Gregory , M. Jardine , A. Collier Cameron , J. -F. Donati

We have modeled the rotational modulation of X-ray emission from T Tauri stars assuming that they have isothermal, magnetically confined coronae. By extrapolating surface magnetograms we find that T Tauri coronae are compact and clumpy,…

Astrophysics · Physics 2007-05-23 S. G. Gregory , M. Jardine , A. Collier Cameron , J. -F. Donati

We study the chromosphere and corona of the ultra-fast rotator AB Dor A at high temporal and spectral resolution using simultaneous observations with XMM-Newton in the X-rays, VLT/UVES in the optical, and the ATCA in the radio. Our optical…

Solar and Stellar Astrophysics · Physics 2015-06-17 S. Lalitha , B. Fuhrmeister , U. Wolter , J. H. M. M. Schmitt , D. Engels , M. H. Wieringa

Stellar coronal sources have been observed in the past not only for their astrophysical interest in the field of binary system evolution and interaction, but also for their invaluable roles as benchmarks for plasma spectral models and as…

High Energy Astrophysical Phenomena · Physics 2024-01-25 E. Bozzo , D. P. Huenemoerder , M. Falanga , S. Paltani , E. Costantini , J. de Plaa , L. Gu

We investigate the change in stellar magnetic topology across the fully-convective boundary and its effects on coronal properties. We consider both the magnitude of the open flux that influences angular momentum loss in the stellar wind and…

Solar and Stellar Astrophysics · Physics 2012-07-11 Pauline Lang , Moira Jardine , Jean-Francois Donati , Julien Morin , Aline Vidotto

High-precision space-based photometry obtained by the \emph{Kepler} and \emph{TESS} missions has revealed evidence of rotational modulation associated with main sequence (MS) A and late-B type stars. Generally, such variability in these…

Solar and Stellar Astrophysics · Physics 2020-09-30 James Sikora , Gregg Wade , Jason Rowe

Significant progress has been made recently in our understanding of the structure of stellar magnetic fields, thanks to advances in detection methods such as Zeeman-Doppler Imaging. The extrapolation of this surface magnetic field into the…

Solar and Stellar Astrophysics · Physics 2015-05-19 Doris Arzoumanian , Moira Jardine , Jean-François Donati , Julien Morin , Colin Johnstone

Our study focuses on analysing the coronal, transition and chromospheric activity of four rapidly rotating stars located within 50 pc in the solar neighbourhood. We have used the multi-wavelength capabilities of AstroSat, to investigate the…

Solar and Stellar Astrophysics · Physics 2023-09-21 Lalitha Sairam , Utkarsh Pathak , Kulinder Pal Singh

Spectroscopy with the Chandra High Energy Transmission Grating Spectrometer provides details on X-ray emission and activity from young and cool stars through resolution of emission lines from a variety of ions. We are beginning to see…

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