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10 results on '"Holzwarth, V. R."'

1. The magnetosphere of the close accreting PMS binary V4046 Sgr AB

Author

Gregory, S. G., Holzwarth, V. R., Donati, J. -F., Hussain, G. A. J., Montmerle, T., Alecian, E., Alencar, S. H. P., Argiroffi, C., Audard, M., Bouvier, J., Damiani, F., Güdel, M., Huenemoerder, D. P., Kastner, J. H., Maggio, A., Sacco, G. G., and Wade, G. A.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present a preliminary 3D potential field extrapolation model of the joint magnetosphere of the close accreting PMS binary V4046 Sgr. The model is derived from magnetic maps obtained as part of a coordinated optical and X-ray observing program., Comment: 2 pages, proceedings of IAUS 302 "Magnetic Fields throughout Stellar Evolution", Biarritz, France, August 2013. CUP, in press

Published
2013
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2. The magnetosphere of the close accreting PMS binary V4046 Sgr

Author

Gregory, S. G., Holzwarth, V. R., Donati, J. -F., Hussain, G. A. J., Montmerle, T., Alecian, E., Alencar, S. H. P., Argiroffi, C., Audard, M., Bouvier, J., Damiani, F., Güdel, M., Huenemoerder, D. P., Kastner, J. H., Maggio, A., Sacco, G. G., and Wade, G. A.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

V4046 Sagittarii AB is a close short-period classical T Tauri binary. It is a circularised and synchronised system accreting from a circumbinary disk. In 2009 it was observed as part of a coordinated program involving near-simultaneous spectropolarimetric observations with ESPaDOnS at the Canada-France-Hawai'i Telescope and high-resolution X-ray observations with XMM-Newton. Magnetic maps of each star were derived from Zeeman-Doppler imaging. After briefly highlighting the most significant observational findings, we present a preliminary 3D model of the binary magnetosphere constructed from the magnetic maps using a newly developed binary magnetic field extrapolation code. The large-scale fields (the dipole components) of both stars are highly tilted with respect to their rotation axes, and their magnetic fields are linked., Comment: Proceedings of the "Physics at the Magnetospheric Boundary" conference, Geneva, June 2013

Published
2013
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3. Hubble Space Telescope Observations of SV Cam: II. First Derivative Lightcurve Modelling using PHOENIX and ATLAS Model Atmospheres

Author

Jeffers, S. V., Aufdenberg, J. P., Hussain, G. A. J., Cameron, A. Collier, and Holzwarth, V. R.

Subjects
Astrophysics
Abstract

The variation of the specific intensity across the stellar disc is essential input parameter in surface brightness reconstruction techniques such as Doppler imaging, where the relative intensity contributions of different surface elements are important in detecting starspots. We use PHOENIX and ATLAS model atmospheres to model lightcurves derived from high precision (S/N ~ 5000) HST data of the eclipsing binary SV Cam (F9V + K4V), where the variation of specific intensity across the stellar disc will determine the contact points of the binary system lightcurve. For the first time we use chi^2 comparison fits to the first derivative profiles to determine the best-fitting model atmosphere. We show the wavelength dependence of the limb darkening and that the first derivative profile is sensitive to the limb-darkening profile very close to the limb of the primary star. It is concluded that there is only a marginal difference (< 1sigma) between the chi^2 comparison fits of the two model atmospheres to the HST lightcurve at all wavelengths. The usefulness of the second derivative of the light-curve for measuring the sharpness of the primary's limb is investigated, but we find that the data are too noisy to permit a quantitative analysis., Comment: 10 pages, 20 figures, accepted by MNRAS

Published
2006
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4. The magnetosphere of the close accreting PMS binary V4046 Sgr

Author

Gregory S. G., Holzwarth V. R., Donati J.-F., Hussain G. A. J., Montmerle T., Alecian E., Alencar S. H. P., Argiroffi C., Audard M., Bouvier J., Damiani F., Güdel M., Huenemoerder D. P., Kastner J. H., Maggio A., Sacco G. G., and Wade G. A.

Subjects
Physics, QC1-999
Abstract

V4046 Sagittarii AB is a close short-period classical T Tauri binary. It is a circularised and synchronised system accreting from a circumbinary disk. In 2009 it was observed as part of a coordinated program involving near-simultaneous spectropolarimetric observations with ESPaDOnS at the Canada-France-Hawai’i Telescope and high-resolution X-ray observations with XMM-Newton. Magnetic maps of each star were derived from Zeeman-Doppler imaging. After briefly highlighting the most significant observational findings, we present a preliminary 3D model of the binary magnetosphere constructed from the magnetic maps using a newly developed binary magnetic field extrapolation code. The large-scale fields (the dipole components) of both stars are highly tilted with respect to their rotation axes, and their magnetic fields are linked.

Published
2014
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5. The magnetosphere of the close accreting PMS binary V4046 Sgr AB

Author

Gregory, S. G., Holzwarth, V. R., Donati, J.-F, Hussain, G. A. J., Montmerle, T., Alecian, E., Alencar, S. H. P., Argiroffi, C., Audard, M., Bouvier, J., Damiani, F., Güdel, M., Huenemoerder, D. P., Kastner, J. H., Maggio, A., Sacco, G. G., Wade, G. A., Gregory, S. G., Holzwarth, V. R., Donati, J.-F, Hussain, G. A. J., Montmerle, T., Alecian, E., Alencar, S. H. P., Argiroffi, C., Audard, M., Bouvier, J., Damiani, F., Güdel, M., Huenemoerder, D. P., Kastner, J. H., Maggio, A., Sacco, G. G., and Wade, G. A.

Abstract

We present a preliminary 3D potential field extrapolation model of the joint magnetosphere of the close accreting PMS binary V4046 Sgr. The model is derived from magnetic maps obtained as part of a coordinated optical and X-ray observing program

Published
2017

6. The magnetosphere of the close accreting PMS binary V4046 Sgr AB

Author

Gregory, S. G., primary, Holzwarth, V. R., additional, Donati, J.-F., additional, Hussain, G. A. J., additional, Montmerle, T., additional, Alecian, E., additional, Alencar, S. H. P., additional, Argiroffi, C., additional, Audard, M., additional, Bouvier, J., additional, Damiani, F., additional, Güdel, M., additional, Huenemoerder, D. P., additional, Kastner, J. H., additional, Maggio, A., additional, Sacco, G. G., additional, and Wade, G. A., additional

Published
2013
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8. Hubble Space Telescope observations of SV Cam – II. First derivative light-curve modelling usingphoenix andatlas model atmospheres.

Author

Jeffers, S. V., Aufdenberg, J. P., Hussain, G. A. J., Cameron, A. Collier, and Holzwarth, V. R.

Subjects
ASTRONOMICAL observations, STAR observations, ASTROPHYSICS, MICROLENSING (Astrophysics), TELESCOPES
Abstract

The variation of the specific intensity across the stellar disc is an essential input parameter in surface brightness reconstruction techniques such as Doppler imaging, where the relative intensity contributions of different surface elements are important in detecting star-spots. We usephoenix andatlas model atmospheres to model light curves derived from high precision (signal-to-noise ratio ≃ 5000) Hubble Space Telescope ( HST) data of the eclipsing binary SV Cam (F9V+K4V), where the variation of specific intensity across the stellar disc will determine the contact points of the binary system light curve. For the first time, we use χ2 comparison fits to the first derivative profiles to determine the best-fitting model atmosphere. We show the wavelength dependence of the limb darkening and that the first derivative profile is sensitive to the limb-darkening profile very close to the limb of the primary star. It is concluded that there is only a marginal difference (<1σ) between the χ2 comparison fits of the two model atmospheres to the HST light curve at all wavelengths. The usefulness of the second derivative of the light curve for measuring the sharpness of the primary's limb is investigated, but we find that the data are too noisy to permit a quantitative analysis. [ABSTRACT FROM AUTHOR]

Published
2006
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9. The magnetosphere of the close accreting PMS binary V4046 Sgr AB

Author

Gregory, S. G., Holzwarth, V. R., Donati, J.-F, Hussain, G. A. J., Montmerle, T., Alecian, E., Alencar, S. H. P., Argiroffi, C., Audard, M., Bouvier, J., Damiani, F., Güdel, M., Huenemoerder, D. P., Kastner, J. H., Maggio, A., Sacco, G. G., Wade, G. A., Gregory, S. G., Holzwarth, V. R., Donati, J.-F, Hussain, G. A. J., Montmerle, T., Alecian, E., Alencar, S. H. P., Argiroffi, C., Audard, M., Bouvier, J., Damiani, F., Güdel, M., Huenemoerder, D. P., Kastner, J. H., Maggio, A., Sacco, G. G., and Wade, G. A.

Abstract

We present a preliminary 3D potential field extrapolation model of the joint magnetosphere of the close accreting PMS binary V4046 Sgr. The model is derived from magnetic maps obtained as part of a coordinated optical and X-ray observing program

10. The magnetosphere of the close accreting PMS binary V4046 Sgr

Author

G. A. J. Hussain, Manuel Güdel, Joel H. Kastner, Antonio Maggio, Evelyne Alecian, Jean-François Donati, Gregg A. Wade, Thierry Montmerle, G. G. Sacco, Costanza Argiroffi, Scott G. Gregory, F. Damiani, David P. Huenemoerder, Volkmar Holzwarth, Jerome Bouvier, Marc Audard, Silvia H. P. Alencar, Gregory, S G, Holzwarth, V R, Donati, J-F, Hussain, G A J, Montmerle T, Alecian, E, Alencar, S H P, Argiroffi, C, Audard, M, Bouvier, J, Damiani, F, Güdel, M, Huenemoerder, D P, Kastner, J H, Maggio, A, Sacco, G G, Wade, G A, Science & Technology Facilities Council, University of St Andrews. University of St Andrews, and University of St Andrews. School of Physics and Astronomy

Subjects
accretion, young stars, QC1-999, Astrophysics::High Energy Astrophysical Phenomena, Magnetosphere, Binary number, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, Telescope, Settore FIS/05 - Astronomia E Astrofisica, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, QC, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, 010308 nuclear & particles physics, Magnetic field, Dipole, Stars, T Tauri star, QC Physics, Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Circumbinary planet
Abstract

V4046 Sagittarii AB is a close short-period classical T Tauri binary. It is a circularised and synchronised system accreting from a circumbinary disk. In 2009 it was observed as part of a coordinated program involving near-simultaneous spectropolarimetric observations with ESPaDOnS at the Canada-France-Hawai'i Telescope and high-resolution X-ray observations with XMM-Newton. Magnetic maps of each star were derived from Zeeman-Doppler imaging. After briefly highlighting the most significant observational findings, we present a preliminary 3D model of the binary magnetosphere constructed from the magnetic maps using a newly developed binary magnetic field extrapolation code. The large-scale fields (the dipole components) of both stars are highly tilted with respect to their rotation axes, and their magnetic fields are linked., Comment: Proceedings of the "Physics at the Magnetospheric Boundary" conference, Geneva, June 2013

Published
2013
Full Text
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