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X-rays from accretion shocks in classical T Tauri stars: 2D MHD modeling and the role of local absorption

Published online by Cambridge University Press:  07 August 2014

C. Argiroffi
Affiliation:
Dip. di Fisica e Chimica, Università di Palermo, Palermo, Italy, email: argi@astropa.unipa.it INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
R. Bonito
Affiliation:
Dip. di Fisica e Chimica, Università di Palermo, Palermo, Italy, email: argi@astropa.unipa.it
S. Orlando
Affiliation:
INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
M. Miceli
Affiliation:
INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
F. Reale
Affiliation:
Dip. di Fisica e Chimica, Università di Palermo, Palermo, Italy, email: argi@astropa.unipa.it INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
G. Peres
Affiliation:
Dip. di Fisica e Chimica, Università di Palermo, Palermo, Italy, email: argi@astropa.unipa.it INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
T. Matsakos
Affiliation:
CEA, IRAMIS, Service Photons, Atomes et Molécules, Gif-sur-Yvette, France Laboratoire AIM, CEA/DSM - CNRS - Université Paris Diderot, IRFU/SAp, Gif-sur-Yvette, France
C. Sthelé
Affiliation:
LERMA, Observatoire de Paris, Universitè Pierre et Marie Curie, CNRS, 5 place J. Janssen, Meudon, France.
L. Ibgui
Affiliation:
LERMA, Observatoire de Paris, Universitè Pierre et Marie Curie, CNRS, 5 place J. Janssen, Meudon, France.
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Abstract

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In classical T Tauri stars (CTTS) strong shocks are formed where the accretion funnel impacts with the denser stellar chromosphere. Although current models of accretion provide a plausible global picture of this process, some fundamental aspects are still unclear: the observed X-ray luminosity in accretion shocks is order of magnitudes lower than predicted; the observed density and temperature structures of the hot post-shock region are puzzling and still unexplained by models.

To address these issues we performed 2D MHD simulations describing an accretion stream impacting onto the chromosphere of a CTTS, exploring different configurations and strengths of the magnetic field. From the model results we then synthesized the X-ray emission emerging from the hot post-shock, taking into account the local absorption due to the pre-shock stream and surrounding atmosphere.

We find that the different configurations and strengths of the magnetic field profoundly affect the hot post-shock properties. Moreover the emerging X-ray emission strongly depends also on the viewing angle under which accretion is observed. Some of the explored configuration are able to reproduce the observed features of X-ray spectra of CTTS.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2014 

References

Mignone, A., Bodo, G., Massaglia, S., Matsakos, T., Tesileanu, O., Zanni, C., & Ferrari, A. 2007, ApJS, 170, 228CrossRefGoogle Scholar
Orlando, S., Bonito, R., Argiroffi, C., et al. 2012, A&A, in pressGoogle Scholar