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Protoplanetary disks and hard X-rays

Published online by Cambridge University Press:  21 October 2010

Eric D. Feigelson ,
Philip J. Armitage  and
Konstantin V. Getman
Eric D. Feigelson
Affiliation:
Dept. of Astronomy and Astrophysics, Penn State University, University Park PA 16802
Philip J. Armitage
Affiliation:
JILA, Campus Box 440, University of Colorado, Boulder CO 80309 Dept. of Astrophysical and Planetary Sciences, University of Colorado, Boulder CO 80309
Konstantin V. Getman
Affiliation:
Dept. of Astronomy and Astrophysics, Penn State University, University Park PA 16802
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The physics of protoplanetary disks and the early stages of planet formation is strongly affected by the level of ionization of the largely-neutral gas (Armitage 2009; Balbus 2009). Where the ionization fraction is above some limit around ~ 10−12, the magnetorotational instability (MRI) will ensue and the gas will become turbulent. The presence or absence of disk turbulence at various locations and times has profound implications for viscosity, accretion, dust settling, protoplanet migration and other physical processes. The dominant source of ionization is very likely X-rays from the host star (Glassgold et al. 2000). X-ray emission is elevated in all pre-main sequence stars primarily due to the magnetic reconnection flares similar to, but much more powerful and frequent than, flares on the surface of the contemporary Sun (Feigelson et al. 2007).

Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 5 , Highlights H15: Highlights of Astronomy , November 2009 , pp. 744
Copyright
Copyright © International Astronomical Union 2010

References

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