EDP Sciences
Free Access
Volume 431, Number 2, February IV 2005
Page(s) 679 - 686
Section Stellar atmospheres
DOI https://doi.org/10.1051/0004-6361:20041201
Published online 04 February 2005

A&A 431, 679-686 (2005)
DOI: 10.1051/0004-6361:20041201

Relationship between X-ray and ultraviolet emission of flares from dMe stars observed by XMM-Newton

U. Mitra-Kraev1, L. K. Harra1, M. Güdel2, M. Audard3, G. Branduardi-Raymont1, H. R. M. Kay1, R. Mewe4, A. J. J. Raassen4, 5 and L. van Driel-Gesztelyi1, 6, 7

1  Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
    e-mail: umk@mssl.ucl.ac.uk
2  Paul Scherrer Institut, Würenlingen & Villigen, 5232 Villigen PSI, Switzerland
3  Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA
4  SRON National Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
5  Astronomical Institute "Anton Pannekoek", Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
6  Observatoire de Paris, LESIA, 92195 Meudon, France
7  Konkoly Observatory, 1525 Budapest, Hungary

(Received 30 April 2004 / Accepted 30 September 2004 )

We present simultaneous ultraviolet and X-ray observations of the dMe-type flaring stars AT Mic , AU Mic , EV Lac , UV Cet and YZ CMi obtained with the XMM-Newton observatory. During 40 h of simultaneous observation we identify 13 flares which occurred in both wave bands. For the first time, a correlation between X-ray and ultraviolet flux for stellar flares has been observed. We find power-law relationships between these two wavelength bands for the flare luminosity increase, as well as for flare energies, with power-law exponents between 1 and 2. We also observe a correlation between the ultraviolet flare energy and the X-ray luminosity increase, which is in agreement with the Neupert effect and demonstrates that chromospheric evaporation is taking place.

Key words: stars: chromospheres -- stars: coronae -- stars: flare -- stars: late-type -- ultraviolet: stars -- X-rays: stars

SIMBAD Objects

© ESO 2005

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.