341 citations · 3.7k across the 91 of their papers we have counts for
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The Sun in Time: Activity and Environment
M. Guedel
(abridged) The Sun's magnetic activity has steadily declined during its main-sequence life. While the solar photospheric luminosity was about 30% lower 4.6 Gyr ago when the Sun arr…
The XMM-Newton Optical Monitor Survey of the Taurus Molecular Cloud
Marc Audard, Kevin Briggs, Nicolas Grosso +4
The Optical Monitor (OM) on-board XMM-Newton obtained optical/ultraviolet data for the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST), simultaneously with the X-ra…
On Temperature and Abundance Effects During an X-Ray Flare on Sigma Geminorum
R. Nordon, E. Behar, M. Guedel
We compare quiescent and flare X-ray spectra of the RS CVn binary Sigma Gem obtained with the Chandra and XMM-Newton grating spectrometers. We find that in addition to an overall 2…
Flare Heating in Stellar Coronae
Vinay Kashyap, Jeremy Drake, Manuel Guedel +1
We investigate the contribution of very weak flares to the coronal luminosity of low-mass active stars. We analyze EUVE/DS events data from FK Aqr, V1054 Oph, and AD Leo and conclu…
XMM-Newton and VLA Observations of the Variable Wolf-Rayet Star EZ CMa: Evidence for a Close Companion?
S. L. Skinner, S. A. Zhekov, M. Guedel +1
We present new X-ray and radio observations of the WR star EZ CMa (HD 50896) obtained with XMM-Newton and the VLA. This WN4 star shows optical/UV variability at a period of 3.76 d…
Stellar Radio Astronomy. Probing Stellar Atmospheres from Protostars to Giants
Manuel Guedel
Radio astronomy has provided evidence for the presence of ionized atmospheres around almost all classes of non-degenerate stars. Magnetically confined coronae dominate in the cool…
Detection of the Neupert Effect in the Corona of an RS CVn Binary System by XMM-Newton and the VLA
M. Guedel, M. Audard, K. W. Smith +3
The RS CVn-type binary Geminorum was observed during a large, long-duration flare simultaneously with {\it XMM-Newton} and the VLA. The light curves show a characteristic time…
XMM-Newton Detection of Hard X-ray Emission in the Nitrogen-Type Wolf-Rayet Star WR110
S. L. Skinner, S. A. Zhekov, M. Guedel +1
We have used the excellent sensitivity of XMM-Newton to obtain the first high-quality X-ray spectrum of a Wolf-Rayet (WR) star which is not known to be a member of a binary system.…
A Study of the Coronal Plasma in RS CVn binary systems
M. Audard, M. Guedel, A. Sres +5
XMM-Newton has been performing comprehensive studies of X-ray bright RS CVn binaries in its Calibration and Guaranteed Time programs. We present results from ongoing investigations…
First Light Measurements with the XMM-Newton Reflection Grating Spectrometers: Evidence for an Inverse First Ionisation Potential Effect and Anomalous Ne A bundance in the Coronae of HR 1099
A. C. Brinkman, E. Behar, M. Guedel +15
The RS CVn binary system HR 1099 was extensively observed by the XMM-Newton observatory in February 2000 as its first-light target. A total of 570 ks of exposure time was accumulat…
The Active Corona of HD 35850 (F8 V)
Marc Gagne, Jeff A. Valenti, Jeffrey L. Linsky +3
We present Extreme Ultraviolet Explorer spectroscopy and photometry of the nearby F8 V star HD 35850 (HR 1817). The EUVE spectra reveal 28 emission lines from Fe IX and Fe XV to Fe…