Publications (32)
AD Leo from X-Rays to Radio: Are Flares Responsible for the Heating of Stellar Coronae?
M. Guedel, M. Audard, E. F. Guinan +4
In spring 1999, a long coordinated observing campaign was performed on the flare star AD Leo, including {\it EUVE}, {\it BeppoSAX}, the {\it VLA}, and optical telescopes. The campa…
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…
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…
Stellar Coronae with \textit{XMM-Newton} RGS. I. Coronal Structure
M. Guedel, M. Audard, A. J. den Boggende +16
First results from high-resolution coronal spectroscopy with the {\it XMM-Newton} Reflection Grating Spectrometers (RGS) are reviewed. Five stellar systems (HR 1099, Capella, Procy…
X-ray powerful diagnostics for highly-ionized plasmas: He-like ions
D. Porquet, R. Mewe, J. S. Kaastra +2
The calculations of the ratios of the Helium-like ion X-ray lines from C V to Si XIII are revisited in order to apply the results to density, temperature and ionization process dia…
High-resolution X-ray spectroscopy of Procyon by Chandra and XMM-Newton
A. J. J. Raassen, R. Mewe, M. Audard +6
We report the analysis of the high-resolution soft X-ray spectrum of the nearby F-type star Procyon in the wavelength range from 5 to 175 Angstrom obtained with the Low Energy Tran…
XMM-Newton Probes the Solar Past: Coronal Abundances of Solar Analogs at Different Ages
M. Guedel, M. Audard, A. Sres +5
We present an X-ray spectral analysis of four solar analogs with different ages and magnetic activity levels. We find largely different coronal compositions. The most active stars…
An X-ray and optical study of the cluster A33
S. Colafrancesco, C. R. Mullis, A. Wolter +11
We report the first detailed X-ray and optical observations of the medium-distant cluster A33 obtained with the Beppo-SAX satellite and with the UH 2.2m and Keck II telescopes at M…
The X-ray spectra of the flaring and quiescent states of AT Microscopii observed by XMM-Newton
A. J. J. Raassen, R. Mewe, M. Audard +1
The X-ray spectrum of the late-type M-dwarf binary AT Mic (dM4.5e+dM4.5e) is observed in the wavelength range 1 - 40 Angstrom by means of rgs and epic-mos on board XMM-Newton. Duri…
Relationship between X-ray and ultraviolet emission of flares from dMe stars observed by XMM-Newton
U. Mitra-Kraev, L. K. Harra, M. Guedel +6
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…
Evidence for a heated gas bubble inside the "cooling flow" region of MKW3s
P. Mazzotta, J. S. Kaastra, F. B. Paerels +4
We report on the deep Chandra observation of central r=200kpc region of the cluster of galaxies MKW3s which was previously identified as a moderate cooling flow cluster. The Chandr…
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…
Chandra LETGS Observation of the Active Binary Algol
J. -U. Ness, J. H. M. M. Schmitt, V. Burwitz +2
A high-resolution spectrum obtained with the low-energy transmission grating onboard the Chandra observatory is presented and analyzed. Our analysis indicates very hot plasma with…
The coronal FeXXI 1354.094 line in AB Doradus
O. Vilhu, P. Muhli, R. Mewe +1
The active late-type star AB Doradus was observed in February 1996 with the Goddard High Resolution Spectrograph of the Hubble Space Telescope using the low resolution G140L gratin…
Coronal density diagnostics with Helium-like triplets: CHANDRA--LETGS observations of Algol, Capella, Procyon, Eps Eri, Alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR1099
J. -U. Ness, J. H. M. M. Schmitt, V. Burwitz +5
We present an analysis of ten cool stars (Algol, Capella, Procyon, Eps Eri, Alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR1099) observed with the Low Energy Transmission Grating Spe…
Helium-like triplet density diagnostics: Applications to CHANDRA--LETGS X-ray observations of Capella and Procyon
J. U. Ness, R. Mewe, J. H. M. M. Schmitt +6
Electron density diagnostics based on the triplets of Helium-like CV, NVI, and OVII are applied to the X-ray spectra of Capella and Procyon measured with the Low Energy Transmissio…
X-ray absorption lines in the Seyfert 1 galaxy NGC 5548 discovered with Chandra-LETGS
J. S. Kaastra, R. Mewe, D. A. Liedahl +2
We present for the first time a high-resolution X-ray spectrum of a Seyfert galaxy. The Chandra-LETGS spectrum of NGC 5548 shows strong, narrow absorption lines from highly ionised…
Helium-like ions as powerful X-ray plasma diagnostics
D. Porquet, R. Mewe, A. J. J Raassen +2
We revisited the calculations of the ratios of the Helium-like ion ``triplet'' (resonance, intercombination, and forbidden lines) for Z=6 to 14 (C V, N VI, O VII, Ne IX, Mg XI, Si…
X-ray/UV campaign on the Mrk 279 outflow: density diagnostics in Active Galactic Nuclei using O V K-shell absorption lines
J. S. Kaastra, A. J. J. Raassen, R. Mewe +6
One of the main problems in modeling the ionised outflows in Active Galactic Nuclei is the unknown distance of the outflowing wind to the central source. Only if the density is kno…
Line ratios for Helium-like ions: Applications to collision-dominated plasmas
D. Porquet, R. Mewe, J. Dubau +2
The line ratios R and G of the three main lines of He-like ions (triplet: resonance, intercombination, forbidden lines) are calculated for CV, NVI, OVII, NeIX, MgXI, and SiXIII. Th…
A Study of the Coronal Plasma in RS CVn binary systems: HR 1099 and co
M. Audard, M. Guedel, A. Sres +5
XMM-Newton has been performing comprehensive studies of X-ray luminous RS CVn binary systems in its calibration and guaranteed time programs. We present results from ongoing invest…
AD Leonis: Flares observed by XMM-Newton and Chandra
E. J. M. van den Besselaar, A. J. J. Raassen, R. Mewe +3
The M-dwarf AD Leonis has been observed with the Reflection Grating Spectrometers and the European Photon Imaging Camera aboard XMM-Newton and also with the Low Energy Transmission…
The active binary star IIPeg with BeppoSAX
S. Covino, G. Tagliaferri, R. Pallavicini +2
IIPeg is an ideal target to study stellar activity and flares, since intense and long lasting flares have been frequently detected from this system at all wavelengths. We report he…
High resolution X-Ray spectroscopy of Zeta Puppis with the XMM-Newton Reflection Grating Spectrometer
S. M. Kahn, M. A. Leutenegger, J. Cottam +5
We present the first high resolution X-ray spectrum of the bright O4Ief supergiant star Zeta Puppis, obtained with the Reflection Grating Spectrometer on-board XMM-Newton. The spec…
Wind clumping and the wind-wind collision zone in the Wolf-Rayet binary gamma Velorum
H. Schild, M. Guedel, R. Mewe +7
We present XMM-Newton observations of gamma^2 Velorum (WR 11, WC8+O7.5III, P = 78.53 d), a nearby Wolf-Ray binary system, at its X-ray high and low states. At high state, emission…
Are stellar coronae optically thin in X-rays? - A systematic investigation of opacity effects
J. -U. Ness, J. H. M. M. Schmitt, M. Audard +2
The relevance of resonant scattering (absorption by photo-excitation and re-emission out of the line of sight) in the solar corona has always been discussed controversially. Ratios…
A SAX/LECS X-ray observation of the active binary Capella
F. Favata, R. Mewe, N. S. Brickhouse +3
We present a SAX/LECS X-ray observation of the active binary Capella, the first coronal source observed in the SAX Guest Investigator program. The analysis of this observation, per…
Stellar Coronae with \textit{XMM-Newton} RGS. II. X-ray Variability
M. Audard, M. Guedel, A. J. den Boggende +16
First results from high-resolution coronal spectroscopy of flares with the Reflection Grating Spectrometers on board the \textit{XMM-Newton} satellite are reviewed. Rotational modu…
First Light Measurements of Capella with the Low Energy Transmission Grating Spectrometer aboard the Chandra X-ray Observatory
A. C. Brinkman, C. J. T. Gunsing, J. S. Kaastra +20
We present the first X-ray spectrum obtained by the Low Energy Transmission Grating Spectrometer (LETGS) aboard the Chandra X-ray Observatory. The spectrum is of Capella and covers…
Coronae of Cool Stars
M. Audard, S. A. Drake, M. Güdel +6
We present preliminary results of grating observations of YY Mensae and V824 Arae by Chandra and XMM-Newton. Spectral features are presented in the context of the emission measure…
A Systematic Spectroscopic X-Ray Study of Stellar Coronae with XMM-Newton: Early Results
M. Guedel, M. Audard, K. W. Smith +10
We have been conducting a comprehensive survey of stellar coronae with the XMM-Newton Reflection Grating Spectrometers during the commissioning, calibration, verification, and guar…
High-Resolution X-ray imaging and spectroscopy of SNR N103B
K. J. van der Heyden, E. Behar, J. Vink +5
The X-ray emission from the young supernova remnant (SNR) N103B is measured and analysed using the high-resolution cameras and spectrometers on board XMMM and CHANDRA. The spectrum…