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The peculiar cooling flow cluster RX J0820.9+0752
Fabian, A. C.; Allen, S. W.; Edge, A. C. +2 more
We present observations of the cluster of galaxies associated with the X-ray source RX J0820.9+0752 and its dramatic central cluster galaxy in the optical and X-ray wavebands. Unlike other cooling flow central cluster galaxies studied in detail, this system does not contain a powerful radio source at its core, and so provides us with an important …
XMM-Newton and Very Large Array Observations of the Variable Wolf-Rayet Star EZ Canis Majoris: Evidence for a Close Companion?
Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel +1 more
We present new X-ray and radio observations of the Wolf-Rayet star EZ CMa (HD 50896) obtained with XMM-Newton and the Very Large Array (VLA). This WN4 star exhibits optical and UV variability at a period of 3.765 days whose cause is unknown. Binarity may be responsible, but the existence of a companion has not been proven. The radio spectral energ…
Infrared spectral classification of normal stars.
Heras, A. M.; Shipman, R. F.; Price, S. D. +8 more
Moderate resolution (~400) 2.38-45.2 mu m infrared spectra of stars without dust features were obtained with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). The observations are part of a larger program with the objective to extend and refine the current infrared classification schemes. In particular, our dat…
Broad-band continuum and line emission of the gamma-ray blazar PKS 0537-441
Maraschi, L.; Pian, E.; Falomo, R. +10 more
PKS 0537-441, a bright gamma -ray emitting blazar, was observed at radio, optical, UV and X-ray frequencies during various EGRET pointings, often quasi-simultaneously. In 1995 the object was found in an intense emission state at all wavelengths. BeppoSAX observations made in 1998, non-simultaneously with exposures at other frequencies, allow us to…
Chandra LETGS observation of the active binary Algol
Schmitt, J. H. M. M.; Burwitz, V.; Mewe, R. +2 more
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 temperatures up to T~ 15-20 MK from the continuum and from ratios of hydrogen-like and helium-like ions of Si, Mg, and Ne. In addition lower temperature material is pres…
Detection of HD in emission towards Sagittarius B2
Ceccarelli, C.; Caux, E.; Swinyard, B. M. +2 more
The giant molecular cloud Sagittarius B2, located near the Galactic Centre, has been observed in the far-infrared by the ISO Long Wavelength Spectrometer. Wavelengths in the range 47-196 mu m were covered with the high resolution Fabry-Pérot spectrometer, giving a spectral resolution of 30-40 km s-1. The J=1->0 and J=2->1 rotation…
Signatures of wave-ion interactions in the solar wind: Ulysses observations
Goldstein, Bruce E.; Neugebauer, Marcia; Gary, S. Peter
Theory and simulations predict that resonant wave-particle scattering by enhanced magnetic fluctuations yields characteristic signatures in properties of solar wind ions. Here Ulysses/Solar Wind Observations Over the Poles of the Sun (SWOOPS) instrument measurements of protons and alpha particles are examined to seek three types of these signature…
Coronal Loop Heating by Random Energy Releases
Erdélyi, Robert; Mendoza-Briceño, César A.; Di G. Sigalotti, Leonardo
It was suggested by Parker that the solar corona is heated by numerous small localized events called nanoflares. High-resolution satellites (the Solar and Heliospheric Observatory and Transition Region and Coronal Explorer [TRACE]) have shown a kind of very small scale activity at transition region temperatures (i.e., explosive events, microflares…
Optical and Near-Infrared Photometry of Distant Galaxy Clusters
Dickinson, Mark; Eisenhardt, Peter R.; Stanford, S. A. +2 more
We present optical and near-infrared photometry of 45 clusters of galaxies at 0.1<z<1.3. Galaxy catalogs in each cluster were defined at the longest wavelength available, generally the K band, down to approximately 2 mag below M*. We include finding chart images of the band used for catalog definition. The photometry has been used…
Spectroscopic Determination of Stellar Atmospheric Parameters: Application to Mid-F through Early-K Dwarfs and Subgiants
Sato, Bun'ei; Kambe, Eiji; Takeda, Yoichi +2 more
Takeda et al.'s (2002, PASJ, 54, 451) method for the spectroscopic determination of stellar atmospheric parameters (Teff, logg, vt, and [Fe/H]) from the equivalent widths of Fe I and Fe II lines was applied to 32 dwarfs/subgiants of mid-F through early-K types based on high-quality echelle spectra obtained at Okayama Astrophy…