Search Publications
Inferences on the solar envelope with high-degree modes
Christensen-Dalsgaard, J.; Rabello-Soares, M. C.; Basu, S. +1 more
We investigate the structure of the Sun by helioseismic inversion of a set of p-mode frequencies which includes new precise observations of modes with high degree (l < 1000) obtained from the MDI instrument on the SOHO satellite (Rhodes et al. \cite{rh98}). Such data have the potential to improve the resolution of the solar structure in the nea…
Calibration of the distance scale from galactic Cepheids. II. Use of the HIPPARCOS calibration
Musella, I.; Paturel, G.; Theureau, G. +3 more
New estimates of the distances of 36 nearby galaxies is presented. These are based on the calibration of the V- and I-band Period-Luminosity relations for galactic Cepheids measured by the HIPPARCOS mission. The distance moduli are obtained in a classical way. The statistical bias due to the incompleteness of the sample is corrected according to t…
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…
Spectral Energy Distributions of starburst galaxies in the 900-1200 Å range
Buat, V.; Burgarella, D.; Kunth, D. +1 more
We present the 970-1175 Å spectral energy distributions (SEDs) of 12 starburst galaxies observed with the Far Ultraviolet Spectroscopic Explorer FUSE. We benefit from the high spectral resolution of FUSE to estimate a continuum as much as possible unaffected by the interstellar lines. The continuum is rather flat with, in a few cases, a decrease a…
Classical novae in outburst: The early evolution of the ultraviolet continuum
Altamore, A.; González-Riestra, R.; Cassatella, A.
In the framework of a phenomenological study of the ultraviolet properties of classical novae in outburst, we have selected 12 objects among the best monitored at low resolution with the IUE satellite, and studied the temporal evolution of the ultraviolet continuum and of the O I 1300 Å line flux during the early post-outburst phase. We confirm th…
Transition region explosive events: Do they have a coronal counterpart?
Doyle, J. G.; Madjarska, M. S.; Teriaca, L.
EUV explosive events are a prominent class of phenomena characterizing the solar transition region. Their correct location in the wider frame-work of the outer solar atmosphere can provide important insight on the nature of the transition region itself and its relationship with the hotter corona and the cooler chromosphere. In this paper we presen…
An evaluation of the correlation between open solar flux and total solar irradiance
Lockwood, M.
The correlation between the coronal source flux FS and the total solar irradiance ITS is re-evaluated in the light of an additional 5 years' data from the rising phase of solar cycle 23 and also by using cosmic ray fluxes detected at Earth. Tests on monthly averages show that the correlation with FS deduced from th…