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UV spectra of T Tauri stars from Hubble Space Telescope: RW Aur
Vittone, A. A.; Errico, L.; Lamzin, S. A.
Ultraviolet spectra of the classical T Tauri star RW Aur A observed with the Hubble Space Telescope were analysed. Absorption lines of neutral and singly ionized metals, blueshifted ~ 50 km s-1 relative to the star, were found. They originate in a dense (N>1010 cm-3) gas outflow, whose extension along the line o…
Chromospheric two-component NLTE modelling of the binary system V 711 Tau = HR 1099
Lanzafame, A. C.; Rodonò, M.; Busà, I.
In this paper we present the first two-component, semi-empirical chromospheric model of the RS CVn binary system V 711 Tau based on detailed fits of Hα and Mg II h line profiles. Synthetic Hα and Mg II h line profiles are computed by means of NLTE radiative transfer calculations. Using the observed Emission Measure distribution to constrain the tr…
FIP effect measurements in the off-limb corona observed by SUMER on SOHO
Dwivedi, B. N.; Mohan, A.; Landi, E.
Systematic differences between elemental abundances in the corona and in the photosphere have been long acknowledged in the Sun; these abundance anomalies are correlated with the first ionization potentials (FIPs) of the elements. This correlation is called FIP effect. Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitte…
A-shell stars in the Geneva system
Jaschek, C.; Hauck, B.
Among the various kinds of A stars having a peculiar spectrum, we find the A-shell stars. Many questions are still open concerning these stars, including their evolutionary status. In the present study we have used data from the Hipparcos catalogue to examine this point. We have found that the majority of A-shell stars are well above the main sequ…
The collision strength of the [Ne v] infrared fine-structure lines
Beintema, D. A.; Ferland, G. J.; van Hoof, P. A. M. +1 more
The calculation of accurate collision strengths for atomic transitions has been a long standing problem in quantitative spectroscopy. Most modern calculations are based on the R-matrix method and problems pertaining to the use of this method have led to a discussion of the accuracy of these results. More in particular, based on an analysis of the …
Star formation in distant starburst galaxies
Alloin, D.; Pastoriza, M. G.; Bonatto, C. +1 more
This paper discusses the stellar population content of distant (5 000 km s^{-1} <== V_R<=16 000 km s^{-1}) galaxies with enhanced star-formation activity. Distinction is made between isolated galaxies and galaxies morphologically disturbed, with clear signs of interaction such as mergers. In these galaxies the International Ultraviolet Explo…
Emerging flux as a driver for homologous flares
Culhane, J. L.; Harra, L. K.; Matthews, S. A. +1 more
We present multi-wavelength observations of 2 M-class solar flares observed by SoHO and Yohkoh, which appear to be homologous. By examination of the flare loop morphology and footpoints we propose a schematic reconnection scenario of a two loop interaction in a quadrupolar magnetic configuration, for both flares (Machado ?; Mandrini ?). After the …
Integral field spectroscopy of the radio galaxy 3C 171
Durret, F.; Petitjean, P.; Márquez, I. +1 more
We have performed integral field spectroscopy of the radio galaxy {3C 171} (redshift z=0.238) with the TIGER instrument at the Canada France Hawaii telescope in the Hβ -[OIII]4959-5007 wavelength region. We present the reconstructed Hβ and [OIII] images and compare them to the HST and radio maps. We discuss the variations of the [OIII]/Hβ line rat…
Rotational modulation and flares on RS CVn and BY Dra stars. XX. Photometry and spectroscopy of CC Eri in late 1989
Amado, P. J.; Doyle, J. G.; Mathioudakis, M. +4 more
The active flaring binary CC Eri was studied via multi-wavelength observations involving multi-based photometry and ground- and space-based spectroscopy. Combining early spectroscopic data with the present implies an orbital period of P=1.5615 days. Furthermore, the spectroscopic data suggests spectral types of K7 and M3 for the system. The optica…
Spiral and irregular galaxies in the Hubble Deep Field North. Comparison with early types and implications for the global SFR density
Rodighiero, G.; Franceschini, A.; Granato, G. L. +2 more
We analyze a morphologically-selected complete sample of 52 late-type (spiral and irregular) galaxies in the Hubble Deep Field North with total K-magnitudes brighter than K=20.47 and typical redshifts z ~ 0.5 to 1.4. This sample exploits in particular the ultimate imaging quality achieved by HST in this field, allowing us to clearly disentangle th…