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Structure and dynamics of an active region loop system observed on the solar disc with SUMER on SOHO
Marsch, E.; Lanzafame, A. C.; Brooks, D. H. +3 more
In this paper we present and discuss spectra obtained by SUMER on SOHO from an active region loop system observed on the solar disc, close to the central meridian, on July 26th, 1996. The region was observed with a spatial resolution of about 2arcsec by 2arcsec in emission lines forming in the transition region and inner corona, with the aim of in…
Giant macro-spicule as observed by CDS on SOHO
Doyle, J. G.; Banerjee, D.; O'Shea, E.
We examine spectral time series of coronal line Mg ix 368 Ä and transition region line O v 629 Ä, observed with the Coronal Diagnostic Spectrometer (CDS) onboard the SOHO spacecraft. Primarily we were looking for intensity and velocity oscillations in polar plumes, however by chance we detected a giant macro-spicule at the limb and were able to fo…
Multi-wavelength bispectrum speckle interferometry of R Cas and comparison of the observations with Mira star models
Weigelt, G.; Hofmann, K. -H.; Balega, Y. +1 more
We present diffraction-limited (30 mas) bispectrum speckle interferometry observations of the Mira star R Cas with the Russian 6 m SAO telescope. The speckle interferograms were recorded through narrow-band interference filters with centre wavelength/bandwidth of 671 nm/6 nm and 714 nm/6 nm (strong TiO absorption band), 700 nm/6 nm (moderate TiO a…
Follow-up photometry of six new beta Cephei stars discovered from the HIPPARCOS mission
Aerts, C.
We present ground-based follow-up photometry in the Geneva seven-colour photometric system of six new candidate beta Cep stars. The variability of these objects was originally found from the HIPPARCOS mission. From the new data we are able to confirm their beta Cep-type nature, to detect the pulsational frequencies and to identify most of the degr…
Structure and evolution of low-mass Population II stars
D'Antona, F.; Montalbán, J.; Mazzitelli, I.
The focus of the present paper is on the detailed description of the internal structures of low mass, population II stars, to clarify some issues about these stellar models and, mainly, their present reliability for observational comparisons. We then explore 1) the role of the local convective model; 2) the differences between "grey" and "non grey…
Far-infrared photometry and mapping of Herbig Ae/Be stars with ISO
Burkert, A.; Ábrahám, P.; Henning, Th. +2 more
Seven Herbig Ae/Be stars were observed at mid- and far-infrared wavelengths with ISOPHOT, the photometer on-board the Infrared Space Observatory. At λ{<=}25µm, where the emission mainly arises from a compact circumstellar region, the observed spectral energy distributions can be described by power-law relationships between wavelength and …
A young stellar group associated with HD 199143 (d=48 pc)
McCollum, B.; de Winter, D.; van den Ancker, M. E. +1 more
We present new optical and ultraviolet spectroscopy of the anomalous EUV emitter HD 199143 (F8V). High resolution spectra in the Halpha and Na I D wavelength regions show evidence for very rapid (a few hundred km/s) rotation of the stellar photosphere. Using archive IRAS data we also show that the star has excess emission above photospheric levels…
ISOPHOT Serendipity Survey observations of interstellar clouds I. Detection of the Coldest Cores in Chamaeleon
Krause, O.; Lemke, D.; Laureijs, R. J. +5 more
ISOPHOT Serendipity Survey (ISOSS) observations at 170 \um\ reveal cold dust clouds in the nearby star forming region Chamaeleon. The distribution of the ISOSS/IRAS based T(I170/I100) colour temperature have been studied in a nearby low-mass star forming region. T(I170/I100) separates the obscured and in…
Infrared, radio and optical variability of the BL Lacertae object 2007+777
Quirrenbach, A.; Wagner, S. J.; Zensus, J. A. +8 more
We present infrared observations at wavelengths of 60 and 100 mu m and contemporaneous radio (five frequencies) and optical (R band) monitoring of the BL Lac object 2007+777. During a three-week campaign with the ISO, the VLA, the Effelsberg 100 m radio telescope, and optical telescopes in Heidelberg and on Calar Alto, Spain, we observed variabili…
A detailed spectroscopic analysis of varepsilon Per. I. Determination of the orbital parameters and of the frequencies
Mathias, P.; Aerts, C.; De Cat, P. +1 more
We present the analysis of 445 high signal-to-noise spectra of the Si III triplet at 4553 Ä, 4568 Ä, 4575 Ä of the line-profile variable star varepsilon Persei. The data were gathered during 14 consecutive nights and fully cover the orbital cycle of the binary. The orbital parameters that we derive from our data for the close binary are in full ag…