Search Publications
Microflaring of a solar bright point
Curdt, W.; Huovelin, J.; Vilhu, O. +2 more
A 50 x 50 arcsec region near the solar disc center containing a bright point (BP) was observed with the SUMER- spectrograph of the SOHO observatory. The data consist of two hours observation of four far-UV emission lines formed between 2 x 104-6x 105 K, with 2 arcsec spatial, 2.8 min temporal and 4 km s-1 spectral …
Observing programs of the Kyiv meridian axial circle equipped with a CCD micrometer
Andruk, V.; Babenko, Yu.; Lazorenko, P. +6 more
The present status of the Kyiv meridian axial circle after its refurbishment is described. The mounting of a new micrometer with the front-illuminated CCD 1040x1160 allows to observe stars up to V=16 mag. For the stars of 11-14 mag, the internal positional accuracy of a single observation is 0.05-0.10'', and stellar V values are determined with an…
ISOPHOT far-infrared photometry of NGC 3079
Walker, H. J.; Klaas, U.
FIR photometry (from 15 mu m to 200 mu m) of NGC 3079 which is resolved by ISOPHOT at 60 mu m is presented. With the assumption of an unresolved core plus an extended disk component, good consistency with IRAS and SCUBA data is found. The SED of the total flux between 60 mu m and the submm can be modelled by the superposition of three dust compone…
UV line intensity and flow velocity distributions in two coronal mass ejections as deduced by UVCS-SOHO observations
Uzzo, M.; Spadaro, D.; Ventura, R. +1 more
The Ultraviolet Coronagraph Spectrometer (UVCS) instrument onboard the SOHO satellite observed two coronal mass ejections on November 2 and 3, 2000, related to the eruptions of a large filament structure in an active region close to the West limb of the Sun, and of a prominence near the South Pole, respectively. Intensity and profile of the O VI r…
Analysis of archival EXOSAT data on the X-ray burst source Serpens X-1
Min, K. W.; Seon, K. -I.
We present analysis of data obtained from the Medium Energy proportional counter array (ME) from the EXOSAT observations of the X-ray burst source Ser X-1 made in 1983 and 1985. From the combined analysis of the spectral and fast variability properties, we show that the source is an atoll source in the banana state during the observations. The per…
The origin of the radio emission from beta Lyrae
Umana, G.; Leone, F.; Trigilio, C.
In this paper we present new observational evidence that supports the presence of an extra source of continuum emission in the binary system
Systematic relations between the HIPPARCOS catalogue and major (fundamental) catalogues of the 20th century (Paper II)
Schwan, H.
Presented are the systematic relations between the HIPPARCOS catalogue and major catalogues of the 20th century, not yet treated in Paper I. Colour-dependent errors in the catalogues are also determined and eliminated. The derived systematic relations allow one to reduce observations given in the system of one of the analyzed catalogues to the HIP…
Helioseismic limit on heavy element abundance
Antia, H. M.; Chitre, S. M.
Primary inversions of accurately measured solar oscillation frequencies coupled with the equations of thermal equilibrium and other input physics, enable us to infer the temperature and hydrogen abundance profiles inside the Sun. These profiles also help in setting constraints on the input physics as well as on heavy element abundance in the solar…
Quiet-Sun variability observed with SUMER and CDS
Solanki, S. K.; Brković, A.; Rüedi, I.
Brightness variations of solar features are investigated using time series of images and spectra of quiet-Sun regions at disc centre obtained with the Coronal Diagnostic Spectrometer (CDS) and the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument onboard the SOHO spacecraft. Ultraviolet emission lines sampling temperatures of …
Detecting low amplitude periodicities with HIPPARCOS
Kallinger, T.; Weiss, W. W.
The HIPPARCOS and TYCHO catalogues have proven to be a very powerful source for detection of variability in stars. The photometric errors for individual measurements are typically of the order of a few millimagnitudes. Amplitudes for periodic variability of stars and based on HIPPARCOS data are published which are of the same order. An example cou…