Search Publications
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…
The multimode pulsation of the delta Scuti star V784 Cassiopeae
Thomson, J. R.; Derekas, A.; Garrido, R. +5 more
We present an analysis of new Johnson and Strömgren photometric and medium-resolution spectroscopic observations of the delta Scuti type variable star V784 Cassiopeae. The data were obtained in three consecutive years between 1999 and 2001. The period analysis of the light curve resulted in the detection of four frequencies ranging from 9.15 d
Timing analysis of the core of the Crab-like SNR G21.5-0.9
Mereghetti, S.; La Palombara, N.
The Crab-like SNR G21.5-0.9 was observed in the X-ray band (0.5-10 keV) by the XMM-Newton satellite for over 100 ks. The large effective area of the EPIC instrument has allowed us to perform a deep search for pulsations from the central core of . No pulsations were found with upper limits on the pulsed fraction between 7.5% and 40% (depending on f…
Quasi-molecular lines in Lyman wings of cool DA white dwarfs. Application to FUSE observations of G 231-40
Ferlet, R.; Lacour, S.; Vidal-Madjar, A. +3 more
We present new theoretical calculations of the total line profiles of Lyman alpha and Lyman beta which include perturbations by both neutral hydrogen and protons and all possible quasi-molecular states of H2 and H2+. They are used to improve theoretical modeling of synthetic spectra for cool DA white dwarfs. We com…
The spectroscopic binaries 21 Her and gamma Gem
Korotin, S. A.; Andrievsky, S. M.; Lehmann, H. +5 more
In the framework of a search campaign for short-term oscillations of early-type stars we analysed recently obtained spectroscopic and photometric observations of the early A-type spectroscopic binaries 21 Her and gamma Gem. From the radial velocities of 21 Her we derived an improved orbital period and a distinctly smaller eccentricity in compariso…