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Characteristics of quiet Sun cell and network brightenings
Phillips, K. J. H.; Harra, L. K.; Gallagher, P. T.
Extreme ultraviolet observations of the quiet Sun are made with the Coronal Diagnostic Spectrometer (cds) on board the Solar and Heliospheric Observatory (soho). It has been previously noted that frequent transition region brightenings occur in both the bright network and dark cell regions. Analysing 1125 events, we determined the characteristics …
ISO observations of a sample of 60 mu m peaker galaxies
Hanlon, L.; McBreen, B.; Clavel, J. +9 more
The sample of IRAS galaxies with spectral energy distributions that peak near 60 mu m are called Sixty Micron Peakers (SMPs or 60PKs). Their generally peculiar and amorphous morphologies, hot dust and lack of a cirrus component have been interpreted as being indicative of a recent interaction/merger event. Mid-infrared spectra of eight SMPs, obtai…
Polaris: astrometric orbit, position, and proper motion
Wielen, R.; Dettbarn, C.; Jahreiß, H. +2 more
We derive the astrometric orbit of the photo- center of the close pair α UMi AP (= α UMi Aa) of the Polaris multiple stellar system. The orbit is based on the spectroscopic orbit of the Cepheid α UMi A (orbital period of AP: 29.59 years), and on the difference Δµ between the quasi-instantaneously measured HIPPARCOS proper motion of Polaris a…
HV Ursae Majoris, a new contact binary with early-type components
Kiss, L. L.; Alfaro, E. J.; Csák, B. +1 more
We present the first UBV and uvby photometric observations for the short period variable star HV Ursae Majoris classified as a field RRc variable. The observed differences between the consecutive minima and the lack of colour variations disagree with the RRc-classification and suggest the possible binary nature of HV UMa. In order to reveal the re…
Multi-wavelength observations and modelling of shock-cloud interaction regions in the Vela Supernova Remnant
Bocchino, F.; Sciortino, S.; Raymond, J. +1 more
We present optical photometric and spectrophotometric observations of two selected filaments near the North rim of the Vela supernova remnant also observed in UV with the International Ultraviolet Explorer, and in X-rays with the ROSAT PSPC detector. From the optical data, we have derived spatially-resolved ( ~ 3'') profiles of several …
VLBI observations of two single dMe stars: spatial resolution and astrometry
Güdel, M.; Benz, A. O.; Conway, J. E. +1 more
We report on 3.6 cm VLA and VLBA observations of
HST spectroscopy of the double QSO HS 1216+5032 AB
Reimers, D.; Hagen, H. -J.; Lopez, S.
We report on Hubble Space Telescope Faint Object Spectrograph observations of the double QSO HS 1216+5032 AB (z_e(A)=1.455; z_e(B)=1.451, and angular separation theta =9.1farcs ). The spectral coverage is 910 Å to 1340 Å in the QSO rest-frame. An unusual broad-absorption-line (BAL) system is observed only in the B component: maximum outflow veloci…
Statistics of Hipparcos binaries: probing the 1-10 AU separation range
Lindegren, L.; Quist, C. F.
The observation of double stars by Hipparcos is modelled in order to check the statistics of double-star solutions in the Hipparcos Catalogue and to set quantitative limits on binary distributions. A Galaxy model is combined with models of binary distributions and of the observation process to derive the expected numbers of the different kinds of …
New astrometric binaries among HIPPARCOS stars
Gontcharov, G. A.; Andronova, A. A.; Titov, O. A.
A new realization of the International Celestial Reference System (ICRS) is built upon the data of the HIPPARCOS catalogue and astrometric ground-based catalogues of the 20th century reduced to the HIPPARCOS system. Non-linear motion of some stars has been detected with this realization of the ICRS. This motion is separated into the pro…
Search for an exosphere around 51 Pegasi B with ISO
Rauer, H.; Schneider, J.; Bockelée-Morvan, D. +2 more
The detection of absorption features in spectra of 51 Peg obtained during transit of its planet would provide a first clue on the physical nature of the planet. We have searched for signatures of an exosphere of the planet orbiting 51 Peg in the wavelength range from 2.39 µm to 3.5 µm and from 4.55 µm to 4.74 µm using SWS o…