Search Publications
The Hubble Deep Field North reveals a supernova at z~0.95
Mannucci, F.; Ferrara, A.
We report the discovery of a variable object in the Hubble Deep Field North (HDF-N) which brightened, during the 8.5d sampled by the data, by more than 0.9mag in I_814 and about 0.7mag in V_606, remaining stable in B_450. Subsequent observations of the HDF-N show that two years later this object has dimmed to about its original brightness in I_814…
Electron densities above a polar coronal hole based on improved Si IX density diagnostics
Doyle, J. G.; Fludra, A.; Keenan, F. P. +2 more
Using new close-coupling excitation rates for the C-like ion Si ix, density-diagnostic ratios based on Si ix lines have been re-evaluated and applied to a sequence of CDS observations taken above a polar coronal hole. The derived electron densities are in excellent agreement with previous values of Neestimated from the N-like ion Si vii…
An astrometric catalogue for the area of Coma Berenices
Abad, C.; Vicente, B.
A catalogue of stellar positions and proper motions down to the 14th photographic magnitude in the area of the open cluster in Coma Berenices is compiled from data of 12 different sources. The accuracy of the proper motion data is comparable to that of the Hipparcos Catalogue. The catalogue Table 5 is only available in electronic form at the CDS v…
Intereclipse Spectroscopic Snapshot of epsilon Aurigae with the Hubble Space Telescope
Lambert, David L.; Sheffer, Yaron
A single-epoch low-resolution Goddard High Resolution Spectrograph spectrum of the eclipsing binary epsilon Aurigae was obtained while the secondary was orbiting toward eclipse by the primary. The spectrum as recorded between 1175 and 1461 Å is rich with emission and absorption lines which include stellar and interstellar components. The emission-…
Distances to the High Galactic Latitude Molecular Clouds G192-67 and MBM 23-24
Burrows, David N.; Grant, Catherine E.
We report on distance determinations for two high-Galactic latitude cloud complexes, G192-67 and MBM 23-24. No distance determination exists in the literature for either cloud. Thirty-four early-type stars were observed toward the two clouds, more than half of which have parallaxes measured by the Hipparcos satellite. For the remaining stars, we h…
Concurrent solar and corotating interaction region particle events in August 1996
Torsti, J.; Anttila, A.; Sahla, T.
The energetic particle telescope ERNE onboard SOHO registered a continuous particle flux enhancement during August 7-18, 1996. The particle event was limited in the low energy range from 1.6 to 8 MeV during the first week of the event. It originated from a corotating interaction region (CIR). At 1630 UT on August 13, an additional new flux of ener…
An Analytic Description of Coronal Proton Trapping
Kocharov, Leon; Torsti, Jarmo; Kovaltsov, Gennadi A.
Analytic steady state solutions of the focused diffusion equation are used to deduce proton trapping time, τtrap, an average residence time for all particles injected into the magnetic loop. We take into account the effect of magnetohydrodynamic (MHD) turbulence and the divergence of magnetic field lines in both the corona and chromosph…
Compact Nuclei in Galaxies at Moderate Redshift. II. Their Nature and Implications for the Active Galactic Nucleus Luminosity Function
Green, Richard F.; Griffiths, Richard E.; Ratnatunga, Kavan +1 more
This study explores the space density and properties of active galaxies to z~=0.8. We have investigated the frequency and nature of unresolved nuclei in galaxies at moderate redshift as indicators of nuclear activity such as active galactic nuclei (AGNs) or starbursts. Candidates are selected by fitting imaged galaxies with multicomponent models u…
Spectrophotometry of Saturn's small satellites and rings from Hubble Space Telescope images
Sicardy, Bruno; Poulet, François; Karoschka, Erich
We investigate the photometric properties of four of Saturn's inner satellites (Prometheus, Pandora, Janus, and Epimetheus) and five ring regions (the A, B, and C rings; the Cassini division; and the F ring). We have used Hubble Space Telescope images taken in July 1991 and during the Saturn's ring plane crossings by the Earth (August 1995) and th…
ET And, HD 219891, or HD 219668 - which one shows short-term variability?
Lehmann, H.; Scholz, G.; Hildebrandt, G. +1 more
The result of recent photometric observations of the CP star ET And, published by Weiss et al. (1998), shows that the known brightness variation of about 145 min has to be obviously assigned to the comparison star HD 219891. In order to test this statement we investigate the Hipparcos photometry of ET And, HD 219891 and the check star, HD 219668, …