Search Publications
A puzzling periodicity in the pulsating DA white dwarf G 117-B15A
Clemens, J. C.; van Kerkwijk, M. H.; Kotak, R.
We present time-resolved optical spectrophotometry of the pulsating hydrogen atmosphere (DA) white dwarf G 117-B15A. We find three periodicities in the pulsation spectrum (215 s, 272 s, and 304 s) all of which have been found in earlier studies. By comparing the fractional wavelength dependence of the pulsation amplitudes (chromatic amplitudes) wi…
Comprehensive modelling of the planetary nebula LMC-SMP 61 and its [WC]-type central star
Hamann, W. -R.; Koesterke, L.; Szczerba, R. +3 more
We present a comprehensive study of the Magellanic Cloud planetary nebula SMP 61 and of its nucleus, a Wolf-Rayet type star classified [WC 5-6]. The observational material consists of HST STIS spectroscopy and imaging, together with optical and UV spectroscopic data collected from the literature and infrared fluxes measured by IRAS. We have perfor…
Gas near active galactic nuclei: A search for the 4.7 µm CO band
Lutz, D.; Genzel, R.; Sturm, E. +2 more
In order to constrain the properties of dense and warm gas around active galactic nuclei, we have searched Infrared Space Observatory spectra of local active galactic nuclei (AGN) for the signature of the 4.7 µm fundamental ro-vibrational band of carbon monoxide. Low resolution spectra of 31 AGN put upper limits on the presence of wide absor…
Abundances in planetary nebulae: Me 2-1
Pottasch, S. R.; García-Lario, P.; Surendiranath, R.
ISO and IUE spectra of the round planetary nebula
A high resolution spectroscopic study of the extraordinary planetary nebula LMC-N66
Hamann, W. -R.; Ruiz, M. T.; Peña, M. +2 more
The planetary nebula N66 in the Large Magellanic Cloud is an extraordinary object, as it is the only confirmed PN where the central star is a Wolf-Rayet star of the nitrogen sequence, i.e. of type [WN]. Moreover, the star showed a dramatic brightness outburst in 1993-1994. In a previous paper (Hamann et al. \cite{Hamann03}) we analyzed the changin…
Dust production and coma morphology of 67P/Churyumov-Gerasimenko during the 2002/2003 apparition. II. A comparative study of dust production in 46P/Wirtanen and 67P/Churyumov-Gerasimenko during their 2002/2003 apparition
Kidger, M. R.
A comparison is made of the light curves and and dust production of the initial target for the ROSETTA mission, 46P/Wirtanen and the new target 67P/Churyumov-Gerasimenko during their recent 2002/2003 apparition. The study is based on amateur CCD monitoring using a standardised method to produce consistent photometry in Johnson-Kron-Cousins system.…
Search for 1-10 Hz modulations in coronal emission with SECIS during the August 11, 1999 eclipse
Keenan, F. P.; Phillips, K. J. H.; Williams, D. R. +3 more
Results of the search of the periodic changes of the 530.3 nm line intensity emitted by selected structures of the solar corona in the frequency range 1-10 Hz are presented. A set of 12 728 images of the section of the solar corona extending from near the north pole to the south-west were taken simultaneously in the 530.3 nm (``green'') line and w…
The phase curve of cometary dust: Observations of comet 96P/Machholz 1 at large phase angle with the SOHO LASCO C3 coronagraph
Schwenn, R.; Jockers, K.; Grynko, Ye.
We have analyzed brightness and polarization data of comet 96P/Machholz, obtained with the SOHO-LASCO C3 coronagraph at phase angles up to 167° and 157°, respectively. The polarization data are characteristic of a typical dusty comet. Within error limits the corresponding trigonometric fit describes the new data measured at l…
CDS wide slit time-series of EUV coronal bright points
Foley, C. R.; Doyle, J. G.; Nakariakov, V. M. +1 more
Wide slit (90''×240'') movies of four Extreme Ultraviolet coronal bright points (BPs) obtained with the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SoHO) have been inspected. The wavelet analysis of the He I 584.34 Å, O V 629.73 Å and Mg VII/IX 368 Å time-series confirms the oscillat…
GIRAFFE multiple integral field units at VLT: A unique tool to recover velocity fields of distant galaxies
Flores, H.; Hammer, F.; Puech, M. +2 more
The GIRAFFE spectrograph is unique in providing the integral field spectroscopy of fifteen distant galaxies at the same time. It has been successfully implemented at the second VLT unit within the FLAMES facility. We present GIRAFFE observations acquired during the Guaranteed Time Observation of the Paris Observatory, using total exposure times ra…