Search Publications
Evolution of X-ray activity and rotation on G-K giants
Gondoin, P.
The recent availability of stellar parallaxes provided by the Hipparcos star catalogue (ESA 1997) enables an accurate determination of the positions of single field giants in a theoretical H-R diagram and a reliable estimate of their masses. The present study combines these new astrometric data with previously published X-ray fluxes and rotational…
A wavelet analysis of active region oscillations
Harrison, R. A.; Priest, E. R.; Ireland, J. +1 more
The wavelet transform is applied to the analysis of active region oscillations. The localised (in time) nature of the wavelet transform allows us to study both the duration of any statistically significant oscillations as well as their period. Time series arising from SOHO (Solar and Heliospheric Observatory) CDS-NIS (Coronal Diagnostic Spectromet…
How many lambda Bootis stars are binaries?
Bonifacio, Piercarlo; Faraggiana, Rosanna
In the attempt to shed new light on the lambda Boo phenomenon we analyzed the astrometric, photometric and spectroscopic characteristics of stars out of a list of recently selected lambda Boo candidates. We show that the class is still ill-defined and discuss the possibility that some, if not most stars presently classified as lambda Boo, are in f…
On the nature of the current GOLF p-mode signal
García, R. A.; Pallé, P. L.; Turck-Chièze, S. +9 more
The GOLF experiment on board SOHO is designed to measure global oscillations of the disk-integrated sunlight with high sensitivity and with long term stability. The GOLF data is thus ideally suited for both the study of the p-mode spectrum and to address the search for gravity modes. Due to their occasional malfunction the project decided to stop …
VLT and HST observations of a candidate high redshift elliptical galaxy in the Hubble Deep Field South
Dickinson, M.; Treu, T.; Rosati, P. +9 more
The combined use of the ESO Very Large Telescope (VLT) UT1 Science Verification (SV) images and of the Hubble Space Telescope (HST) Hubble Deep Field South observations allows us to strengthen the identification as a candidate elliptical galaxy of the Extremely Red Object HDFS 223251-603910 previously identified by us on the basis of NICMOS and Ce…
Explosive events in the solar atmosphere
Doyle, J. G.; Erdélyi, R.; Sarro, L. M. +1 more
Two examples of explosive events observed with SUMER in transition region spectral lines are reported here; one detected in C iv 1548 Angstroms, in a region within the northern polar coronal hole, and the other in O vi 1032 Angstroms, in an active region. The event measured in C iv lasted ~ 3 min and extended approximately a region of 8 arc sec al…
An HST surface photometric study of ultraluminous infrared galaxies
Mao, S.; Wu, H.; Zheng, Z. +3 more
We study the surface photometry for 13 single-nucleus ultraluminous IRAS galaxies (ULIRGs), selected from a parent sample of 58 galaxies obtained in a Hubble Space Telescope I-band snapshot survey. These galaxies can be classified into two classes using a quantitative chi (2) criterion based on whether their surface brightness profiles are well fi…
Hubble Space Telescope spectroscopy of hot helium-rich white dwarfs: metal abundances along the cooling sequence
Dreizler, S.
Metal abundances are the indicators of the chemical evolution in white dwarfs, which is dominated by the element separation due to the strong gravitational field. A reliable analysis and interpretation requires high resolution and high signal-to-noise UV spectroscopy. For hot helium rich DO white dwarfs this is currently only feasible with the Hub…
Circumstellar matter around M-giants in symbiotic binaries: SY MUSCAE and RW Hydrae
Schmutz, W.; Nussbaumer, H.; Schild, H. +1 more
For the eclipsing symbiotic binary system SY Mus we present evidence for an asymmetric density distribution around the M-giant. We obtain this result from an improved orbital solution. We determine a revised orbital period of P=625.0+/- 0.5 d from UV eclipse observations and a re-analysis of the visual light curve. Based on new radial velocity obs…
Spectroscopic, photometric, and polarimetric study of the Herbig AE candidate HD 36112
Miroshnichenko, A. S.; Savanov, I. S.; Pogodin, M. A. +6 more
We describe observations of the Herbig Ae candidate HD 36112 including high-resolution spectroscopy of photospheric and circumstellar lines, multi-colour photometry and polarimetry. These observations reveal that many features of the observational appearance of HD 36112 are similar to those of `classical' Herbig Ae stars. Among these are: the far …