Search Publications
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…
Masses and Other Parameters of the Post-Common Envelope Binary BE Ursae Majoris
Napiwotzki, Ralf; Liebert, James; Ferguson, Donald H. +2 more
The binary star BE Ursae Majoris is recently emerged from the common envelope phase; indeed, the hot sdO/DAO component is the central star of the associated planetary nebula. As such, BE UMa represents an important test case of stellar evolution theory. Using the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph (GHRS), we measured…
Do EUV Nanoflares Account for Coronal Heating?
Aschwanden, Markus J.
Recent observations with EUV imaging instruments such as SOHO/EIT and TRACE have shown evidence for flare-like processes at the bottom end of the energy scale, in the range of Eth≈1024-1027 erg. Here we compare these EUV nanoflares with soft X-ray microflares and hard X-ray flares across the entire energy range. Fr…
Energy spectra of 50-keV to 20-MeV protons accelerated at corotating interaction regions at Ulysses
Simnett, G. M.; Lario, D.; Balogh, A. +6 more
We analyze here the energy spectra of 50-keV to 20-MeV protons accelerated at corotating shocks observed at Ulysses in the southern heliosphere during 1992 and 1993. In general, our results are inconsistent with the predictions of two models based on diffusive shock acceleration theory (Fisk and Lee [1980] and Jones and Ellison [1991]). The main r…
Dust in Spiral Galaxies: Comparing Emission and Absorption to Constrain Small-Scale and Very Cold Structures
Ryder, Stuart D.; White, Raymond E., III; Keel, William C. +1 more
The detailed distribution of dust in the disks of spiral galaxies is important to understanding the radiative transfer within disks and to measuring overall dust masses if significant quantities of dust are either very opaque or very cold. We address this issue by comparing measures of dust absorption, using the galaxy-overlap technique in the opt…
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 …
A Multifrequency Catalog of LINERs
Masegosa, J.; Dultzin-Hacyan, D.; Carrillo, R. +1 more
CIR Associated Energetic Particles in the Inner and Middle Heliosphere
Mason, G. M.; Sanderson, T. R.
Energetic particles associated with Corotating Interaction Regions (CIRs) are observed throughout the inner and middle heliosphere, showing large positive (>100%/AU) radial intensity gradients. Their appearance at 1 AU is associated with the appearance of fast, recurrent solar wind streams. At several AU, CIR energetic particles are accelerated…
HUBBLE SPACE TELESCOPE Snapshot Survey of 3CR Quasars: The Data
Baum, Stefi A.; McCarthy, Patrick J.; Lehnert, Matthew D. +6 more
We present images taken with the Wide Field Planetary Camera (WFPC-2) on the Hubble Space Telescope (HST) of 43 quasars selected from the 3CR radio catalog. The redshift range of the targets is large--0.3<~z<~2--and allows us to probe the nature of quasar hosts from about 20% to 80% of the age of the universe. These data were taken in the co…