Search Publications
Opacity in the upper atmospheres of active stars. II. AD Leonis
Christian, D. J.; Mathioudakis, M.; Bloomfield, D. S. +4 more
We present FUV and UV spectroscopic observations of AD Leonis, with the aim of investigating opacity effects in the transition regions of late-type stars. The C III lines in FUSE spectra show significant opacity during both the quiescent and flaring states of AD Leonis, with up to 30% of the expected flux being lost during the latter. Other FUSE e…
The proper motion of the isolated neutron star RX J1605.3+3249
de Luca, A.; Mignani, R. P.; Zane, S. +1 more
Aims.We present a new optical observation of the X-ray dim isolated neutron star RX J1605.3+3249, performed in 2005 with the Wide Field Channel (WFC) of the Advanced Camera for Surveys (ACS) on board Hubble Space Telescope, aimed at measuring the neutron star proper motion.
Methods: .We have compared the target position with the one measured i…
Study of whistler mode instability in Saturn's magnetosphere
Singhal, R. P.; Tripathi, A. K.
A dispersion relation for parallel propagating whistler mode waves has been applied to the magnetosphere of Saturn and comparisons have been made with the observations made by Voyager and Cassini. The effect of hot (suprathermal) electron-density, temperature, temperature anisotropy, and the spectral index parameter, κ, on the temporal growth rate…
Whistler-mode auroral hiss emissions observed near Saturn's B ring
Gurnett, D. A.; Hospodarsky, G. B.; Kurth, W. S. +2 more
An unusual whistler-mode emission, similar to terrestrial auroral hiss, was observed by the radio and plasma wave instrument on the Cassini spacecraft during the 1 July 2004 pass over the rings of Saturn. By using an electron density model that is consistent with measurements of the local electron plasma frequency, ray-tracing calculations have be…
X-Ray Observations of SN 1006 with INTEGRAL
Rho, J.; Lund, N.; Boggs, S. E. +4 more
The remnant of the supernova of 1006 AD, the remnant first showing evidence for the presence of X-ray synchrotron emission from shock-accelerated electrons, was observed for ~1000 ks with INTEGRAL in order to study electron acceleration to very high energies. The aim of the observation was to characterize the synchrotron emission and attempt to de…
Hubble Space Telescope observations of SV Cam - I. The importance of unresolved star-spot distributions in light-curve fitting
Donati, J. -F.; Jeffers, S. V.; Collier Cameron, A. +1 more
We have used maximum entropy eclipse-mapping to recover images of the visual surface brightness distribution of the primary component of the RS CVn eclipsing binary SV Cam, using high-precision photometry data obtained during three primary eclipses with Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope (HST). These were augmen…
Challenging the identification of nitride dust in extreme carbon star spectra
Speck, A. K.; Pitman, K. M.; Hofmeister, A. M.
Nitride dust is predicted to form in small amounts around carbon stars, but the most likely candidate species such as aluminium nitride (AlN) have not yet been detected. Recently, α-Si3N4 was inferred to be the main carrier of the 8.5-12.5 µm absorption band(s) of an extreme carbon star (AFGL 5625), based on comparison …
A Far-Ultraviolet Study of the Hot White Dwarf in the Dwarf Nova WW Ceti
Szkody, Paula; Sion, Edward M.; Godon, Patrick +1 more
We present a synthetic spectral analysis of IUE archival and FUSE (Far Ultraviolet Spectroscopic Explorer) far-UV spectra of the peculiar dwarf nova WW Cet. During the quiescence of WW Cet, a white dwarf with Twd~26,000+/-1000 K can account for the far-UV flux and yields the proper distance. However, the best agreement with the observat…
Internal structure of Rhea
Castillo-Rogez, Julie
We model the interior of Rhea on the basis of observational constraints and the results from geodynamical models available in the literature. Ten main types of models are defined, depending on the presence or absence of a high-pressure ice layer (ice II), and the extent of separation of the rock component from the volatiles. The degree-two gravity…
Solar and Heliospheric Observatory/Large Angle Spectrometric Coronagraph Polarimetric Calibration
Davila, Joseph M.; Wang, Dennis; Moran, Thomas G. +2 more
We present a polarimetric characterization and correction for the Solar and Heliospheric Observatory/Large Angle Spectrometric Coronagraph (SOHO/LASCO) C2 and C3 white light coronagraphs. By measuring the uncorrected polarization angles in solar minimum C2 coronal images, we have determined that the coronagraph acts as an optical phase retarder wh…