Search Publications
A Search for Lyα Emission from the Astrosphere of 40 Eridani A
Zank, Gary P.; Wood, Brian E.; Linsky, Jeffrey L. +1 more
We report the results of Hubble Space Telescope (HST) observations of the nearby (d=5.0 pc) K1 V star 40 Eri A, which we use to search for scattered Lyα emission surrounding the star indicative of the interaction between the stellar wind and the interstellar medium (ISM). Absorption from circumstellar hot H I has previously been detected around ma…
Cassini-VIMS at Jupiter: solar occultation measurements using Io
Sotin, C.; Brown, R. H.; Baines, K. H. +24 more
We report unusual and somewhat unexpected observations of the jovian satellite Io, showing strong methane absorption bands. These observations were made by the Cassini VIMS experiment during the Jupiter flyby of December/January 2000/2001. The explanation is straightforward: Entering or exiting from Jupiter's shadow during an eclipse, Io is illumi…
Modelling the Torques Affecting the Hipparcos Satellite
van Leeuwen, Floor; Fantino, Elena
Reconstructed attitude data for the Hipparcos mission as obtained in the final stages of the data analysis for the published catalogue is used to derive detailed information on the dynamics of the satellite. Most elements of the inertia tensor of the satellite could be calibrated from the observed acceleration data, which are also used to reconstr…
Relationship between decrease of net magnetic flux and solar major events
Liu, Y.; Tian, L. R.
Using the full disk magnetograms taken by SOHO/MDI, we studied the evolution of magnetic fluxes in the line-of-sight for twelve solar active regions in the 23rd cycle, which produced strong solar activities. It is measured that the fluxes of these regions were appreciably imbalanced when they moved past the central meridian, where reliable measure…
The obscured QSO 1SAX J1218.9+2958
Page, M. J.; Ramsay, G.; Loaring, N. S.
We present results from XMM-Newton observations of the obscured quasi-stellar object 1SAX J1218.9+2958. We find that the previously reported optical and soft X-ray counterpart positions are incorrect. However, we confirm the spectroscopic redshift of 0.176. The optical counterpart has a K magnitude of 13.5 and an R-K colour of 5.0 and is therefore…
The analogy between sunquakes and water waves
Podesta, J. J.
To investigate the seismic waves generated at the surface of the convection zone by a sunquake, the solar convection zone is modeled as an incompressible fluid layer of finite depth which is excited by a pressure pulse just above the solar surface. Solutions for the surface displacement ζ as a function of time are obtained by solving the linearize…
Anomalously bright UV lines of Fe II as a probe of gas condensations in the vicinity of hot stars
Johansson, S.; Letokhov, V. S.
Two UV lines of Fe II at 2507/2509 Å are extremely bright in spatially resolved HST/STIS spectra of dense gas condensations (the so called Weigelt blobs) close to the central star of η Carinae. The lines also appear unresolved in HST/FOS spectra of the star AE And. Under normal conditions the lines should hardly be observable. Based on recent stud…
High-Energy 3He-Rich Solar Particle Events
Kocharov, Leon; Torsti, Jarmo; Thompson, Barbara J. +2 more
Energetic particle observations of the ERNE instrument on board SOHO enable measurements of 3He and 4He fluxes beyond 15 MeV nucleon−1 with good statistical resolution. We report results of a survey of the ERNE observations covering the period from 8 February 1999 to 6 December 2000. We find 10 and 5 days during wh…
The Sun's Distance from the Galactic Plane
Branham, R. L., Jr.
Use is made of 93,106 parallaxes from the Hipparcos catalog, with a mixture of spectrum-luminosity classes, to derive the position of the Galactic plane. The reduction technique, mixed total least squares-least squares, takes into account the errors in the parallaxes, and the condition that the direction cosines of the Galactic pole have unit Eucl…
Reconstructed 3-d magnetic field structure and hard X-ray two ribbons for 2000 Bastille-day event
Yan, Yihua; Huang, Guangli
The Bastille-day event in 2000 produced energetic 3B/X5.6 flare with a halo CME, which had great geo-effects consequently. This event has been studied extensively and it is considered that it follows the two-ribbon flare model. The flare/CME event was triggered by an erupting filament and TRACE observations showed formation of giant arcade structu…