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From the Sun's south to the north pole - Ulysses COSPIN/LET composition measurements at solar maximum
Sanderson, T. R.; Marsden, R. G.; Tranquille, C. +1 more
Based on elemental abundance ratios derived from the Ulysses COSPIN/LET measurements, we classified the energetic particle populations during and after the socalled Fast Latitude Scan - the time period during which the Ulysses spacecraft traveled from the highest heliolatitude south to maximum northern latitude, i.e. 27 November 2000 to 13 October…
Photometric studies of very metal-deficient blue compact dwarf galaxies: the exponential ionized gas halo of IZw18
Thuan, T. X.; Izotov, Y. I.; Papaderos, P. +4 more
Using HST and ground-based optical and NIR imaging data, we investigate whether the blue compact dwarf (BCD) galaxy I Zw 18 possesses an extended low-surface brightness (LSB) old stellar population underlying its star-forming (SF) regions. We show that the exponential intensity decrease observed in the filamentary LSB envelope of the BCD out to 18…
Pile-up on X-ray CCD instruments
Ballet, J.
Pile-up occurs on X-ray CCDs when several photons hit the detector at the same place between two readouts. In that case they are counted as one (or not at all) and their energies are summed. Pile-up thus affects both flux measurements and spectral characterisation of bright sources. Here I extend a previous work on flux loss, and present a simple …
Multiwavelength imaging of kpc-scale jets in AGN with Chandra and HST
Sambruna, Rita M.
I highlight recent developments from Chandra and HST observations of kpc-scale jets in AGN, with particular emphasis on our survey of 17 radio jets in a sample of FR II radio galaxies. These observations show that: (1) X-ray and optical emission is common from kpc-scale jets, (2) a large fraction of the bolometric luminosity is emitted at X-rays, …
Comparative study of the dust emission of 19P/Borrelly (Deep space 1) and 1P/Halley
Soderblom, L. A.; Thomas, N.; Ho, T. M. +2 more
Images obtained by the Miniature Integrated Camera and Imaging Spectrometer (MICAS) experiment onboard the Deep Space 1 spacecraft which encountered comet 19P/Borrelly on September 22nd 2001 show a dust coma dominated by jets. In particular a major collimated dust jet on the sunward side of the nucleus was observed. Our approach to analyse these f…
The dynamic 3D heliosphere: Implications for and new sources of its energetic particles
McComas, D. J.; Schwadron, N. A.
In recent years, two important aspects of heliospheric physics have emerged: (1) the intrinsic dynamism of the Sun's open magnetic flux and its vast importance for energetic particle propagation and acceleration; and (2) the importance of heliospheric grain populations for the production of energetic particles and anomalous cosmic rays. These new …
Stereoscopic observations of the giant hard X-ray/gamma-ray solar flare on 1991 June 30 at 0255 UT
Hurley, K.; Kane, S. R.; Vilmer, N. +3 more
The hard X-ray/gamma-ray (HXR/GR) impulsive burst on 1991 June 30 ( ~ 0255 UT) was associated with a flare which occured between 2degr and 12degr behind the east limb of the Sun. The partially occulted HXR/GR emission from this flare was detected at up to 100 MeV by three instruments on Earth-orbiting spacecraft: the Burst and Transient Source Exp…
Proper Motions of Stellar Jets as Observed with HST: The Movies
Hartigan, P. M.
The brightest stellar jets are close enough that they exhibit definite proper motions over a period of a few years when observed with the Hubble Space Telescope (HST). Results for the HH 1, HH 34, HH 47, and HH 111 jets, based on H alpha and [S II] HST images separated by about five years, are now available. A new interpolation algorithm for movin…
The spatial correlation of the non-thermal velocities for O IV and Si IV in the lower transition region
Doschek, G. A.; Mariska, J. T.; Akiyama, S.
We analyze the spatial relationship between non-thermal velocities derived from spectral lines of O IV. λ1401.16 (1.6×105 K) and Si IV λ1402.77 (6.3x10 4 K) in the solar lower transition region. The lines formed at different temperatures are observed simultaneously and at the same locations on the solar disk by the Solar Ultraviolet Mea…
Spectral Line Profile Correction of the Detector Effect: for a SOHO/UVCS Spectrometer
Nakagawa, Akinari
It has been noticed that observed spectral line profiles by the SOHO ultraviolet coronagraph spectrometer (SOHO/UVCS) are contaminated by a so-called detector effect, and an iterative correction of observed profiles by convolution with a zero-integral function has been employed to remove this unwanted effect on UVCS detectors. It is shown here tha…