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High order spectral analysis of electron plasma oscillations in the electron foreshock

Gurnett, D. A.; Pickett, J. S.; Walker, S. N. +1 more

The electron foreshock is the region in which electrons that have been reflected from the shock propagate back upstream along the magnetic field lines forming electron beams. The process of relaxation of these beams is one of the fundamental topics in plasma physics. It involves numerous nonlinear processes. High order spectral analysis is applied…

Inverse projection method for determination of distribution of real CME latitudes applied to the 1997-1998 SOHO LASCO observations

Skirgiello, Marta

Coronograph observations of coronal mass ejections (CMEs) do not provide the real latitude of their origin. The registered apparent latitude is the projection of the CME trajectory on the plane of the sky, and it may considerably differ from their original location. We show in this paper, how the projection effects can be eliminated from CME latit…

Solar radio observations and development of coronal mass ejections

Pick, M.; Maia, D.; Marqué, Ch.

We present in this study a synthesis of results on the initiation and development of CMEs using coordinated observations from SOHO and ground-based instruments. The emphasis is placed on radio spectral and imaging data. One important goal of this study is the identification of radio signatures of CMEs providing information below one solar radius a…

IBIS performances during the Galactic Plane Scan. I. The Cygnus region

Rodriguez, J.; Foschini, L.; Capitanio, F. +8 more

The Plane of our Galaxy is regularly observed by the INTEGRAL satellite by means of scheduled scans. We present here results from the IBIS/ISGRI instrument using data from the first two Galactic Plane Scans performed at the end of the Performance Verification phase, while INTEGRAL was pointed towards the Cygnus region.

Considering the predict…

The Infrared Spectral Energy Distribution of the Seyfert 2 Prototype NGC 5252

Acosta-Pulido, J. A.; Prieto, M. Almudena

The complete mid- to far-infrared continuum energy distribution collected with the Infrared Space Observatory of the Seyfert 2 prototype NGC 5252 is presented. ISOCAM images taken in the 3-15 µm show a resolved central source that is consistent at all bands with a region of about 1.3 kpc in size. Because of the lack of ongoing star formation…

Some statistical aspects of estimating the local red clump absolute magnitude

Koen, Chris; Lombard, Fred

Various statistical issues regarding estimation of the mean absolute magnitude of the red clump stars, using Hipparcos parallaxes, are discussed. The problem is put in the broader context of estimation of the functional dependence of the absolute magnitude on colour of local giant stars, as derived from Hipparcos observations. The methods used inc…

Near-infrared photometry of 20 hipparcos carbon stars

Chen, Pei-Sheng; Yang, Xiao-Hong; Wang, Xun-Hao

Near-infrared JHK photometry was carried out for 20 carbon stars observed by the satellite Hipparcos. From the observations, bolometric corrections in the K band ( BC_K), apparent bolometric magnitudes ( m_rmbo) and effective temperatures ( T_e) of these stars were estimated. Combined with the trigonometric parallaxes…

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 …