Search Publications
Dispersive Alfvén Waves Observed by Cluster at the Magnetopause
Khotyaintsev, Y.; Stasiewicz, K.; Grzesiak, M.
We have analyzed ELF turbulence ∼0.03 - 10 Hz) observed by Cluster at the magnetopause layer during 120 multiple magnetopause crossings on a single event, December 31, 2000, 09-16 UT. Multiple crossings are produced by nonlinear, large amplitude surface waves at the magnetopause. Waves below the proton gyrofrequency fci ≈ 0.3 Hz) are identified as…
Imaging principles and techniques in space-borne gamma-ray astronomy
Schönfelder, Volker
Gamma-ray astronomy in the photon energy band from several 100keV up to say 10GeV can only be performed from space. Tremendous progress has been made in this young research field during the last 40 years. All-Sky maps exist now in continuum and line emission and short gamma-ray bursts-lasting only seconds-can be located to better than 1arcmin. The…
Total Solar Irradiance Variation During Rapid Sunspot Growth
Fröhlich, Claus; Zahid, H. Jabran; Hudson, Hugh S.
Large sunspot areas correspond to dips in the total solar irradiance (TSI), a phenomenon associated with the local suppression of convective energy transport in the spot region. This results in a strong correlation between sunspot area and TSI. During the growth phase of a sunspot other physics may affect this correlation; if the physical growth o…
An Optical and X-Ray Examination of Two Radio Supernova Remnant Candidates in 30 Doradus
Chu, You-Hua; Gruendl, Robert A.; Chen, C. -H. Rosie +2 more
The giant H II region 30 Doradus is known for its violent internal motions and bright diffuse X-ray emission, suggesting the existence of supernova remnants (SNRs), but no nonthermal radio emission has been detected. Recently, Lazendic et al. compared the Hα/Hβ and radio/Hα ratios and suggested two small radio sources to be nonthermal and thus SNR…
Is T Leonis a superoutbursting intermediate polar?
Schmitt, J. H. M. M.; Ness, J. -U.; Vrielmann, S.
We present an XMM-Newton analysis of the cataclysmic variable T Leo. The X-ray light curve shows sinusoidal variation on a period Px equal to 0.89+0.14-0.10 times the previously spectroscopically determined orbital period. Furthermore, we find a signal in the power spectrum at 414 s that could be attributed to the …
Quantitative interpretation of the rotation curves of spiral galaxies at redshifts z ∼ 0.7 and z ∼ 1
Böhm, A.; Ziegler, B. L.; Möllenhoff, C. +1 more
We present decompositions of the rotation curves of three spiral galaxies at redshifts z ∼ 0.7 and 1 into contributions by their bulges, disks, and dark halos, respectively. In order to set constraints on the degeneracy of the decompositions we interpret the morphology of the spiral structures quantitatively in the framework of density wave theory…
Do X-ray plasma ejections accelerate Coronal Mass Ejections?
Tomczak, M.
The X1.2 flare occurred on 23 April 1998 approximately 13° behind the eastern solar limb. Its C2.0 precursor is identified as a rapidly expanding system of magnetic loops that was well-observed by Yohkoh. Basic parameters of this ejection are estimated based on images from the SXT telescope. The evolution of the X-ray ejection is compar…
Inferring the coronal flaring patterns in active galactic nuclei from reverberation maps
Lasenby, A. N.; Goyder, R.
The relativistically broadened iron Kα line at 6.4 keV observed in the Seyfert 1 galaxy MCG-6-30-15 has provided a probe of the strong-gravity environment near a black hole, in particular suggesting that it is rapidly spinning. An important variable in such analyses is the geometry of the illuminating source. We present a new technique that constr…
Newly Identified Forbidden Transitions within the Ground Configuration of Ions of Very Low Abundance P, Cl, K, and Co
Curdt, W.; Landi, E.; Feldman, U.
Forbidden lines from transitions within the ground configuration of highly ionized atoms occupy an important role in diagnosing the properties of astrophysical plasmas. In this paper we report the identification of forbidden lines in the 500-1500 Å range from transitions within the ground configuration of highly ionized ions of the very low abunda…
Localization of wave fields in lower hybrid cavities
André, M.; Eriksson, A.; Tjulin, A.
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