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Magnetic Activity Associated With Radio Noise Storms
van Driel-Gesztelyi, L.; Bentley, R. D.; Klein, K. -L. +4 more
As it crossed the solar disk in May and June 1998, AR 8227 was tracked by TRACE, Yohkoh, SOHO, and many ground-based observatories. We have studied how the evolution of the magnetic field resulted in changes in activity in the corona. In particular, we examine how the evolving field may have led to the acceleration of electrons which emit noise st…
The multiple system LHS 1070: a case study for the onset of dust formation in the atmospheres of very low mass stars
Hauschildt, Peter H.; Richichi, Andrea; Leinert, Christoph +1 more
Atomic data from the IRON Project. XL. Electron impact excitation of the Fe XIV EUV transitions
Young, P. R.; Mason, H. E.; Storey, P. J.
We calculate collision strengths and thermally averaged collision strengths for electron excitation between the forty energetically lowest levels of Fe13+. The scattering calculation is more complete than any previous work on this ion and significant differences are found in the excitation rates for many of the extreme ultra-violet (EUV…
Modelling solar irradiance variations: Comparison with observations, including line-ratio variations
Solanki, S. K.; Unruh, Y. C.; Fligge, M.
Solar irradiance variations show a strong temporal and spectral dependence. The progression of the Sun through its activity cycle as well as solar rotation are mirrored in the irradiance variations. The spectral dependence is such that the variations are several magnitudes larger in the EUV than in the visible or infrared. We present a simple 3-co…
HST ultraviolet observations of rapid variability in the accretion-disc wind of BZ Cam
Ringwald, F. A.; Prinja, Raman K.; Knigge, Christian +1 more
We present results from time-resolved Hubble Space Telescope (HST) GHRS ultraviolet spectroscopy of the nova-like cataclysmic variable BZ Cam. Extensive changes are recorded in the extended absorption troughs of the UV resonance line profiles, which betray a highly unsteady and continuously variable supersonic outflow. The large-scale line-profile…
Multi-wavelength study of the slow ``disparition brusque" of a filament observed with SOHO
Schmieder, B.; Delannée, C.; Yong, Deng Yuan +2 more
A mid-latitude filament was observed before and after its eruption with SOHO (EIT, SUMER, CDS and LASCO) and with ground based observatories (Meudon and Pic du Midi) in the context of a coordinated MEDOC campaign in Orsay. The eruption was followed by a large Coronal Mass Ejection well observed by LASCO. Few hours before its eruption, the filament…
Highly polarized structures in the near-nuclear regions of Cygnus A: intrinsic anisotropy within the cones?
Tadhunter, C. N.; Packham, C.; Sparks, W. +6 more
We present near-infrared imaging polarimetry observations of the nucleus of Cygnus A (z= 0.0567), taken with the NICMOS camera of the Hubble Space Telescope (HST) at a wavelength of 2.0µm. These maps reveal a highly collimated region of polarized emission straddling the nucleus and extending to a radius of 1.2arcsec. Remarkably, this feature…
Radio Tracking of a White-Light Coronal Mass Ejection from Solar Corona to Interplanetary Medium
Plunkett, S. P.; Kaiser, M. L.; Reiner, M. J. +2 more
For a solar flare/coronal mass ejection (CME) event on 1999 May 3, type II radio emissions were observed from the metric through the hectometric wavelength regimes. By comparing the dynamics of the CME with that implied by the frequency range and frequency drift rates of the type II radio emissions, it is concluded that the decametric-hectometric …
Space Telescope Imaging Spectrograph Echelle Observations of NGC 4151: Variable Ionization of the Intrinsic UV Absorbers
Gull, T. R.; Kraemer, S. B.; Crenshaw, D. M. +5 more
We present echelle observations of the intrinsic UV absorption lines in the Seyfert galaxy NGC 4151; these observations were obtained with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope on 1999 July 19. The UV-continuum flux at 1450 Å decreased by factor of about 4 over the previous 2 years, and there was a correspondin…
Anatomy of the counterrotating molecular disk in the spiral NGC 3593. 12CO(1-0) interferometer observations and numerical simulations
Hunt, L. K.; Combes, F.; García-Burillo, S. +2 more
This paper presents high-resolution (4arcsec x3arcsec ) interferometer observations of the inner disk of the starburst spiral NGC 3593, made in the (1-0) line of 12CO. NGC 3593 is an early-type system known to possess two counterrotating stellar disks of markedly different scale lengths and masses. The CO emission comes from a highly st…