Search Publications
Microwave, Optical, EUV, and Hard X-Ray Signature of Possible Coronal Loop Interaction
Ji, Haisheng; Huang, Guangli
In this paper, we present a comprehensive picture for the M2.0 class flare of September 9, 2002 with an extensive multi-wavelength analysis. The flare was observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), the Owens Valley Solar Arrays (OVSA), and Big Bear Solar Observatory (BBSO). At BBSO, the observation was specially made a…
Bowen excitation of N III lines in symbiotic stars
Munari, U.; Wahlgren, G. M.; Johansson, S. +3 more
We present a semi-empirical equation for prediction of the strengths of those N III lines that are generated by the Bowen mechanism and observed in spectra of symbiotic stars. The equation assumes that the Bowen mechanism is the only source populating the 3d state in N III, and comparisons with observations of the 3s-3p and 3p-3d transitions serve…
Detection and analysis of a new INTEGRAL hard X-ray transient, IGR J17285-2922
Hill, A. B.; Capitanio, F.; Bird, A. J. +10 more
We present the transient nature of INTEGRAL source IGR J17285 2922, identified from a single period of activity during an IBIS/ISGRI Galactic Centre Deep Exposure in September 2003. The source has a maximum detection significance of 14σ in the 20 100 keV energy range and exhibits a flux of 6.5 mCrab before it moves out of the ISGRI field of view. …
Ion composition variations in the plasma sheet observed by Cluster/RAPID
Zong, Q. -G.; Daly, P. W.; Ruan, P. +5 more
Based on the energetic particle measurements obtained by Cluster/RAPID (Research with Adaptive Particle Imaging Detectors), ion composition variations in the plasma sheet have been investigated. By comparing observations during quiet and storm intervals, it is found that, in addition to the enhanced energy density for all ion species, the ratio of…
FORS spectroscopy of galaxies in the Hubble Deep Field-South
Berta, S.; Aussel, H.; Franceschini, A. +2 more
We present low resolution multi-object spectroscopy of an I-band magnitude limited (IAB ≃ 23-23.5) sample of galaxies located in an area centered on the Hubble Deep Field-South (HDFS). The observations were obtained using the Focal Reducer/low dispersion Spectrograph (FORS) on the ESO Very Large Telescope. Thirty-two primary spectroscop…
AGN variability time scales and the discrete-event model
Paltani, S.; Courvoisier, T. J. -L.; Favre, P.
We analyse the ultraviolet variability time scales in a sample of 15 type 1 Active Galactic Nuclei (AGN) observed by IUE. Using a structure function analysis, we demonstrate the existence in most objects of a maximum variability time scale of the order of 0.02-1.00 year. We do not find any significant dependence of these maximum variability time s…
Erupting Cataclysmic Variable Stars in the Nearest Globular Cluster, NGC 6397: Intermediate Polars?
Zurek, David R.; Knigge, C.; Hinkley, Sasha +2 more
NGC 6397 is the closest globular cluster and hence the ideal place to search for faint stellar populations such as cataclysmic variables (CVs). Hubble Space Telescope (HST) and Chandra observers have identified nine certain and likely CVs in this nearby cluster, including several magnetic CV candidates. We have combined our recent UV imagery with …
On the X-ray properties of OH megamaser sources: Chandra snapshot observations
Brandt, William N.; Comastri, Andrea; Vignali, Cristian +1 more
We present Chandra snapshot observations for a sample of seven sources selected from the Arecibo OH megamaser (OHM) survey at z~ 0.13-0.22 and with far-infrared (FIR) luminosities in excess of 1011Lsolar. In contrast with the known H2O megamasers, which are mostly associated with powerful active galactic nuclei (AG…
Statistical phase propagation and dispersion analysis of low frequency waves in the magnetosheath
Fränz, M.; Dandouras, I.; Glassmeier, K. -H. +3 more
We present the results of a statistical analysis of low-frequency fluctuations in the high latitude regions of the dayside magnetosheath using CLUSTER as a wave telescope. Magnetic field observations are used to determine wave propagation directions and wave numbers for selected frequencies. Using observations of the plasma flow velocity we correc…
Latitudinal Distribution of Solar Flares and Their Association with Coronal Mass Ejections
Shrivastava, Pankaj K.; Singh, Neelam
Major solar flare events have been utilised to study the latitudinal frequency distribution of solar flares in northern and southern hemispheres for the period of 1986 to 2003. A statistical analysis has been performed to obtain the correlation between Coronal Mass Ejections (CMEs) and Forbush decrease (Fds) of cosmic ray intensity. Almost the sam…