Search Publications
Particle and X-ray damage in pn-CCDs
Meidinger, Norbert; Schmalhofer, Bernhard; Strüder, Lothar
The fully depleted pn-junction charge coupled device (pn-CCD) has been developed as a detector for X-ray imaging and high-resolution spectroscopy for the X-ray satellite missions XMM and ABRIXAS. If the detector is exposed to a particle radiation environment, the energy resolution is degraded due to charge transfer losses and a dark current increa…
Evolution of the Symbiotic Star AS338 after Its Strong Outburst in 1983
Munari, U.; Mikolajewska, J.; Kolotilov, E. A. +5 more
The photometric UBV observations of AS338 that we began after its outburst in 1983 are presented. They were accompanied by yearly spectroscopic observations and by occasional estimations of the star's infrared JHKL magnitudes. In June 1993, the star's optical spectrum was extended to the ultraviolet via IUE observations of AS338. Collectively, the…
The UV spectrum of nebulae
Zagury, Frédéric
This paper presents an analysis of the UV spectrum of some nebulae with clearly identified illuminating stars, all observed by the IUE satellite. The data show remarkable properties of the UV spectrum of the nebulae. Each spectrum is the product of the star spectrum and a linear function of 1/ λ. There is no peculiar behaviour in the spectrums at …
Composite spectraPaper 10: the equal-mass binary HR 2030 (K0IIb+B8IV)
Griffin, R. E. M.; Griffin, R. F.
We separate the spectra of the individual components of HR 2030, a sixth-magnitude composite-spectrum binary system, and show that they have types close to K0IIb and B8IV, and masses that are equal to within the precision of the measurements (mass ratio=1.00+/-0.03). The orbit appears to have a very small eccentricity, although reasons are given f…
Very Large Telescope Observations of the Peculiar Globular Cluster NGC 6712: Discovery of a UV, Hα-Excess Star in the Core
Ferraro, Francesco R.; Paresce, Francesco; De Marchi, Guido +1 more
We present results from multiband observations in the central region of the cluster NGC 6712 with the ESO Very Large Telescope. Using high-resolution images we have identified three UV-excess stars. In particular, two of them are within the cluster core, a few arcseconds apart: the first object is star ``S,'' which previous studies identified as t…
FIP effect measurements in the off-limb corona observed by SUMER on SOHO
Dwivedi, B. N.; Mohan, A.; Landi, E.
Systematic differences between elemental abundances in the corona and in the photosphere have been long acknowledged in the Sun; these abundance anomalies are correlated with the first ionization potentials (FIPs) of the elements. This correlation is called FIP effect. Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitte…
Origin of Helical Coronal Disturbances from the Sun
Hori, K.
By combining data from the Nobeyama Radioheliograph and the LASCO coronagraph aboard the SoHO spacecraft, we report two helical coronal disturbances accompanying white-light coronal mass ejections (CMEs). These are activated prominences at the base, rotating around each vertical axis while moving on the solar surface with projected speeds of >=…
Comparison of Parallaxes from Eclipsing Binaries Method with Hipparcos Parallaxes
Semeniuk, Irena
The parallaxes determined by Lacy (1979) by means of eclipsing binaries method are compared with the Hipparcos parallaxes for 19 systems. The residual scatter of the distance moduli inferred from eclipsing binaries method - after allowing for known errors as given by Lacy and Hipparcos - is equal to 0.18 mag. It decreases to 0.08 mag when obviousl…
Photometric Redshifts and Morphologies of Galaxies in the NICMOS Parallel Fields
Schneider, Glenn; Rieke, Marcia J.; Vacca, William D. +3 more
We present positions, magnitudes, sizes, and morphological classifications for 111 galaxies discovered in the Hubble Space Telescope NICMOS camera 1 and camera 2 parallel fields. We combine the magnitudes measured in the JHK-analog filters with those from deep ground-based images in V and/or R to measure photometric redshifts for 71 objects using …
Modeling the energy response of pn-CCDs in the 0.2-10 keV band
Hartmann, R.; Strüder, L.; Krause, N. +5 more
A simple analytical model has been developed to explain the shape of low-energy spectra taken with pn-CCDs, which are developed as imaging spectroscopic detectors for ESA's X-ray observatory satellite X-Ray Multimirror Mission (XMM). The model has been tested on experimental data taken with test devices at the German synchrotron Berliner Elektrone…