Search Publications
Discovery of the optical counterpart to the X-ray pulsar SAX J2103.5+4545
Reig, P.; Negueruela, I.; Fabregat, J. +3 more
We report optical and infrared photometric and spectroscopic observations that identify the counterpart to the 358.6-s X-ray transient pulsar
Long-term evolution of FU Orionis objects at infrared wavelengths
Prusti, T.; Csizmadia, Sz.; Ábrahám, P. +3 more
We investigate the brightness evolution of seven FU Orionis systems in the 1-100 µm wavelength range using data from the Infrared Space Observatory (ISO). The ISO measurements were supplemented by 2MASS and MSX observations performed in the same years as the ISO mission (1995-98). The spectral energy distributions (SEDs) based on these data …
Optical nuclei of radio-loud AGN and the Fanaroff-Riley divide
Kharb, P.; Shastri, P.
We investigate the nature of the point-like optical nuclei that have been found in the centres of the host galaxies of a majority of radio galaxies by the Hubble Space Telescope. We examine the evidence that these optical nuclei are relativistically beamed, and look for differences in the behaviour of the nuclei found in radio galaxies of the two …
An all-sky optical catalogue of radio/X-ray sources
Hardcastle, M. J.; Flesch, E.
We present an all-sky catalogue that aligns and overlays the ROSAT HRI, RASS, PSPC and WGA X-ray catalogues and the NVSS, FIRST and SUMSS radio catalogues onto the optical APM and USNO-A catalogues. Objects presented are those APM/USNO-A optical objects which are calculated with ≥ 40% confidence to be associated with radio/X-ray detections, or whi…
X-ray spectroscopy on Abell 478 with XMM-Newton
Kaastra, J. S.; de Plaa, J.; Pointecouteau, E. +3 more
We report the results from a spatially resolved spectroscopy study with XMM-Newton on the relaxed cluster of galaxies
Hα variability of the recurrent nova T Coronae Borealis
Marziani, P.; Zamanov, R.; Stanishev, V. +1 more
We analyze Hα observations of the recurrent nova
Identification of emission lines in the low-ionization strontium filament near Eta Carinae
Smith, N.; Johansson, S.; Hartman, H. +2 more
We have obtained deep spectra from 1640 to 10 100 Å with the Space Telescope Imaging Spectrograph (STIS) of the strontium filament, a largely neutral emission nebulosity lying close to the very luminous star Eta Carinae and showing an uncommon spectrum. Over 600 emission lines, both permitted and forbidden, have been identified. The majority origi…
Spectroscopic measurement of the plasma electron density and outflow velocity in a polar coronal hole
Giordano, S.; Antonucci, E.; Noci, G. +2 more
A new spectroscopic method, aimed to derive the plasma electron density and outflow velocity in expanding solar coronal regions, is discussed in this paper. The method is based on the analysis of a pair of coronal lines emitted via collisional and radiative excitation by the same ion, such as the O VI 1032, 1037 Å, doublet. The merit of this techn…
Effect of spatial resolution on estimating the Sun's magnetic flux
Solanki, S. K.; Krivova, N. A.
A critical question related to a possible secular trend in the Sun's total magnetic flux and consequently in solar irradiance is the total amount of magnetic flux present on the Sun and how it is distributed between active regions and the quiet Sun. NSO/Kitt Peak synoptic charts have in the past been used to estimate the total flux and the fractio…
The nuclear ring in the unbarred galaxy NGC 278: Result of a minor merger?
Knapen, J. H.; van der Hulst, J. M.; de Blok, W. J. G. +1 more
We present fully sampled high angular resolution two-dimensional kinematics in the Hα spectral line, optical and near-infrared imaging, as well as 21 cm atomic hydrogen data of the spiral galaxy NGC 278. This is a small non-barred galaxy, which has a bright star forming inner region of about 2 kpc in diameter, reminiscent of nuclear rings seen mai…