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Strongly absorbed quiescent X-ray emission from the X-ray transient XTE J0421+56 (CI Cam) observed with XMM-Newton
Orlandini, M.; Parmar, A. N.; Boirin, L. +3 more
We have observed the X-ray transient XTE J0421+56 in quiescence with XMM-Newton. The observed spectrum is highly unusual being dominated by an emission feature at ~ 6.5 keV. The spectrum can be fit using a partially covered power-law and Gaussian line model, in which the emission is almost completely covered (covering fraction of 0.98 -0.06
The FERRUM Project: Experimental oscillator strengths of the UV 8 multiplet and other UV transitions from the y6P levels of Fe II
Nilsson, H.; Johansson, S.; Hibbert, A. +2 more
We report on experimental branching fractions (BFs) for 19 transitions from the three 3d5(6S)4s4p(3P) y6P levels in Fe II, measured in Fourier transform spectra of a Penning discharge lamp and a hollow cathode lamp. The transition wavelengths span the interval between 1600 and 2850 Å. Absolute oscillator…
The ISO-SWS post-helium atlas of near-infrared stellar spectra
de Graauw, T.; Feuchtgruber, H.; Salama, A. +11 more
We present an atlas of near-infrared spectra (2.36 mu m-4.1 mu m) of ~ 300 stars at moderate resolution (lambda /delta lambda ~ 1500-2000). The spectra were recorded using the Short-Wavelength Spectrometer aboard the Infrared Space Observatory (ISO-SWS). The bulk of the observations were performed during a dedicated observation campaign after the …
Discovery of an Old, Nearby, and Overlooked Supernova Remnant Centered on the Southern Constellation Antlia Pneumatica
McCullough, P. R.; Fields, Brian D.; Pavlidou, Vasiliki
We report the discovery of a supernova remnant (SNR) with an angular diameter of 24°, centered on the southern constellation Antlia Pneumatica. The SNR is detected well in Hα and X-rays. Within the Antlia SNR's outline, a marginally significant feature is detected in the 1.8 MeV gamma-ray line of the radioisotope 26Al. At an estimated d…
The O I Line Emission in Active Galactic Nuclei Revisited
Pastoriza, M. G.; Prato, L.; Rodríguez-Ardila, A. +2 more
UV, visible, and near-infrared spectroscopy is used to study the transitions of neutral oxygen leading to the emission of broad O I λ8446, λ11287, and λ1304 in active galactic nuclei. From the strength of the former two lines, contrary to the general belief, we found that in six of seven galaxies, Lyβ fluorescence is not the only mechanism respons…
HST STIS observations of four QSO pairs
Surdej, J.; Cristiani, S.; Petitjean, P. +3 more
We present HST STIS observations of four quasar pairs with redshifts 0.84<zem<1.56 and angular separation 2-3 arcmin corresponding to ~ 1-1.5 h-150 Mpc transverse proper distance at z ~ 0.9. We study the distribution of velocity differences between nearest neighbor \transi{H}i Lyman-alpha absorption lines det…
Polar Coronal Jets at Solar Minimum
Gurman, J. B.; Raymond, J. C.; Dobrzycka, D. +2 more
We present an analysis of six polar coronal jets observed by the Ultraviolet Coronagraph Spectrometer (UVCS) at solar minimum (1996). Four of the events were also recorded by the Extreme-Ultraviolet Imaging Telescope (EIT) and/or the Large Angle Spectrometric Coronagraph (LASCO) C2 coronagraph. We compared the jets with others recorded in 1997. We…
Models for solar magnetic loops. II. Comparison with SOHO-CDS observations on the solar disk
Solanki, S. K.; Landini, M.; Brković, A. +2 more
The present work describes a detailed comparison between SOHO-CDS observations of active region loops with a static, isobaric loop model developed assuming a temperature-independent heating function in the energy balance equation and a variable loop cross-section. The loop model is described in Landini & Landi (2002). Observations of an active…
Searching for the Signature of the Magnetic Fields at the Base of the Solar Convection Zone with Solar Cycle Variations of p-Mode Travel Time
Chou, Dean-Yi; Serebryanskiy, Alexander
We study the solar cycle variations of the solar p-mode travel time for different wave packets to probe the magnetic fields at the base of the solar convection zone. We select the wave packets that return to the same spatial point after traveling around the Sun with integral number of bounces. The change in one-bounce travel time at solar maximum …
Calcium to hydrogen line ratios in solar prominences
Heinzel, P.; Gouttebroze, P.
The ratio of Ca II 8542 Å to Hβ line intensities has been used for a long time to diagnose the gas pressure in solar prominences. In this paper we reconsider the theoretical dependence of E(8542)/E(Hβ ) on the gas pressure, as originally computed by Heasley & Milkey (1978), and extend this theoretical correlation to higher pressures. Firstly, …