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The Obscuring Starburst of NGC 6221 and Implications for the Hard X-Ray Background
Storchi-Bergmann, T.; Heckman, T. M.; Levenson, N. A. +2 more
We present NGC 6221 as a case study of ``X-ray-loud composite galaxies,'' which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in X-rays. The net optical spectrum of NGC 6221 is properly characterized as a starburst galaxy, but in X-rays, NGC 6221 is similar to Seyfert 1 galaxies, exhibiting a p…
Intensity Ratios between the 2s2 1S0-2s2p 3P1 and 2s2p 1P1-2p2 1D2 Transitions in Be-like Ions as Electron Temperature Indicators for Solar Upper Atmosphere Plasmas
Landi, E.; Doschek, G. A.; Feldman, U. +1 more
We investigate the relative intensities of the two moderately bright Be-like 2s2 1S0-2s2p 3P1 and 2s2p 1P1-2p2 1D2 lines as a function of electron temperature. We show that the intensity ratios of the lines in the beryllium isoelectronic s…
Cold gas kinematics in an L* spiral Galaxy at z = 0.437: The nature of Damped Lyman-alpha absorbers
de Bruyn, A. G.; Briggs, F. H.; Vermeulen, R. C.
Westerbork Radio Synthesis Telescope observations of the redshifted 21 cm line absorber against the zem = 0.871 double lobed quasar 3C 196 show that the intervening absorber is an L~ L* spiral galaxy (3C 196-G1) and that the absorbing layer of cold gas extends to radii of at least 30 h50-1 kpc. The new d…
Mg II Absorber Number Density at z~=0.05: Implications for ΩDLA Evolution
Churchill, Christopher W.
An unbiased sample of 147 quasar/active galactic nuclei spectra, obtained with the Faint Object Spectrograph on board the Hubble Space Telescope, has been searched for intervening Mg II λλ2796, 2803 absorbers over the redshift range 0<z<=0.15. The total redshift path searched is 18.8, with the survey being 80% complete to a 5 σ rest-frame eq…
High-resolution O VI absorption line observations at 1.2 <= z <= 1.7 in the bright QSO HE 0515-4414
Reimers, D.; Hagen, H. -J.; Baade, R. +1 more
STIS Echelle observations at a resolution of 10 km s-1 and UVES/VLT spectroscopy at a resolution of 7 km s-1 of the luminous QSO HE 0515-4414 (zem = 1.73, B = 15.0) reveal four intervening O Vi absorption systems in the redshift range 1.21 <= zabs <= 1.67 (1.38503, 1.41601, 1.60175, 1.67359). In ad…
A high resolution spectroscopic observation of CAL 83 with XMM-Newton/RGS
de Vries, C. P.; Heise, J.; Brinkman, A. C. +4 more
We present the first high resolution photospheric X-ray spectrum of a Supersoft X-ray Source, the famous CAL 83 in the Large Magellanic Cloud. The spectrum was obtained with the Reflection Grating Spectrometer on XMM-Newton during the Calibration/Performance Verification phase of the observatory. The spectrum covers the range 20-40 Å at an approxi…
On the relation between total irradiance and radius variations
Varadi, F.; Rozelot, J. P.; Pap, J. +1 more
We use Singular Spectrum Analysis (SSA) to analyze total solar irradiance variations and CERGA radius measurements. Total solar irradiance has been monitored from space for more than two decades, whilst ground-based radius measurements are available as a coherent time series from 1975. We compare these indicators to try to understand the origin of…
Physical Conditions in the Foreground Gas of Reflection Nebulae: NGC 2023, vdB 102, and NGC 7023
Federman, S. R.; Lambert, David L.; Yan, M. +2 more
High-resolution optical spectra of HD 37903 and HD 147009, which illuminate the reflection nebulae NGC 2023 and vdB 102, were obtained for comparison with our results for HD 200775 and NGC 7023. Ground-based measurements of the molecules CH, C2, and CN and the atoms Na I and K I were analyzed to extract physical conditions in the foregr…
NOTE: HST/FGS Observations of the Asteroid (216) Kleopatra
Lattanzi, M. G.; Tanga, P.; Berthier, J. +4 more
Interferometric observations of asteroid (216) Kleopatra were performed in January 2000 using the Fine Guidance Sensors (FGS) aboard HST. The FGS data obtained clearly suggest that (216) Kleopatra is composed of two lobes in contact, in agreement with the radar data (Ostro et al. 2000, Science288, 836-839), and provide more precise constraints on …
The first ISO ERO: A dusty quasar at z = 1.5
Cesarsky, C.; Lidman, C.; Pierre, M. +9 more
We report the discovery of an extremely red object (ERO) in a medium-deep ISOCAM extragalactic survey. The object is also a radio source. Subsequent VLT NIR spectroscopy revealed a prominent Hα line giving a redshift of 1.5. We present the spectrum and photometric data points and discuss evidence that ISO J1324-2016 is a quasar harbouring a signif…