Search Publications
The Sun as an X-ray star: Active region evolution, rotational modulation, and implications for stellar X-ray variability
Orlando, S.; Peres, G.; Reale, F.
We study the contribution of an active region and its core to the luminosity and the spectrum of the Sun in the X-ray band and to the relevant solar emission measure vs. temperature distribution, EM(T). We also study the relevant changes in the course of four solar rotations, and the solar rotational modulation due to this active region, the only …
Variability of the EUV quiet Sun emission and reference spectrum using SUMER
Kretzschmar, M.; Lilensten, J.; Aboudarham, J.
This paper aims to build a quiet Sun EUV reference spectrum from the SOHO - SUMER database. We make use of 750 quiet Sun spectra spread over a large range of solar activity. They are carefully calibrated both in terms of frequency and intensity. The data do not show any noticeable variations versus the solar activity. This allows us to build a qui…
ISO deep far-infrared survey in the ``Lockman Hole''. III. Catalogs and source counts at 90 & 170 µm
Sanders, D. B.; Kawara, K.; Taniguchi, Y. +7 more
We present the catalogs and source counts for the C90 (reference wavelength of 90 µm) and C160 (170 µm) bands, which were extracted from our analysis of an ISO deep far-infrared survey conducted as part of the Japan/UH ISO cosmology project. The total survey area is ∼0.9 deg2 in two fields within the Lo…
Simultaneous observations of Jovian quasi-periodic radio emissions by the Galileo and Cassini spacecraft
Gurnett, D. A.; Hospodarsky, G. B.; Kurth, W. S. +4 more
The gravity-assist flyby by Cassini of Jupiter on 30 December 2000 and the extended Galileo orbital mission provided a unique opportunity to obtain simultaneous measurements with two spacecraft of many Jovian plasma wave and radio emissions. One of these emissions is Jovian type III radio emissions, also known as Jovian quasi-periodic (QP) emissio…
The Ultraviolet and Optical Spectra of Luminous B-Type Stars in the Small Magellanic Cloud
Lennon, D. J.; Evans, C. J.; Walborn, N. R. +2 more
We present ultraviolet spectra from the Space Telescope Imaging Spectrograph (STIS) of 12 early B-type stars in the Small Magellanic Cloud (SMC), composed of nine supergiants and three giants. A morphological comparison with Galactic analogs is made using archival data from the International Ultraviolet Explorer (IUE). In general, the intensity of…
Double-damped Lyα Absorption: A Possible Large Neutral Hydrogen Gas Filament near Redshift z=1
Turnshek, David A.; Rao, Sandhya M.; Vanden Berk, Daniel +3 more
We report the discovery of two damped Lyα systems (DLAs) near redshift z=1 along a single quasar sight line (Q1727+5302) with neutral hydrogen column densities of NHI=(1.45+/-0.15)×1021 and (2.60+/-0.20)×1021 atoms cm-2. Their sight line velocity difference of 13,000 km s-1 corresponds to a pr…
Radio observations of HD 93129A: The earliest O star with the highest mass loss?
Benaglia, P.; Koribalski, B.
We present the results of radio continuum observations towards the open cluster Tr 14, where our main targets are the early-type O stars HD 93129A/B and HD 93128. The observations were carried out at 3 cm (8.64 GHz) and 6 cm (4.80 GHz) with the Australia Telescope Compact Array. Only HD 93129A (type O2 If*) was detected; we measure flux densities …
A giant molecular cloud falling through the heart of Cygnus A: clues to the triggering of the activity
Tadhunter, C. N.; Bellamy, M. J.
We present intermediate-resolution near-infrared long-slit spectroscopic data for the nearby radio galaxy Cygnus A (3C 405) (obtained with the NIRSPEC spectrograph on the Keck II telescope). The data reveal considerable complexity in the near-infrared emission-line kinematics, including line splittings of 200-350 km s-1 and a mixture of…
Modeling the Heating and Cooling of WZ Sagittae Following the 2001 July Outburst
Sion, Edward M.; Godon, Patrick; Cheng, Fuhua +5 more
Far Ultraviolet Spectroscopic Explorer and Hubble Space Telescope Space Telescope Imaging Spectograph spectra of the dwarf nova WZ Sge, obtained during and following the early superoutburst of 2001 July over a time span of 20 months, monitor changes in the components of the system during its different phases. The synthetic spectral fits to the dat…
Solar Fast-Wind Regions as Sources of Shock Energetic Particle Production
Kahler, S. W.
If the production of solar energetic particles (SEPs) near the Sun is due to shocks driven by coronal mass ejections (CMEs), then two factors might favor SEP acceleration in slow rather than fast solar wind streams. The first is that both the MHD fast-mode and solar wind flow speeds are higher in the fast-wind streams. The second is that shock see…