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HST observation of the atmospheric composition of Jupiter's equatorial region: evidence for tropospheric C ₂H ₂

Griffith, Caitlin A.; Yelle, Roger V.; Bétrémieux, Yan

This paper presents the first detailed analysis of acetylene absorption features observed longward of 190.0 nm in a jovian spectrum by the Faint Object Spectrograph on board the Hubble Space Telescope. The presence of two features located near 207.0 nm can only be explained by a substantial abundance of acetylene in the upper troposphere. Using a …

Spectroscopic mode identification for the slowly pulsating B star HD 147394

Mathias, P.; Aerts, C.; Briquet, M. +2 more

We present ground-based high-resolution high S/N spectra of the slowly pulsating B star HD 147394. Two frequencies are clearly found in the moments of the Si II 4128-4130 doublet: f₁=0.8008 c d^-1 and f₂=0.7813 c d^-1. The frequency f₁ is also found in the HIPPARCOS data. A third frequency is al…

The metallicity of β Cephei stars on the basis of the satellite ultraviolet spectra

Niemczura, E.; Cugier, H.; Daszyńska, J.

We derive the mean stellar parameters like angular diameter, effective temperature, and metallicity from ultraviolet spectra for all β Cephei stars observed during the IUE satellite mission, including those belonging to the three open clusters. For this purpose we fit the theoretical flux distributions of Kurucz's models to observed low-resolution…

The Ultraviolet Continuum Emission of FR I and FR II Radio Galaxies and a Proposal for a Unified AGN Model for FR I sources

Baum, Stefi A.; Zirbel, Esther L.

This paper is the second in a series of two on the UV continuum emission (in the range from 1400 to 3700 Å) of radio galaxies that were extracted from the Hubble Space Telescope (HST) Archives. The sample consists of 31 3C and Parkes radio galaxies that have redshifts below 0.2 (the majority have redshifts of ~0.03) and radio powers of ~10^25<…

JEM-X observations of the Be/X-ray binary EXO 2030+375

Reig, P.; Kretschmar, P.; Lund, N. +3 more

We have used data from the Joint European Monitor (JEM-X) to perform an X-ray spectral and timing analysis of the 42-s transient pulsar EXO 2030+375 during an X-ray outburst. X-ray pulsations are clearly detected with an average pulse period of 41.66+/-0.05 s and an average pulse fraction of 60%. The profile of the energy spectrum did not change a…

Repeated Flaring from Loop-Loop Interaction

Pohjolainen, S.

A series of solar flares was observed near the same location in NOAA active region 8996 on 18-20 May 2000. A detailed analysis of one of these flares is presented where the emitting structures in soft and hard X-rays, EUV, Hα, and radio at centimeter wavelengths are compared. Hard X-rays and radio emission were observed at two separate loop footpo…

Simultaneous retrieval of optical depths and scattering phase functions in Titan's atmosphere from Huygens/DISR data

Keller, H. U.; Grieger, B.; Rodin, A. V. +1 more

In January 2005, the Huygens probe will descent through Titan's atmosphere and the Descent Imager/Spectral Radiometer (DISR) will perform upward and downward looking observations at various spectral ranges and spatial resolutions. One of the subinstruments, the Upward Looking Visible Spectrometer (ULVS), measures the total downward radiation flux …

X-ray observations of the Crab Pulsar and Nebula with JEM-X on INTEGRAL

Walter, R.; Schmidt, M.; Westergaard, N. J. +8 more

The Crab pulsar is the best studied rotation powered pulsar. We report the results obtained in the 3-35 keV energy band with the X-ray monitor, JEM-X, on ESAs recently launched gamma -ray mission, INTEGRAL.

Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the …

Nuclear Starburst Activity in the Seyfert 2 Galaxy NGC 2273

Gu, Qiu-Sheng; Lei, Shi-Jun; Shi, Lei +2 more

We present spectrophotometric results of the Seyfert 2 galaxy NGC 2273. The presence of high-order Balmer absorption lines (H8, H9, H10) and weak equivalent widths of CaII K λ3933, CN λ4200, G-band λ4300 and MgIb λ5173 clearly indicate recent star-forming activity in the nuclear region. Using a simple stellar population synthesis model, we find th…

Deriving effective sunspot temperatures from SOHO/VIRGO irradiance measurements. A starspot modelling approach

Hanslmeier, A.; Eker, Z.; Otruba, W. +2 more

A method is developed to obtain mean effective sunspot temperatures from satellite irradiance deficits. Using a formalism derived from a star spot modelling approach, this method only requires accurate positions and areas of sunspots - but not intensities. The method is applied to SOHO/VIRGO spectral solar irradiance (SSI) at 402, 500, and 862 nm …