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Venus wind map at cloud top level with the MTR/THEMIS visible spectrometer, I: Instrumental performance and first results
Widemann, Thomas; Gaulme, Patrick; Schmider, François-Xavier +3 more
Solar light gets scattered at cloud top level in Venus' atmosphere, in the visible range, which corresponds to the altitude of 67 km. We present Doppler velocity measurements performed with the high resolution spectrometer MTR of the Solar telescope THEMIS (Teide Observatory, Canary Island) on the sodium D2 solar line (5890A˚). Observations lasted…
Observation of Very High Energy Gamma Rays from HESS J1804-216 with CANGAROO-III Telescopes
Katagiri, H.; Edwards, P. G.; Gunji, S. +46 more
We observed the unidentified TeV gamma-ray source HESS J1804-216 with the CANGAROO-III atmospheric Cerenkov telescopes from 2006 May to July. We detected very high energy gamma rays above 600 GeV at the 10 σ level in an effective exposure of 76 hr. We obtained a differential flux of (5.0 +/- 1.5stat+/- 1.6sys) × 10-12
Changes in the photospheric magnetic field associated with solar flares
Lin, Jun; Mei, Zhixing
The flare-related, persistent and abrupt changes in the photospheric magnetic field have been reported by many authors during recent years. These bewildering observational results pose a challenge to the current flare theories in which the photospheric magnetic field usually remains unchanged in the eruption. In this paper, changes in the photosph…
SAX J1712.6-3739: a persistent hard X-ray source as monitored with INTEGRAL
Fiocchi, M.; Ubertini, P.; Bazzano, A. +1 more
Context: The X-ray source SAX J1712.6-3739 is a very weak low mass X-ray binary discovered in 1999 with BeppoSAX and located in the Galactic Center. This region has been intensively investigated by the INTEGRAL satellite with an unprecedented exposure time, providing an unique opportunity to study the hard X-ray behavior also for weak objects.
Reconstruction of the trajectory of the Huygens probe using the Huygens Atmospheric Structure Instrument (HASI)
Fulchignoni, M.; Leese, M. R.; Hathi, B. +13 more
The Huygens probe returned scientific measurements from the atmosphere and surface of Titan on 14 January 2005. Knowledge of the trajectory of Huygens is necessary for scientific analysis of those measurements. We use measurements from the Huygens Atmospheric Structure Instrument (HASI) to reconstruct the trajectory of Huygens during its mission. …
Electromagnetic waves observed by Venus Express at periapsis: Detection and analysis techniques
Russell, C. T.; Wei, H. Y.; Zhang, T. L. +3 more
The magnetometer on Venus Express was designed to be able to obtain 128 Hz samples of the magnetic field from two sensors in a gradiometer configuration. This mode is used around periapsis to determine whether the signals reported at low altitudes near 100 Hz, had the properties of electromagnetic waves generated by electric discharges in the Venu…
NLTE modelling of the flaring atmosphere above sunspot
Heinzel, P.; Schmieder, B.; Li, H. +1 more
Aims: We performed an analysis of the solar flaring atmosphere above sunspots. During the flare on October 20, 2003 many flaring structures were observed projected onto the sunspots. We analysed the Hα and Ca II line profiles emitted by the ribbons partially overlapping the sunspots. In the penumbra, the line intensity in the far wings is lower th…
On the radial distribution of white dwarfs in the Galactic globular cluster omega Cen
Prada Moroni, P. G.; Degl'Innocenti, S.; Marchetti, E. +14 more
We present deep and accurate photometry (F435W, F625W, F658N) of the Galactic Globular Cluster omega Cen collected with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). We identified ≈ 6,500 white dwarf (WD) candidates and compared their radial distribution with that of Main Sequence (MS) stars. We found a mild evid…
Study of waves in the magnetotail region with cluster and DSP
Balogh, A.; Zhang, T. L.; Klecker, B. +6 more
The study of the neutral sheet is of fundamental importance in understanding the dynamics of the Earth’s magnetosphere. From the earliest observation of the magnetotail, it has been found that the neutral sheet frequently appears to be in motion due to changing solar wind conditions and geomagnetic activity. Multiple crossings of the neutral sheet…
Distribution of coronal heating in a solar active region
Gontikakis, C.; Contopoulos, I.; Dara, H. C.
Aims: We investigate the distribution of heating of coronal loops in a non-flaring solar active region, using a simple electrodynamic model: the random displacements of the loop footpoints, caused by photospheric plasma motions, generate electric potential differences between the footpoints and, as a result, electric currents flow along the loops,…