Search Publications
Study of the Three-Dimensional Shape and Dynamics of Coronal Loops Observed by Hinode/EIS
Gontikakis, C.; Tsinganos, K.; Georgoulis, M. K. +2 more
We study plasma flows along selected coronal loops in NOAA Active Region 10926, observed on 3 December 2006 with Hinode'sEUVImaging Spectrograph (EIS). From the shape of the loops traced on intensity images and the Doppler shifts measured along their length we compute their three-dimensional (3D) shape and plasma flow velocity using a simple geome…
Polarimetric coronagraphy of BD + 31°643
Olofsson, G.; Florén, H. -G.; Nilsson, R. +2 more
Context. The binary B5 V star BD + 31°643 exhibits a disk-like structure detected at optical wavelengths. Even though the feature is well centered on the star, it has been argued, based on Spitzer observations, that the feature is a filament not directly associated to the binary star.
Aims: The purpose of the present paper is to investigate w…
Is there a compact companion orbiting the late O-type binary star HD 164816?
Neuhäuser, R.; Stahl, O.; Chini, R. +7 more
We present a multi-wavelength (X-ray, γ-ray, optical and radio) study of HD 164816, a late O-type X-ray detected spectroscopic binary. X-ray spectra are analysed and the X-ray photon arrival times are checked for pulsation. In addition, newly obtained optical spectroscopic monitoring data on HD 164816 are presented. They are complemented by availa…
Magnetism in Massive Stars
Henrichs, H. F.
Stars with mass more than 8 solar masses end their lives as neutron stars, which we mostly observe as highly magnetized objects. Where does this magnetic field come from? Such a field could be formed during the collapse, or is a (modified) remnant of a fossil field since the birth of the star, or otherwise generated by a dynamo during its lifetime…
Reversed Drifting Quasi-periodic Pulsating Structure in the X1.3 Solar Flare on 30 July 2005
Wang, Rui; Tan, Baolin; Tan, Chengming +1 more
Based on the analysis of the microwave observations at the frequency range of 2.60 - 3.80 GHz in the solar X1.3 flare event observed at the Solar Broadband RadioSpectrometer in Huairou (SBRS/Huairou) on 30 July 2005, an interesting reversed drifting quasi-periodic pulsating structure (R-DPS) is confirmed. The R-DPS is mainly composed of two drifti…
Ortho-to-para Ratio Studies of Shocked H2 Gas in the Two Supernova Remnants IC 443 and HB 21
Lee, Ho-Gyu; Moon, Dae-Sik; Shinn, Jong-Ho
We present near-infrared (2.5-5.0 µm) spectral studies of shocked H2 gas in two supernova remnants, IC 443 and HB 21, which are well known for their interactions with nearby molecular clouds. The observations were performed with the Infrared Camera aboard the AKARI satellite. At the energy range 7000 K lsim E(\upsilon,J) lsim 20,0…
A Survey of the Hard X-Ray Characteristics of Seismically Active and Quiet White-Light Flares
Matthews, S. A.; Pedram, E.
Various mechanisms have been proposed to explain how seismic waves can be generated during a solar flare, several of which include a major role for accelerated electrons. To address this question further, we have selected two samples of white-light flares (WLFs): one that has associated sunquakes, and one that does not. We focus particularly on th…
Discovery of shocked H2 around OH 231.8+4.2
Forde, K. P.; Gledhill, T. M.
We present K-band integral field observations of the circumstellar envelope of the evolved star OH 231.8+4.2. Spatial and spectral information was simultaneously acquired using the SINFONI integral field unit, with adaptive optics, on the Very Large Telescope. The observations reveal the discovery of H2 emission (1) around the centre of…
CO prompt emission as a CO2 marker in comets and planetary atmospheres
Slanger, Tom G.; Kalogerakis, Konstantinos S.; Ahmed, Musahid +2 more
Observations of CO emissions in the visible and near-infrared (NIR) have been rare for comets, and no measurements from orbiters are currently available in the visible for the dayglows of Mars or Venus. Analysis of the ultraviolet CO(a-X) Cameron bands from Mars Express dayglow observations supports the conclusion that these bands have very high r…
Interstellar Gas in the Local Chimneys
Welsh, Barry Y.; Lallement, Rosine
We present ultraviolet absorption observations of four nearby (d < 250 pc) DA white dwarfs using spectral data (R ∼ 15 km s-1) obtained with the NASA HST Cosmic Origins Spectrograph (1150-1700 Å) and the Far Ultraviolet Spectroscopic Explorer (912-1170 Å). Two of these targets (WD2321 - 549 and WD2124 - 224) sample gas along the Sout…