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Local helioseismology and the active Sun

Schunker, H.

The goal of local helioseismology is to elicit three-dimensional information about the sub-surface (or far-side) structure and dynamics of the Sun from observations of the helioseismic wave field at the surface. The physical quantities of interest include flows, sound-speed deviations and magnetic fields. However, strong surface magnetic fields in…

Determination of a precise rotation period for the Deep Space 1 target, Comet 19P/Borrelly

Samarasinha, Nalin H.; Rauer, Heike; Helbert, Jörn +1 more

The rotation period derived by Mueller and Samarasinha (Mueller, B.E.A., Samarasinha, N.H. [2002]. Earth Moon Planets 90, 463-471) of the Deep Space 1 (DS1) mission target, Comet 19P/Borrelly, using ground-based data from July 28 to August 1, 2000, is improved by two orders of magnitude. This precision is reached in a multistep process. Combining …

Trajectory and atmospheric structure from entry probes: Demonstration of a real-time reconstruction technique using a simple direct-to-Earth radio link

Withers, Paul

The reconstruction of the trajectory and atmospheric structure associated with an entry probe has traditionally relied upon onboard accelerometer measurements. Here we outline an equivalent reconstruction technique that uses Doppler-shifted direct-to-Earth transmissions instead. A critical assumption is that the entry probe's angle of attack is ze…

Assessment of Stellar Stratification in Three Young Star Clusters in the Large Magellanic Cloud

Gouliermis, Dimitrios A.; Mackey, Dougal; Rochau, Boyke +1 more

We present a comprehensive study of stellar stratification in young star clusters in the Large Magellanic Cloud (LMC). We apply our recently developed effective radius method for the assessment of stellar stratification on imaging data obtained with the Advanced Camera for Surveys of three young LMC clusters to characterize the phenomenon and deve…

Properties of the Variation of the Infrared Emission of Oh/ir Stars II. The L Band Light Curves

Suh, Kyung-Won; Kwon, Young-Joo

XMM-Newton observations of the hot spot galaxy NGC 2903

Ebrero, J.; Pérez-Ramírez, D.; Leon, S. +1 more

We report on the first deeper X-ray broad-band observation of the hot spot galaxy NGC 2903 obtained with XMM-Newton. X-ray imaging and spectra of the spiral barred galaxy NGC 2903 were obtained from XMM-Newton archival data to study its X-ray population and the conditions of the hot gas in its central region. We investigate the spectral properties…

Multi-strand Coronal Loop Model and Filter-ratio Analysis

Marsch, Eckart; Bourouaine, Sofiane

We model a coronal loop as a bundle of seven separate strands or filaments. Each of the loop strands used in this model can independently be heated (near their left footpoints) by Alfvén/ion-cyclotron waves via wave-particle interactions. The Alfvén waves are assumed to penetrate the strands from their footpoints, at which we consider different wa…

Physical Conditions in Orion's Veil. III. UV Iron Absorption Lines toward θ¹B Orionis

Abel, N.; Lykins, M. L.; Troland, T. H.

We have used archival Space Telescope Imaging Spectrograph (STIS) data in the range 2100-2500 Å toward the Trapezium star Θ¹ B Orionis (HD 37021) to estimate the Fe column density and other parameters in the neutral Veil of Orion. The Veil lies 1-3 pc in front of the Orion H⁺ region, it has an estimated volume density of 10

Blasts and shocks in the disc of NGC 4258

Battaner, E.; Mediavilla, E.; Castillo-Morales, A. +1 more

We present integral field spectroscopic observations of the central region of the active galaxy NGC 4258 obtained with the fibre IFU system INTEGRAL. We have been able to detect cold neutral gas by means of the interstellar NaD doublet absorption and to trace its distribution and kinematics with respect to the underlying disc. The neutral gas is b…

Independent Signals from the Influence of Internal Magnetic Layers on the Frequencies of Solar p-modes

Foullon, C.; Nakariakov, V. M.

The discovery that p-mode frequencies of low degree do not follow changes of solar surface activity during the recent solar minimum offers the possibility of a new diagnostic signature of the responsible pressure perturbation in the wave guiding medium, potentially rich of information regarding the structure of the Sun and the cause of the unusual…