Search Publications
Solar and Galactic Cosmic Rays Observed by SOHO
Curdt, W.; Fleck, B.
Both the Cosmic Ray Flux (CRF) and Solar Energetic Particles (SEPs) have left an imprint on SOHO technical systems. While the solar array efficiency degraded irreversibly down to ≈77% of its original level over roughly 1 1/2 solar cycles, Single Event Upsets (SEUs) in the solid state recorder (SSR) have been reversed by the memory protection mecha…
The Hot--blackbody Spectral Excess in Low--luminosity High--Mass X--Ray Binaries
Tiengo, A.; Mereghetti, S.; Sidoli, L. +2 more
We report on the main results obtained thanks to an observation campaign with XMM-Newton of four persistent, low-luminosity (L_{X} ∼ 10^{34} erg s^{-1}) and long-period (P > 200 s) Be accreting pulsars. We found that all sources considered here are characterized by a spectral excess that can be described with a blackbody component of high tempe…
Simultaneous Analysis of Recurrent Jovian Electron Increases and Galactic Cosmic Ray Decreases
Fichtner, H.; Scherer, K.; Gómez-Herrero, R. +10 more
The transport environment for particles in the heliosphere, e.g. galactic cosmic rays (GCRs) and MeV electrons (including those originating from Jupiters magnetosphere), is defined by the solar wind flow and the structure of the embedded heliospheric magnetic field. Solar wind structures, such as co-rotating interaction regions (CIR), can result i…
Results of the Recent \varepsilon Aurigae Eclipse Campaign
Stencel, R. E.
Results of the 2010 eclipse campaign are described, and preliminary interpretations proposed. These include photometric, interferometric, spectroscopic, astrometric and polarimetric observational results. Next steps, along with continued monitoring, include simulations and other future work. Numerous acknowledgements are appropriate for the many p…
UV Radiation of the Young Sun and its Implications for Life in the Solar System
Buccino, A. P.; Mauas, P. J. D.; Hanslmeier, A. +3 more
UV radiation is thought to have played an important role in the origin of life on Earth. To estimate these levels of UV radiation, we computed the UVC fluxes from HST/STIS and IUE spectra of the young solar analogs κ^1 Cet and χ^1 Ori. In the future experiments with extremophilic microorganisms we will use these resulting UVC-levels to test the pr…
Study of CME Properties Using High Resolution Data
Fainshtein, V. G.; Egorov, Ya. I.
The joint use of high-resolution data from SDO and PROBA2 satellites and LASCO/SOHO coronographs enabled us to examine early stages of initiation and propagation of six limb CMEs registered in June 2010 - June 2011. For five events under consideration, the CME initiation is marked by filament (prominence) eruption or by a loop-like structure havin…
Observations of the Unique X--ray Emitting Subdwarf Stars HD 49798 and BD +37° 442
Tiengo, A.; Mereghetti, S.; Stella, L. +3 more
We report on the results we obtained with XMM observations of HD 49798 and BD +37° 442, the only two sdO stars for which X-ray emission has been observed so far. HD 49798 is a single-lined spectroscopic binary with orbital period of 1.5 days. We could establish that its companion is a massive white dwarf with M = 1.28 M_{⊙}, which makes it a candi…
Searching for Pulsating Stars in Eclipsing Binaries in the OMC--VAR Catalogue
Montesinos, B.; Mas-Hesse, J. M.; Moya, A. +2 more
The first catalogue of variable sources observed by OMC (OMC--VAR hereafter) contains light curves for 5263 variable stars, out of which we have been able to detect periodicities for 1137 objects. A large variety of objects can be found in the catalogue, but the most frequent ones in the present compilation are pulsating stars and eclipsing binari…
Triangulation of CME Source Region Locations on the Sun and Dependence on Spacecraft Observation Angles
Temmer, M.; Hanslmeier, A.; Preiss, S.
STEREO-A, STEREO-B, and LASCO/SOHO observe coronal mass ejections (CMEs) from three different vantage points. On the basis of the radial plane-of-sky (POS) measurements of a CME in these three projection planes, the CME source region (SR) location was determined using the triangulation method of Temmeretal2009. As this triangulation method needs d…
Constraining Electron Acceleration at a Standing Shock with HXR and Radio Observations
Mann, G.; Aurass, H.; Warmuth, A.
The acceleration of electrons to non-thermal energies in solar flares is one of the main unsolved questions in solar physics. One possibility for the production of these energetic electrons is acceleration at the reconnection outflow termination shock (TS). We use radio observations to constrain the characteristics of the TS, and hard X-ray and γ-…