Search Publications
Observational Evidence for a Double-Helix Structure in CMEs and Magnetic Clouds
Osherovich, Vladimir; Fainberg, Joseph; Webb, Alla
We compare recent observations of a solar eruptive prominence as seen in extreme-UV light on 30 March 2010 by the Solar Dynamics Observatory (SDO) with the multi-tube model for interplanetary magnetic clouds (Osherovich, Fainberg, Stone, Geophys. Res. Lett.26, 2597, 1999). Our model is based on an exact analytical solution of the plasma equilibriu…
Prominence Cavity Regions Observed Using SWAP 174 Å Filtergrams and Simultaneous Eclipse Flash Spectra
Koutchmy, S.; Tavabi, E.; Bazin, C.
SWAP images from PROBA2 taken at 174 Å in the Fe IX/X lines are compared with simultaneous slitless flash spectra obtained during the solar total eclipse of 11 July 2010. Myriad faint low-excitation emission lines together with the He I and He II Paschen α chromospheric lines are recorded on eclipse spectra where regions of limb prominences are ob…
Detection of Solar Rotational Variability in the Large Yield RAdiometer (LYRA) 190 - 222 nm Spectral Band
Schmutz, W.; Rozanov, E.; Shapiro, A. I. +4 more
We analyze the variability of the spectral solar irradiance during the period from 7 January 2010 until 20 January 2010 as measured by the Herzberg channel (190 - 222 nm) of the Large Yield RAdiometer (LYRA) onboard PROBA2. In this period of time, observations by the LYRA nominal unit experienced degradation and the signal produced by the Herzberg…
Solar Activity and Deep Convection Modeling
Khodachenko, M. L.; Arkhypov, O. V.; Antonov, O. V.
We suggest from synoptic charts of radial magnetic field and intensities of spectral lines (Fe I, He II, and Fe IX/X) over Carrington rotations 1942 - 2050 that deep convective layers control the pattern of large-scale solar activity. A new result is a Kolmogorov-type energy spectrum of the longitudinal variations of solar activity. This spectrum …
Neutral and Ionized Hydrides in Star-Forming Regions. Observations with Herschel/HIFI
van Dishoeck, Ewine F.; Benz, Arnold O.; Wampfler, Susanne F. +2 more
The cosmic abundance of hydrides depends critically on high-energy UV, X-ray, and particle irradiation. Here we study hydrides in star-forming regions where irradiation by the young stellar object can be substantial, and density and temperature can be much enhanced over interstellar values. Lines of OH, CH, NH, and SH and their ions OH+, CH+, NH+,…
XMM-Newton Observations of the TeV γ-Ray Source HESS J1804-216
Lin, Dacheng; Webb, Natalie A.; Barret, Didier
We have analyzed three XMM-Newton observations of the central part of the unidentified TeV γ-ray source HESS J1804-216. We focus on two X-ray sources, 2XMMi J180442.0-214221 (Src 1) and 2XMMi J180432.5-214009 (Src 2), which were suggested to be the possible X-ray counterparts to the TeV source. We discover a 2.93 hr X-ray periodicity from Src 1, w…
Testing Dvali-Gabadadze-Porrati gravity with Planck
Xia, Jun-Qing; Li, Hong
Recently, the Planck Collaboration has released the first cosmological papers providing the highest resolution, full sky, maps of the cosmic microwave background (CMB) temperature anisotropies. It is crucial to understand that whether the accelerating expansion of our universe at present is driven by an unknown energy component (Dark Energy) or a …
Outflows and Dark Bands at Arcade-like Active Region Core Boundaries
Martens, P. C. H.; Scott, J. T.; Tarr, L.
Observations from the EUV Imaging Spectrometer (EIS) on board Hinode have revealed outflows and non-thermal line broadening in low intensity regions at the edges of active regions (ARs). We use data from Hinode's EIS, Solar Dynamic Observatory's Atmospheric Imaging Assembly and Helioseismic and Magnetic Imager, and the Transition Region and Corona…
Observational aspects of IMF draping-related magnetosheath accelerations for northward IMF
Farrugia, C. J.; Erkaev, N. V.; Harris, B. +1 more
Acceleration of magnetosheath plasma resulting from the draping of the interplanetary magnetic field (IMF) around the magnetosphere can give rise to flow speeds that exceed that of the solar wind (VSW) by up to ~60%. Three case event studies out of 34 identified events are described. We then present a statistical study of draping-relate…
Peculiarities and Variations in the Optical Spectrum of the RV Tauri-type Star R Sct
Kipper, Tõnu; Klochkova, Valentina G.
We analyzed some new high resolution optical spectra of the semiregular RV Tauri-type star R Sct. Fundamental parameters were found to be Teff=4500 K, log g=0.0 and ξt=4.0 km s-1. The results of chemical analysis show that R Sct is a metal-poor star with [Fe/H]≈-0.5. The carbon content with respect to iron is signi…