Search Publications
Collapsed, uncollapsed, and hidden magnetic flux on the quiet Sun
Stenflo, J. O.
Since the first applications of the Stokes V line ratio in the early 1970s and the Hanle depolarization effect in the early 1980s we have had a dualistic view of quiet-Sun magnetism: intermittent kG flux tubes surrounded by an ocean of turbulent fields with strengths of order 10-100 G. There has been the concern that this dualism could be an artef…
Interaction between the intergalactic medium and central radio source in the NGC 4261 group of galaxies
Zezas, A.; Wolter, A.; Giacintucci, S. +4 more
Using observations from the Chandra and XMM-Newton X-ray observatories, we examine the interaction between the intragroup medium and central radio source in the nearby NGC 4261 galaxy group. We confirm the presence of cavities associated with the radio lobes and estimate their enthalpy to be ∼2.4 × 1058 erg. The mechanical power output …
Oxygen torus in the deep inner magnetosphere and its contribution to recurrent process of O+-rich ring current formation
Singer, H. J.; Takahashi, K.; Nosé, M. +1 more
Using the magnetic field and plasma wave data obtained by the Combined Release and Radiation Effects Satellite (CRRES), we search for enhancements of O+ ion density in the deep inner magnetosphere known as "the oxygen torus". We examine 4 events on the dayside in which toroidal standing Alfvén waves appear clearly. From the frequency of…
X-ray Emission from the Sombrero Galaxy: A Galactic-scale Outflow
Spitler, Lee R.; Jones, Christine; Gilfanov, Marat +8 more
Based on new and archival Chandra observations of the Sombrero galaxy (M 104 = NGC 4594), we study the X-ray emission from its nucleus and the extended X-ray emission in and around its massive stellar bulge. We find that the 0.3-8 keV luminosity of the nucleus appears constant at ~2.4 × 1040 erg s-1, or ~10-7 of it…
X-Ray Characteristics of NGC 3516: A View through the Complex Absorber
Turner, T. J.; Kraemer, S. B.; Reeves, J. N. +1 more
We consider new Suzaku data for NGC 3516 taken during 2009 along with other recent X-ray observations of the source. The cumulative characteristics of NGC 3516 cannot be explained without invoking changes in the line-of-sight absorption. Contrary to many other well-studied Seyfert galaxies, NGC 3516 does not show a positive lag of hard X-ray photo…
Temporal Variability of Active Region Outflows
Warren, Harry P.; Ugarte-Urra, Ignacio
Recent observations from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode have shown that low-density areas on the periphery of active regions are characterized by strong blueshifts in the emission of spectral lines formed at 1 MK. These Doppler shifts have been associated with outward propagating disturbances observed with extre…
On the anomalous secular increase of the eccentricity of the orbit of the Moon
Iorio, L.
A recent analysis of a Lunar Laser Ranging (LLR) data record spanning 38.7 yr revealed an anomalous increase of the eccentricity e of the lunar orbit amounting to ? yr-1. The present-day models of the dissipative phenomena occurring in the interiors of both the Earth and the Moon are not able to explain it. In this paper, we examine sev…
The effects of dust on the optical and infrared evolution of SN 2004et
Welch, D. L.; Barlow, M. J.; Clayton, Geoffrey C. +8 more
We present an analysis of multi-epoch observations of the Type II-P supernova SN 2004et. New and archival optical spectra of SN 2004et are used to study the evolution of the Hα and [O I] 6300-Å line profiles between days 259 and 646. Mid-infrared imaging with Michelle on Gemini-North and with all three instruments of the Spitzer Space Telescope wa…
Coronal Shock Waves, EUV Waves, and Their Relation to CMEs. III. Shock-Associated CME/EUV Wave in an Event with a Two-Component EUV Transient
Eselevich, M. V.; Eselevich, V. G.; Grechnev, V. V. +5 more
On 17 January 2010, STEREO-B observed in extreme ultraviolet (EUV) and white light a large-scale dome-shaped expanding coronal transient with perfectly connected off-limb and on-disk signatures. Veronig et al. (Astrophys. J. Lett.716, L57, 2010) concluded that the dome was formed by a weak shock wave. We have revealed two EUV components, one of wh…
HESS J1943+213: a candidate extreme BL Lacertae object
Klochkov, D.; Santangelo, A.; Quirrenbach, A. +199 more
Context. The H.E.S.S. Cherenkov telescope array has been surveying the Galactic plane for new VHE (>100 GeV) gamma-ray sources.
Aims: We report on a newly detected point-like source, HESS J1943+213. This source coincides with an unidentified hard X-ray source IGR J19443+2117, which was proposed to have radio and infrared counterparts.
…