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Cross helicity at the solar surface by simulations and observations
Küker, M.; Schnerr, R. S.; Rüdiger, G.
A result of the quasilinear mean-field theory for driven magnetohydrodynamic (MHD) turbulence is that the observed cross helicity ⟨u·b⟩ may directly yield the magnetic eddy diffusivity ηT of the quiet Sun. In order to model the cross helicity at the solar surface, magnetoconvection under the presence of a vertical large-scale magnetic f…
Observations of the Interaction of Acoustic Waves and Small-scale Magnetic Fields in a Quiet Sun
Kariyappa, R.; Chitta, Lakshmi Pradeep; Jefferies, Stuart M. +1 more
The effect of the magnetic field on photospheric intensity and velocity oscillations at the sites of small-scale magnetic fields (SMFs) in a quiet Sun near the solar disk center is studied. We use observations made by the G-band filter in the Solar Optical Telescope on board Hinode for intensity oscillations; Doppler velocity, magnetic field, and …
Coronal Diagnostics from Narrowband Images Around 30.4 nm
Andretta, V.; Del Zanna, G.; Telloni, D.
Images taken in the band centered at 30.4 nm are routinely used to map the radiance of the He II Ly α line on the solar disk. That line is one of the strongest, if not the strongest, line in the EUV observed in the solar spectrum, and one of the few lines in that wavelength range providing information on the upper chromosphere or lower transition …
The orientation and current density of the magnetotail current sheet: A statistical study of the effect of geomagnetic conditions
Lester, M.; Milan, S. E.; Fear, R. C. +2 more
We examine the orientation and current density of the current sheet during current sheet crossings from Cluster's 2001-2007 tail seasons. The curlometer technique is used to estimate the current density and is combined with Minimum Variance Analysis (MVA) to calculate the direction of the current sheet normal. The SYM-H and AE indices at the time …
On the Detectability of a Predicted Mesolensing Event Associated with the High Proper Motion Star VB 10
Lépine, Sébastien; DiStefano, Rosanne
Extrapolation of the astrometric motion of the nearby low-mass star VB 10 indicates that sometime in late 2011 December or during the first 2-3 months of 2012, the star will make a close approach to a background point source. Based on astrometric uncertainties, we estimate a 1 in 2 chance that the distance of closest approach ρmin will …
Analysis and Modeling of Two Flare Loops Observed by AIA and EIS
Ding, M. D.; Li, Y.; Qiu, J.
We analyze and model an M1.0 flare observed by SDO/AIA and Hinode/EIS to investigate how flare loops are heated and evolve subsequently. The flare is composed of two distinctive loop systems observed in extreme ultraviolet (EUV) images. The UV 1600 Å emission at the feet of these loops exhibits a rapid rise, followed by enhanced emission in differ…
Hydrocode simulations of the largest crater on asteroid Lutetia
Cremonese, G.; Marzari, F.; Preusker, F. +9 more
The flyby of the Main Belt asteroid Lutetia by the Rosetta spacecraft allows the camera OSIRIS to obtain very good images of about half of the body at the maximum resolution of 60 m per pixel. From the images and radio-science experiment, a density of about (3.4±0.3) g/cm3 has been inferred for the asteroid. Many impact craters have bee…
The solar hydrogen Lyman α to Lyman β line ratio
Vial, J. -C.; Curdt, W.; Schühle, U. +2 more
Aims: We investigate the variation in the solar hydrogen Lyman α (Lyα) to Lyman β (Lyβ) line ratio as a function of the solar activity by taking into account new results obtained by SoHO/SUMER and TIMED/SEE.
Methods: We reanalyze data of quiet and active regions previously collected with the LPSP multichannel instrument on OSO8. We then …
The peculiar isolated neutron star in the Carina Nebula. Deep XMM-Newton and ESO-VLT observations of 2XMM J104608.7-594306
Motch, C.; Treves, A.; Pilia, M. +5 more
While fewer in number than the dominant rotation-powered radio pulsar population, peculiar classes of isolated neutron stars (INSs) - which include magnetars, the ROSAT-discovered "Magnificent Seven" (M7), rotating radio transients (RRATs), and central compact objects in supernova remnants (CCOs) - represent a key element in understanding the neut…
Ionized X-ray reverberation mapping: testing a light-bending model for 1H0707-495
Chainakun, P.; Young, A. J.
The narrow-line Seyfert 1 galaxy 1H0707-495 has shown the first clear evidence of X-ray reverberation in which the soft, disc-reflection and Fe-L-dominated 0.3-1 keV band lags behind the hard, continuum-dominated 1-4 keV band by ≈ 30 s. A simple reflection model, however, cannot explain the different amplitudes of variability between the continuum…