Search Publications
Non-thermal Response of the Corona to the Magnetic Flux Dispersal in the Photosphere of a Decaying Active Region
Abramenko, V. I.; Harra, L. K.
We analyzed Solar Dynamics Observatory line-of-sight magnetograms for a decaying NOAA active region (AR) 11451 along with co-temporal Extreme-Ultraviolet Imaging Spectrometer (EIS) data from the Hinode spacecraft. The photosphere was studied via time variations of the turbulent magnetic diffusivity coefficient, η(t), and the magnetic power spectru…
Ultraviolet variability of the helium-peculiar star a Centauri
Sokolov, N. A.
The spectrophotometric variability of the classical magnetic chemically peculiar star a Cen in the ultraviolet spectral region from 1150 to 3100 Å is investigated. This study is based on archival International Ultraviolet Explorer data obtained at various phases of the rotational cycle. The light variations in wavelengths shorter than λ1616 Å are …
Pit distribution in the equatorial region of Titan
Adams, Kimberly A.; Jurdy, Donna M.
Cassini radar images of Titan's surface reveal numerous dark circular features in the equatorial region. These may be related to methane sublimation and have been interpreted as pits. In the T8 equatorial swath, we identify 199 individual pits and estimate their diameters. We analyze the observed spatial distribution and size to characterize these…
Running waves observed by Hinode
Liang, H. F.; Yang, W. G.; Ma, L. +1 more
High cadence (up to 9.6 s) intensity images of a sunspot within the active region NOAA 10953 were obtained by the SOT onboard Hinode with the line H α 6563 Å on April 30, 2007. The running difference images show that running waves periodically appear within the sunspot umbra and propagate outward forming full circles or partial arcs. The propagati…
Possible physical cause of the zonal wind collapse on Titan
Coustenis, Athena; Li, Jianping; Liu, Dong +1 more
A high-resolution vertical profile of Titan's winds was inferred from ground-based radiotelescopes, which recorded the Doppler Wind Experiment measurements of the carrier frequency during the Huygens mission (Bird et al., 2005). It indicates the existence of a wind shear layer with surprisingly low wind speed nearing zero, at altitudes between 60 …
On the soft X-ray emission of M82
Mao, S.; Wang, Q. D.; Liu, J.
We present a spatial analysis of the soft X-ray and Hα emissions from the outflow of the starburst galaxy M82. We find that the two emissions are tightly correlated on various scales. The O VII triplet of M82, as resolved by X-ray grating observations of XMM-Newton, is dominated by the forbidden line, inconsistent with the thermal prediction. The …
Precise modelling of solar and thermal accelerations on Rosetta
van der Ha, Jozef C.; Kato, Takahiro
This paper presents an analytical approach for the high-fidelity model of the accelerations induced by the Solar Radiation Pressure (SRP) and the Thermal Recoil Pressure (TRP) on ESA’s Rosetta spacecraft. The relevant gravitational forces that are induced by planets, moons, and asteroids can readily be incorporated for predicting interplanetary tr…
Null Variance Altitudes for the photolysis rate constants of species with barometric distribution: Illustration on Titan upper atmosphere modeling
Dobrijevic, Michel; Pernot, Pascal; Peng, Zhe +1 more
The precision of the rates of the photolysis processes initiating the complex chemistry of Titan's upper atmosphere conditions strongly the predictivity of photochemical models. Recent studies in sensitivity analysis of such models point out photolysis rate constants as key parameters. However, they have been treated approximately so far. We deal …
Expansion of the stellar subsystems of disk galaxies
Tikhonov, N. A.
Based on archival Hubble Space Telescope images, we have performed stellar photometry for eight edge-on spiral and irregular galaxies. We have identified stars with ages of 20, 50, 80, 160, and 500 Myr in the derived Hertzsprung-Russell diagrams and constructed their number density distributions perpendicularly to the plane of the galactic disk. W…
Observations of Electromagnetic Fluctuations at Ion Kinetic Scales in the Solar Wind
Podesta, John J.
Wavelet techniques enable reduced power spectra and cross-spectra to be analyzed as a function of the angle θ BV formed by the scale dependent local mean magnetic field B 0 and the flow direction of the solar wind. These techniques allow the data along a line oriented at any angle θ BV to B 0 to be iso…