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A Method for the Estimation of p-Mode Parameters from Averaged Solar Oscillation Power Spectra
Kosovichev, A. G.; Scherrer, P. H.; Larson, T. P. +3 more
A new fitting methodology is presented that is equally well suited for the estimation of low-, medium-, and high-degree mode parameters from m-averaged solar oscillation power spectra of widely differing spectral resolution. This method, which we call the “Windowed, MuLTiple-Peak, averaged-spectrum” or WMLTP Method, constructs a theoretical profil…
Investigation of the Geoeffectiveness of CMEs Associated with IP Type II Radio Bursts
Chen, Y.; Kong, X. L.; Wang, B. +1 more
We perform a statistical analysis of the geoeffectiveness of coronal mass ejections (CMEs) that are associated with interplanetary (IP) type II bursts in Solar Cycle 23 during the period 1997 - 2008. About 47 % (109 out of 232) of IP type II bursts are found to be associated with geomagnetic storms. Of these 47 %, 27 % are associated with moderate…
Solar Radius Variations: An Inquisitive Wavelength Dependence
Kilcik, Ali; Kosovichev, Alexander; Rozelot, Jean Pierre
Recent solar radius determinations from space observations of Mercury and Venus transits have been made by different teams in 2003, 2006, 2012, and 2014. Seemingly the results are not consistent: the authors interpreted the discrepancies as caused by the different methods of analysis. However, looking at the wavelength dependence and adding other …
Magnetic Flux Conservation in the Heliosheath Including Solar Cycle Variations of Magnetic Field Intensity
Tóth, G.; Richardson, J. D.; Opher, M. +2 more
In the heliosheath (HS), Voyager 2 has observed a flow with constant radial velocity and magnetic flux conservation. Voyager 1, however, has observed a decrease in the flow’s radial velocity and an order of magnitude decrease in magnetic flux. We investigate the role of the 11 yr solar cycle variation of the magnetic field strength on the magnetic…
An imaging and spectroscopic study of the planetary nebulae in NGC 5128 (Centaurus A). Planetary nebulae catalogues
Rejkuba, M.; Walsh, J. R.; Walton, N. A.
Context. Planetary nebulae (PNe) are excellent tracers of the common low mass stars through their strong and narrow emission lines. The velocities of large numbers of PNe are excellent tracers of galaxy kinematics. NGC 5128, the nearest large early-type galaxy, offers the possibility to gather a large sample.
Aims: Imaging and spectroscopic o…
Hall and finite Larmor radius effects on the dipolarization fronts associated with interchange instability
Zhang, T. L.; Nakamura, R.; Dunlop, M. W. +3 more
In this paper, we established a Hall-finite Larmor radius (FLR) MHD model by including Hall and finite Larmor radius (FLR) effects to study the dipolarization fronts (DFs) produced by the interchange instability in the magnetotail. The results indicate that the Hall effect on the scale of inertial length determines the distributions of electric fi…
Revealing a hard X-ray spectral component that reverberates within one light hour of the central supermassive black hole in Ark 564
Turner, T. J.; Kraemer, S. B.; Reeves, J. N. +4 more
Context. Arakelian 564 (Ark 564, z = 0.0247) is an X-ray-bright narrow-line Seyfert 1 galaxy. By using advanced X-ray timing techniques, an excess of "delayed" emission in the hard X-ray band (4-7.5 keV) following about 1000 s after "flaring" light in the soft X-ray band (0.4 - 1 keV) was recently detected.
Aims: We report on the X-ray spectr…
Remnant buried ice in the equatorial regions of Mars: Morphological indicators associated with the Arsia Mons tropical mountain glacier deposits
Head, James W.; Marchant, David R.; Scanlon, Kathleen E.
The fan-shaped deposit (FSD) on the western and northwestern flanks of Arsia Mons is the remnant of tropical mountain glaciers, deposited several tens to hundreds of millions of years ago during periods of high spin-axis obliquity. Previous workers have argued that the Smooth Facies in the FSD contains a core of ancient glacial ice. Here, we find …
Compensated-current instability of kinetic Alfvén waves
De Keyser, J.; Malovichko, P.; Voitenko, Y.
We study a non-resonant instability of kinetic Alfvén waves (KAWs) driven by compensated currents. Such currents set up in response to energetic ion beams occurring in many space and astrophysical plasmas, like foreshock regions in the solar wind and around supernova remnants. Kinetic effects of the background ion gyroradius make the KAW instabili…
Core Shapes and Orientations of Core-Sérsic Galaxies
Graham, Alister W.; Dullo, Bililign T.
The inner and outer shapes and orientations of core-Sérsic galaxies may hold important clues to their formation and evolution. We have therefore measured the central and outer ellipticities and position angles for a sample of 24 core-Sérsic galaxies using archival Hubble Space Telescope (HST) images and data. By selecting galaxies with core-Sérsic…