Search Publications
On the relation between asymmetries in the ring current and magnetopause current
Haaland, S.; Gjerloev, J.
Motion of charged particles in the Earth's magnetosphere sets up a system of currents. Current continuity requires that these currents are closed, either locally or via other current systems. In this paper, we have investigated whether magnetopause surface currents can contribute to ring current closure. Using measurements from the Cluster constel…
A 1-D model of physical chemistry in Saturn's inner magnetosphere
Delamere, P. A.; Bagenal, F.; Fleshman, B. L. +1 more
Water vapor spewed out of Enceladus' geysers spreads across the Saturn system through dissociation, charge exchange, and neutral-neutral collisions. The combined effects of impact ionization by suprathermal electrons, charge-exchange between ions and neutrals, and radial transport of the plasma produce the observed distribution of ions and their t…
Optical and X-ray properties of CAL 83 - I. Quasi-periodic optical and supersoft variability
Udalski, A.; Charles, P. A.; Meintjes, P. J. +2 more
We have studied the long-term (∼ years) temporal variability of the prototype supersoft X-ray source (SSS) CAL 83 in the Large Magellanic Cloud, using data from the massive compact halo object (MACHO) and Optical Gravitational Lensing Experiment (OGLE) projects. The CAL 83 light curve exhibits dramatic brightness changes of ∼1 mag on time-scales o…
The Extended Solar Cycle Tracked High into the Corona
Tappin, S. J.; Altrock, R. C.
We present observations of the extended solar cycle activity in white-light coronagraphs, and compare them with the more familiar features seen in the Fe XIV green-line corona. We show that the coronal activity zones seen in the emission corona can be tracked high into the corona. The peak latitude of the activity, which occurs near solar maximum,…
The Discovery of Pulsating Hot Subdwarfs in NGC 2808
Brown, Thomas M.; Sweigart, Allen V.; Landsman, Wayne B. +2 more
We present the results of a Hubble Space Telescope program to search for pulsating hot subdwarfs in the core of NGC 2808. These observations were motivated by the recent discovery of such stars in the outskirts of ω Cen. Both NGC 2808 and ω Cen are massive globular clusters exhibiting complex stellar populations and large numbers of extreme horizo…
Variability in ionospheric total electron content at Mars
Withers, Paul; Kofman, Wlodek; Mendillo, Michael +3 more
The Mars Express (MEX) mission includes a multi-purpose radio instrument called the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS). When used in its ionospheric-penetrating subsurface sounder (SS) radar mode, a by-product of the MARSIS observations is the ray-path-integral of electron densities, called the total electron cont…
Utility of laser altimeter and stereoscopic terrain models: Application to Martian craters
Hynek, Brian M.; Robbins, Stuart J.
The use of numerical datasets of the same type derived from remote sensing instruments is often treated as equivalent in value and utility, within the limits of their spatial resolution. Surface topography is a good example of this. We used gridded digital terrain models (DTMs) derived from both laser altimetry and stereo pairs as well as the orig…
The orientation dependence of quasar spectral energy distributions
Brotherton, M. S.; Runnoe, Jessie C.; Shang, Z.
We investigate the orientation dependence of the spectral energy distributions in a sample of radio-loud quasars. Selected specifically to study orientation issues, the sample contains 52 sources with redshifts in the range 0.16 < z < 1.4 and measurements of radio core dominance, a radio orientation indicator. Measured properties include mon…
Probing the Cosmic X-Ray and MeV Gamma-Ray Background Radiation through the Anisotropy
Uchiyama, Yasunobu; Inoue, Yoshiyuki; Murase, Kohta +1 more
While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal…
Mining unusual and rare stellar spectra from large spectroscopic survey data sets using the outlier-detection method
Liu, Jie; Kong, Xiao; Li, Yinbi +9 more
The large number of spectra obtained from sky surveys such as the Sloan Digital Sky Survey (SDSS) and the survey executed by the Large sky Area Multi-Object fibre Spectroscopic Telescope (LAMOST, also called GuoShouJing Telescope) provide us with opportunities to search for peculiar or even unknown types of spectra. In response to the limitations …