Search Publications
Solar Wind Outflow in Polar Plumes from 1.05 to 2.4 Rsolar
Llebaria, A.; Abbo, L.; Antonucci, E. +2 more
An earlier publication (Paper I), which measured the outflow velocity in solar plumes out to 1.35 Rsolar using the Doppler dimming technique, has here been extended out to 2.4 Rsolar by including observations from SOHO UVCS. It is shown that plume outflow velocities, greater than interplumes at lower heights, have lower accel…
X-Ray Emission and Optical Polarization of V1432 Aquilae: An Asynchronous Polar
Singh, K. P.; Buckley, D. A. H.; Rana, V. R. +1 more
A detailed analysis of X-ray data obtained with ROSAT, ASCA, XMM-Newton, and the Rossi X-ray Timing Explorer (RXTE) for the asynchronous polar V1432 Aquilae is presented. An analysis of Stokes polarimetry data obtained from the South African Astronomical Observatory (SAAO) is also presented. Power spectra from long-baseline ROSAT data show a spin …
A Survey of Analogs to Weak Mg II Absorbers in the Present
Charlton, Jane C.; Narayanan, Anand; Lynch, Ryan +1 more
We present the results of a survey of the analogs of weak Mg II absorbers [rest-frame equivalent width Wr(2796)<0.3 Å] at 0<z<0.3. Our sample consisted of 25 HST STIS echelle quasar spectra (R=45,000), which covered Si II λ1260 and C II λ1335 over this redshift range. Using those similar transitions as tracers of Mg II facilita…
Multiwavelength Analysis of a Solar Flare on 2002 April 15
White, Stephen M.; Zhang, Jie; Holman, Gordon D. +1 more
We carried out a multiwavelength analysis of the solar limb flare on 2002 April 15. The observations all indicate that the flare occurred in an active region with an asymmetric dipole magnetic configuration. The earlier conclusion that magnetic reconnection is occurring in a large-scale current sheet in this flare is further supported by these obs…
Near-Infrared, Kilosecond Variability of the Wisps and Jet in the Crab Pulsar Wind Nebula
Romani, R. W.; Eikenberry, S. S.; Rigaut, F. +6 more
We present a time-lapse sequence of 20 near-infrared (J and K' band) snapshots of the central 20×20 of the Crab pulsar wind nebula, taken at subarcsecond resolution with the Hokupa`a/QUIRC adaptive optics camera on the Gemini North Telescope and sampled at intervals of 10 minutes and 24 hr. It is observed that the equatorial wisps and polar knots …
In Search of the Solar Cycle Variations of p-Mode Frequencies Generated by Perturbations in the Solar Interior
Chou, Dean-Yi; Serebryanskiy, Alexander
Observations show that the solar p-mode frequencies change with the solar cycle. The horizontal phase velocity dependence of the relative frequency change, scaled by mode mass, provides depth information on the perturbation in the solar interior. Our model study suggests that variations of smoothed, scaled relative frequency change versus horizont…
O/H in the Local Bubble
Chayer, Pierre; Dupuis, Jean; Oliveira, Cristina M. +1 more
We present new measurements of the oxygen gas-phase abundance along four sight lines probing gas inside the Local Bubble, using data obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telescope (HST). Combining these with seven previously published N(O I) and N(H I) measurements, we determine a mean O/H ratio for …
The Far-Ultraviolet Spectrum of Z Camelopardalis in Quiescence and Standstill
Long, Knox S.; Drew, Janet E.; Froning, Cynthia S. +1 more
We have obtained FUSE (905-1187 Å) spectra of the nonmagnetic cataclysmic variable Z Cam during a period of quiescence. The spectrum resembles that of a hot (57,000 K) metal-enriched white dwarf. A high effective temperature is consistent with the expectation that dwarf nova systems that show standstills, as Z Cam does, have higher than normal tim…
Transition Region Downflows in the Impulsive Phase of Solar Flares
Brooks, D. H.; Kurokawa, H.; Kamio, S. +2 more
We present observations of four flares that occurred during coordinated observations between the Coronal Diagnostic Spectrometer (CDS) on board SOHO and the Domeless Solar Telescope (DST) at Hida Observatory. We studied the evolution of relative Doppler velocities in the flare kernels by using He I (3.5×104 K), O V (2.2×105 K…
Observations of Hα Intensity Oscillations in a Flare Ribbon
Gallagher, Peter T.; Mathioudakis, Mihalis; Bloomfield, D. Shaun +6 more
High-cadence Hα blue wing observations of a C9.6 solar flare obtained at Big Bear Solar Observatory using the Rapid Dual Imager are presented. Wavelet and time-distance methods were used to study oscillatory power along the ribbon, finding periods of 40-80 s during the impulsive phase of the flare. A parametric study found statistically significan…