Search Publications
Radio Observations of Rapid Acceleration in a Slow Filament Eruption/Fast Coronal Mass Ejection Event
Janardhan, P.; Kundu, M. R.; White, S. M. +4 more
We discuss a filament eruption/coronal mass ejection (CME) event associated with a flare of GOES class M2.8 that occurred on 2001 November 17. This event was observed by the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz. NoRH observed the filament during its eruption both as a dark feature against the solar disk and a bright feature above the …
On Collisionless Electron-Ion Temperature Equilibration in the Fast Solar Wind
Laming, J. Martin
We explore a mechanism, entirely new to the fast solar wind, of electron heating by lower hybrid waves to explain the shift to higher charge states observed in various elements in the fast wind at 1 AU relative to the original coronal hole plasma. This process is a variation on that previously discussed for two-temperature accretion flows by Begel…
Interplanetary Transport Mechanisms of Solar Energetic Particles
Zhang, M.; Qin, G.; Dwyer, J. R. +1 more
Numerical simulations of charged particle trajectories in a Parker field with model turbulence are used to study the transport mechanisms of solar energetic particles (SEPs): magnetic focusing, pitch-angle diffusive transport due to magnetic fluctuations, and adiabatic cooling. The results of the simulations are compared with analytical formulae f…
Accuracy of the Born and Ray Approximations for Time-Distance Helioseismology of Flows
Birch, A. C.; Felder, G.
Time-distance helioseismology has been used extensively to study mass flows (for example, flows associated with supergranulation), active regions, and sunspots. In nearly all of these studies the sensitivity of travel times to subsurface flows has been modeled using the first-order ray approximation. The Born approximation has been proposed as a m…
Supersoft X-Ray Sources in M31. II. ROSAT-detected Supersoft Sources in the ROSAT, Chandra, and XMM-Newton Eras
Greiner, J.; Primini, F.; Di Stefano, R. +1 more
We have performed Chandra observations during the past three years of five of the M31 supersoft X-ray sources discovered with ROSAT. Surprisingly, only one of these sources has been detected, despite a predicted detection of about 20-80 counts for these sources. This has motivated a thorough check of the ROSAT M31 Survey I data, including a relaxa…
PV Cephei: Young Star Caught Speeding?
Arce, Héctor G.; Goodman, Alyssa A.
Three independent lines of evidence imply that the young star PV Cep is moving at roughly 20 km s-1 through the interstellar medium. The first and strongest suggestion of motion comes from the geometry of the Herbig-Haro (HH) knots in the ``giant'' HH flow associated with PV Cep. Bisectors of lines drawn between pairs of knots at nearly…
Low-Mass Pre-Main-Sequence Stars in the Large Magellanic Cloud. III. Accretion Rates from Hubble Space Telescope WFPC2 Observations
Panagia, N.; Robberto, M.; Romaniello, M.
We have measured the present accretion rate of roughly 800 low-mass (~1-1.4 Msolar) pre-main-sequence stars in the field of supernova 1987A in the Large Magellanic Cloud (Z~=0.3 Zsolar). It is the first time that this fundamental parameter for star formation has been determined for low-mass stars outside our Galaxy. The Balme…
Self-Gravitating Eccentric Disk Models for the Double Nucleus of M31
Statler, Thomas S.; Salow, Robert M.
We present new dynamical models of weakly self-gravitating, finite dispersion eccentric stellar disks around central black holes for the double nucleus of M31. The disk is fixed in a frame rotating at constant precession speed and is populated by stars on quasi-periodic orbits whose parents are numerically integrated periodic orbits in the total p…
Spatially Resolved Ultraviolet Spectra of the High-Velocity Nuclear Outflow of NGC 1068
Ferruit, Pierre; Dopita, Michael A.; Cecil, Gerald +1 more
We present ultraviolet emission-line maps of the narrow-line region (NLR) of NGC 1068. The maps span 115-318 nm, the biconical ionization cone, and several posited jet-ISM interactions, and the compact knots whose optical spectra we reported previously resemble kinematically the quasar associated absorption line systems. Across the NLR, we find th…
Time-resolved Ultraviolet Spectroscopy of the SW Sex Star DW UMa: Confirmation of a Hidden White Dwarf and the Ultraviolet Counterpart to Phase 0.5 Absorption Events
Dhillon, V. S.; Szkody, Paula; Hoard, D. W. +5 more
We present time-resolved ultraviolet (UV) spectroscopy of the SW Sex star DW UMa in the high state. We confirm that shortward of 1500 Å, the high-state UV continuum level is lower than the white dwarf (WD) dominated low-state level. We also do not see the WD contact phases in the high-state eclipse light curves. These results confirm our earlier f…