Search Publications
The Spatio-Kinematical Structure and Distance of the Preplanetary Nebula IRAS 19134+2131
Sahai, Raghvendra; Morris, Mark; Imai, Hiroshi
Using the Very Long Baseline Array at six epochs, we have observed H2O maser emission in the preplanetary nebula IRAS 19134+2131 (I19134), in which the H2O maser spectrum has two groups of emission features separated in radial velocity by ~100 km s-1. We also obtained optical images of I19134 with the Hubble Space …
Spitzer Observations of Transient, Extended Dust in Two Elliptical Galaxies: New Evidence of Recent Feedback Energy Release in Galactic Cores
Brighenti, Fabrizio; Mathews, William G.; Temi, Pasquale
Spitzer observations of extended dust in two optically normal elliptical galaxies provide a new confirmation of buoyant feedback outflow in the hot gas atmospheres around these galaxies. AGN feedback energy is required to prevent wholesale cooling and star formation in these group-centered galaxies. In NGC 5044 we observe interstellar (presumably …
Tethys: Lithospheric thickness and heat flux from flexurally supported topography at Ithaca Chasma
Neukum, Gerhard; Thomas, Peter C.; Helfenstein, Paul +2 more
We have identified flexural uplift along the flanks of Tethys' Ithaca Chasma using Cassini stereo-derived topography. Modeling the topography as a broken elastic plate yields an effective elastic lithospheric thickness in the range of 5-7 km and, combined with the strength envelope of the lithosphere, a mechanical lithospheric thickness of 16-20 k…
Hard X-ray flares in IGR J08408-4503 unveil clumpy stellar winds
Masetti, N.; Walter, R.; Produit, N. +2 more
Context: A 1000-s flare from a new hard X-ray transient,
Magnetic Double-Gradient Instability and Flapping Waves in a Current Sheet
Semenov, V. S.; Erkaev, N. V.; Biernat, H. K.
A new kind of magnetohydrodynamic instability and waves are analyzed for a current sheet in the presence of a small normal magnetic field component varying along the sheet. These waves and instability are related to the existence of two gradients of the tangential (Bτ) and normal (Bn) magnetic field components along the norma…
Motion of flux transfer events: a test of the Cooling model
Dandouras, I.; Fazakerley, A. N.; Daly, P. W. +7 more
The simple model of reconnected field line motion developed by Cooling et al. (2001) has been used in several recent case studies to explain the motion of flux transfer events across the magnetopause. We examine 213 FTEs observed by all four Cluster spacecraft under a variety of IMF conditions between November 2002 and June 2003, when the spacecra…
Discovery of X-ray burst triplets in EXO 0748-676
Boirin, L.; Lewin, W. H. G.; in't Zand, J. J. M. +5 more
Type-I X-ray bursts are thermonuclear flashes that take place on the surface of accreting neutron stars. The wait time between consecutive bursts is set by the time required to accumulate the fuel needed to trigger a new burst; this is at least one hour. Sometimes secondary bursts are observed, approximately 10 min after the main burst. These shor…
Born-Again Protoplanetary Disk around Mira B
Lloyd, J. P.; Tuthill, P. G.; Packham, C. +6 more
The Mira AB system is a nearby (~107 pc) example of a wind accreting binary star system. In this class of system, the wind from a mass-losing red giant star (Mira A) is accreted onto a companion (Mira B), as indicated by an accretion shock signature in spectra at ultraviolet and X-ray wavelengths. Using novel imaging techniques, we report the dete…
Probing the Large-Scale Plasma Structure of the Solar Corona with Faraday Rotation Measurements
Spangler, Steven R.; Ingleby, Laura D.; Whiting, Catherine A.
Faraday rotation measurements of the solar corona made with the VLA at frequencies of 1465 and 1665 MHz are reported. The measurements were made along 20 lines of sight to 19 extragalactic radio sources in 2005 March and April. The closest heliocentric distances of the lines of sight ranged from 5.6 to 9.7 Rsolar. Measured rotation meas…
Braiding-induced Interchange Reconnection of the Magnetic Field and the Width of Solar Coronal Loops
Schrijver, Carolus J.
The random walk of the footpoints of coronal loops in the rapidly evolving solar granulation is expected to cause braiding of the field, which in turn should lead to a multitude of coronal reconnection events. Consequently, plasma volumes in coronal loops should repeatedly be spliced onto parts of other such loop structures within their lifetime i…