Search Publications
The Evolution of Galaxies in X-Ray-luminous Groups
Mulchaey, John S.; Fassnacht, Christopher D.; Lubin, Lori M. +1 more
We investigate the galaxy populations in seven X-ray-selected, intermediate-redshift groups (0.2<z<0.6). Overall, the galaxy populations in these systems are similar to those in clusters at the same redshift; they have large fractions of early-type galaxies (fe~70%) and small fractions of galaxies with significant star formation (…
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 …
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…
Observations Supporting the Role of Magnetoconvection in Energy Supply to the Quiescent Solar Atmosphere
Wilhelm, Klaus; McIntosh, Scott W.; Armstrong, James D. +4 more
Identifying the two physical mechanisms behind the production and sustenance of the quiescent solar corona and solar wind poses two of the outstanding problems in solar physics today. We present analysis of spectroscopic observations from the Solar and Heliospheric Observatory that are consistent with a single physical mechanism being responsible …
Local Helioseismology and Correlation Tracking Analysis of Surface Structures in Realistic Simulations of Solar Convection
Zhao, Junwei; Kosovichev, Alexander G.; Georgobiani, Dali +3 more
We apply time-distance helioseismology, local correlation tracking, and Fourier spatial-temporal filtering methods to realistic supergranule scale simulations of solar convection and compare the results with high-resolution observations from the Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager (MDI). Our objective is to investiga…
Deep XMM-Newton and Chandra Observations of Cl J1226.9+3332: A Detailed X-Ray Mass Analysis of a z = 0.89 Galaxy Cluster
Maughan, B. J.; Jones, L. R.; Jones, C. +1 more
Deep XMM-Newton and Chandra observations of Cl J1226.9+3332 at z=0.89 have enabled the most detailed X-ray mass analysis of any such high-redshift galaxy cluster. The XMM-Newton temperature profile of the system shows no sign of central cooling, with a hot core and a radially declining profile. A temperature map shows asymmetry with a hot region t…
XMM-Newton Observations Reveal the X-Ray Counterpart of the Very High Energy Gamma-Ray Source HESS J1640-465
Funk, S.; Reimer, O.; Hinton, J. A. +4 more
We present X-ray observations of the as of yet unidentified very high energy (VHE) γ-ray source HESS J1640-465 with the aim of establishing a counterpart of this source in the keV energy range, and identifying the mechanism responsible for the VHE emission. The 21.8 ks XMM-Newton observation of HESS J1640-465 in 2005 September represents a signifi…