Search Publications
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…
Virgo's Intracluster Globular Clusters as Seen by the Advanced Camera for Surveys
Ferguson, Henry C.; Williams, Benjamin F.; Freeman, Ken C. +11 more
We report the discovery of four candidate intracluster globular clusters (IGCs) in a single deep HST ACS field of the Virgo Cluster. We show that each cluster is roughly spherical, has a magnitude near the peak of the Virgo globular cluster luminosity function, has a radial profile that is best fitted by a King model, and is surrounded by an exces…
Surface Brightness Fluctuations from Archival ACS Images: A Stellar Population and Distance Study
Blakeslee, John; Cantiello, Michele; Raimondo, Gabriella +2 more
We derive surface brightness fluctuations (SBF) and integrated magnitudes in the V and I bands using Advanced Camera for Surveys (ACS) archival data. The sample includes 14 galaxies covering a wide range of physical properties: morphology, total absolute magnitude, and integrated color. We take advantage of the latter characteristic of the sample …
Bimodal Infrared Colors of the M87 Globular Cluster System: Peaks in the Metallicity Distribution
Kundu, Arunav; Zepf, Stephen E.
The globular cluster (GC) systems of many galaxies reveal bimodal optical color distributions. Based on stellar evolutionary models and the bimodal colors and metallicities of Galactic GCs, this is thought to reflect an underlying bimodal metallicity distribution. However, stars at many different phases of stellar evolution contribute to optical l…
The Magnetar Nature and the Outburst Mechanism of a Transient Anomalous X-Ray Pulsar
Kouveliotou, Chryssa; Göǧüş, Ersin; Güver, Tolga +1 more
Anomalous X-ray pulsars (AXPs) belong to a class of neutron stars believed to harbor the strongest magnetic fields in the universe, as indicated by their energetic bursts and their rapid spin-downs. However, an unambiguous measurement of their surface field strengths has not been made to date. It is also not known whether AXP outbursts result from…
Hubble Space Telescope and Spitzer Observations of the Afterglow and Host Galaxy of GRB 050904 at z = 6.295
Gladders, M. D.; Cenko, S. B.; Peterson, B. A. +11 more
We present deep Hubble Space Telescope (HST) and Spitzer Space Telescope observations of GRB 050904 at z=6.295. We detect the afterglow in the H band more than 3 weeks after the burst and confirm the presence of a jet break at t~2.1 days. This leads to an estimated opening angle of about 4° and a beaming-corrected energy of about 1051 e…
The Preshock Gas of SN 1006 from Hubble Space Telescope Advanced Camera for Surveys Observations
Raymond, J. C.; Korreck, K. E.; Blair, W. P. +3 more
We derive the preshock density and scale length along the line of sight for the collisionless shock from a deep HST image that resolves the Hα filament in SN 1006 and updated model calculations. The very deep ACS high-resolution image of the Balmer line filament in the northwest quadrant shows that 0.25 cm-3<=n0<=0.4 cm…