Search Publications
Evolution of Field Early-Type Galaxies: The View from GOODS CDFS
Lisker, Thorsten; Mobasher, Bahram; Ferreras, Ignacio +2 more
We explore the evolution of field early-type galaxies in a sample extracted from the ACS images of the southern GOODS field. The galaxies are selected by means of a nonparametric analysis, followed by visual inspection of the candidates with a concentrated surface brightness distribution. We furthermore exclude from the final sample those galaxies…
On the Limb Darkening, Spectral Energy Distribution, and Temperature Structure of Procyon
Ludwig, H. -G.; Kervella, P.; Aufdenberg, J. P.
We have fit synthetic visibilities from three-dimensional (CO5BOLD+PHOENIX) and one-dimensional (PHOENIX, ATLAS 12) model stellar atmospheres of Procyon (F5 IV) to high-precision interferometric data from the VLT Interferometer (K band) and from the Mark III interferometer (500 and 800 nm). These data sets provide a test of theoretical …
Intrinsic Curvature in the X-Ray Spectra of BL Lacertae Objects
Perlman, Eric S.; Georganopoulos, Markos; Stocke, John T. +10 more
We report results from XMM-Newton observations of 13 X-ray bright BL Lacertae objects, selected from the Einstein Slew Survey sample (SSS). The survey was designed to look for evidence of departures of the X-ray spectra from a simple power-law shape (i.e., curvature and/or line features) and to find objects worthy of deeper study. Our data are gen…
Ultraviolet, X-Ray, and Optical Radiation from the Geminga Pulsar
Romani, R. W.; Pavlov, G. G.; Zavlin, V. E. +1 more
We observed the γ-ray pulsar Geminga with the FUV-MAMA and NUV-MAMA detectors of the Space Telescope Imaging Spectrometer to measure Geminga's spectrum and pulsations in the ultraviolet. The slope of the far-ultraviolet (FUV) spectrum is close to that of a Rayleigh-Jeans spectrum, suggesting that the FUV radiation is dominated by thermal emission …
The Local Helioseismology of Inclined Magnetic Fields and the Showerglass Effect
Braun, D. C.; Cally, P. S.; Lindsey, C. +1 more
We present evidence for the dependence of helioseismic Doppler signatures in active regions on the line-of-sight angle in inclined magnetic fields. Using data from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory, we performed phase-sensitive holography in the penumbrae of sunspots over the course of several days …
On the Nature of Coronal EIT Waves
Erdélyi, R.; Ballai, I.; Pintér, B.
Large-scale eruption events in the solar atmosphere can generate global waves, i.e., waves that propagate over distances comparable to the solar radius. In the low solar corona, global waves observed by SOHO EIT, generated by coronal mass ejections or flares, are usually referred to as ``EIT waves.'' The nature of these global waves is the subject…
M31's Heavy-Element Distribution and Outer Disk
MacArthur, Lauren A.; Courteau, Stéphane; Worthey, Guy +1 more
Hubble Space Telescope imaging of 11 fields in M31 were reduced to color-magnitude diagrams. The fields were chosen to sample all galactocentric radii to 50 kpc (~9 disk scale lengths, or >99.9% of the total light enclosed). The colors of the red giants at each pointing map to an abundance distribution with errors of order 0.1 dex in [M/H]. The…
First Soft X-Ray Observations of Global Coronal Waves with the GOES Solar X-Ray Imager
Mann, G.; Aurass, H.; Warmuth, A.
We present the first observations of global coronal waves obtained with the Solar X-Ray Imager (SXI) aboard the GOES-12 satellite. Focusing on six events, the basic morphological and kinematic characteristics of the waves observed in soft X-rays are derived. Taking advantage of SXI's high temporal cadence and comparing the wave signatures with ext…
The X-Ray Spectral Properties and Variability of Luminous High-Redshift Active Galactic Nuclei
Brandt, W. N.; Strauss, Michael A.; Vignali, C. +4 more
We perform a detailed investigation of moderate- to high-quality X-ray spectra of 10 of the most luminous active galactic nuclei (AGNs) known at z>4 (up to z~6.28). This study includes five new XMM-Newton observations and five archived X-ray observations (four by XMM-Newton and one by Chandra). We find that the X-ray power-law photon indices of…
Infall, the Butcher-Oemler Effect, and the Descendants of Blue Cluster Galaxies at z~0.6
Franx, Marijn; Illingworth, Garth D.; Tran, Kim-Vy H. +3 more
Using wide-field Hubble Space Telescope WFPC2 imaging and extensive Keck LRIS spectroscopy, we present a detailed study of the galaxy populations in MS 2053-04, a massive, X-ray-luminous cluster at z=0.5866+/-0.0011. Analysis of 149 confirmed cluster members shows that MS 2053 is composed of two structures that are gravitationally bound to each ot…