Search Publications
X-Ray Observations of the Coma Cluster in a Broad Energy Band with the INTEGRAL, RXTE, and ROSAT Observatories
Sunyaev, R. A.; Vikhlinin, A.; Lutovinov, A. A. +2 more
We present results of X-ray observations of the Coma Cluster with multiple instruments over a broad energy band. Using the data from the INTEGRAL, RXTE, and ROSAT observatories, we find that the Coma spectrum in the 0.5-107 keV energy band can be well approximated by a thermal plasma emission model with a temperature of T = 8.2 keV. INTEGRAL was u…
The Evolution of Late-Time Optical Emission from SN 1986J
Kirshner, Robert P.; Leibundgut, Bruno; Milisavljevic, Dan +1 more
We present late-time optical images and spectra of the Type IIn supernova SN 1986J. HST ACS/WFC images obtained in 2003 February show it to be still relatively bright, with mF606W = 21.4 and mF814W = 20.0 mag. Compared to 1994 December HST WFPC2 images, SN 1986J shows a decline of only lesssim1 mag in brightness over 8 years.…
Gemini Spectroscopy and HST Imaging of the Stellar Cluster Population in Region B of M82
Bastian, N.; Smith, L. J.; Gallagher, J. S., III +3 more
We present new spectroscopic observations of the stellar cluster population of region B in the prototype starburst galaxy M82 obtained with the Gemini North 8.1 m telescope. By coupling the spectroscopy with UBVI photometry acquired with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST), we derive ages, extinctions, and rad…
The Planetary Nebula NGC 1360: A Test Case of Magnetic Collimation and Evolution after the Fast Wind
López, J. A.; Steffen, W.; García-Segura, G. +2 more
The central star of this nebula has an observed intense magnetic field and the fast wind is no longer present, indicating that a back flow process has probably developed. Long-slit, spatially resolved echelle spectra have been obtained across the main body of NGC 1360 and over its system of bipolar jets. Deep images of the knotty structures of the…
The Blue Straggler Population in the Globular Cluster M53 (NGC 5024): A Combined HST, LBT, and CFHT Study
Pasian, F.; Fontana, A.; Grazian, A. +24 more
We used a proper combination of high-resolution and wide-field multiwavelength observations collected at three different telescopes (HST, LBT, and CFHT) to probe the blue straggler star (BSS) population in the globular cluster M53. Almost 200 BSSs have been identified over the entire cluster extension. The radial distribution of these stars has be…
Influence of Nonuniform Distribution of Acoustic Wavefield Strength on Time-Distance Helioseismology Measurements
Zhao, Junwei; Kosovichev, Alexander G.; Parchevsky, Konstantin V.
By analyzing numerically simulated solar oscillation data we study the influence of nonuniform distribution of acoustic wave amplitude, acoustic source strength, and perturbations of the sound speed on the shifts of acoustic travel times measured by the time-distance helioseismology method. It is found that for short distances, the contribution to…
A Deep 0.3-10 keV Spectrum of the H2O Maser Galaxy IC 2560
Done, Chris; Tilak, Avanti; Greenhill, Lincoln J. +1 more
We present a new XMM-Newton spectrum of the Seyfert 2 nucleus of IC 2560, which hosts H2O maser emission from an inclined Keplerian accretion disk. The X-ray spectrum shows soft excess due to multitemperature ionized plasma, a hard continuum, and strong emission features, from Mg, Si, S, Ca, Fe, and Ni, mainly due to fluorescence. It is…
Contribution to Unresolved Infrared Fluctuations from Dwarf Galaxies at Redshifts of 2-3
Chary, Ranga-Ram; Cooray, Asantha; Sullivan, Ian
In order to understand the origin of clustered anisotropies detected in Spitzer images between 3.6 and 8 µm, we stack the Spitzer IRAC/Great Observatories Origins Deep Survey (GOODS) images at pixel locations corresponding to faint, zAB ~ 27 mag, optical sources with no obvious IR counterparts. We obtain a strong detection of the …
EG And: Far Ultraviolet Spectroscopic Explorer and Hubble Space Telescope STIS Monitoring of an Eclipsing Symbiotic Binary
Espey, Brian R.; McCandliss, Stephan R.; Crowley, Cian
We present highlights and an overview of 20 FUSE and HST STIS observations of the bright symbiotic binary EG And. The main motivation behind this work is to obtain spatially resolved information on an evolved giant star in order to understand the mass-loss processes at work in these objects. The system consists of a low-luminosity white dwarf and …
A Model for the Total Solar Irradiance Based on Active Region Decay
Charbonneau, P.; Crouch, A. D.; Beaubien, G. +1 more
We present a model for the total solar irradiance. The model takes the observed location, timing, and area of emerging active regions as input and produces a time-evolving size distribution of magnetic structures over the solar surface. We assume that the bright magnetic structures (faculae), which counteract the irradiance deficit caused by sunsp…