Search Publications
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…
On the Solar Origins of Open Magnetic Fields in the Heliosphere
DeRosa, Marc L.; Schrijver, Carolus J.; Rust, David M. +4 more
A combination of heliospheric and solar data was used to identify open magnetic fields stretching from the lower corona to Earth orbit. 35 near-relativistic electron beams detected at the ACE spacecraft "labeled" the heliospheric segments of the open fields. An X-ray flare occurred <20 minutes before injection of the electrons in 25 events. The…
Effects of Solar Active Regions on Meridional Flows
Zhao, Junwei; Kosovichev, Alexander G.; Švanda, Michal
The aim of this Letter is to extend our previous study of the solar-cycle variations of meridional flows and to investigate their latitudinal and longitudinal structure in the subphotospheric layer, especially their variations in magnetic regions. Helioseismology observations indicate that mass flows around active regions are dominated by inflows …
The Extended Fe Distribution in the Intracluster Medium and the Implications Regarding AGN Heating
David, Laurence P.; Nulsen, Paul E. J.
We present a systematic analysis of XMM-Newton observations of eight cool-core clusters of galaxies and determine the Fe distribution in the intracluster medium relative to the stellar distribution in the central dominant galaxy (CDG). Our analysis shows that the Fe is significantly more extended than the stellar mass in the CDG in all of the clus…
A Giant Metrewave Radio Telescope Multifrequency Radio Study of the Isothermal Core of the Poor Galaxy Cluster AWM 4
Raychaudhury, Somak; Clarke, Tracy E.; Mazzotta, Pasquale +7 more
We present a detailed radio morphological study and spectral analysis of the wide-angle tail radio source 4C +24.36 associated with the dominant galaxy in the relaxed galaxy cluster AWM 4. Our study is based on new high-sensitivity GMRT observations at 235, 327, and 610 MHz and on literature and archival data at other frequencies. We find that the…