Search Publications
The High-Velocity Gas toward Messier 5: Tracing Feedback Flows in the Inner Galaxy
Brown, Thomas M.; Lehner, Nicolas; Howk, J. Christopher +2 more
We present FUSE and STIS E140M observations of the post-AGB star ZNG 1 in the globular cluster Messier 5 (l = 3.9°, b = + 47.7° d = 7.5 kpc , z = + 5.3 kpc ). High-velocity absorption is seen in C IV, Si IV, O VI, and lower ionization species at LSR velocities of roughly -140 and -110 km s-1. We conclude that this gas is not circumstell…
NGC 346 in the Small Magellanic Cloud. III. Recent Star Formation and Stellar Clustering Properties in the Bright H II Region N66
Henning, Thomas; Gouliermis, Dimitrios A.; Dolphin, Andrew E. +2 more
In the third part of our photometric study of the star-forming region NGC 346/N66 and its surrounding field in the Small Magellanic Cloud (SMC), we focus on the large number of low-mass pre-main-sequence (PMS) stars revealed by the Hubble Space Telescope observations with the Advanced Camera for Surveys. We investigate the origin of the observed b…
The Once and Future Andromeda Stream
Rich, R. Michael; Mori, Masao
We study the interaction between an accreting satellite and the Andromeda galaxy (M31) analytically and numerically, using a high-resolution N-body simulation with 4 × 107 particles. For the first time, we show the self-gravitating response of the disk, the bulge, and the dark matter halo of M31 to an accreting satellite. We reproduce t…
The Dependence of Ephemeral Region Emergence on Local Flux Imbalance
DeRosa, Marc L.; Schrijver, Carolus J.; Hagenaar, Hermance J.
We investigate the distribution and evolution of existing and emerging magnetic network elements in the quiet-Sun photosphere. The ephemeral region emergence rate is found to depend primarily on the imbalance of magnetic flux in the area surrounding its emergence location, such that the rate of flux emergence is lower within strongly unipolar regi…
Characterizing the Low-Redshift Intergalactic Medium toward PKS 1302-102
Weiner, Benjamin J.; Chen, Hsiao-Wen; Mulchaey, John S. +2 more
We present a detailed analysis of the intergalactic metal-line absorption systems in the archival HST STIS and FUSE ultraviolet spectra of the low-redshift quasar PKS 1302-102 (zQSO = 0.2784). We supplement the archive data with CLOUDY ionization models and a survey of galaxies in the quasar field. There are 15 strong Lyα absorbers with…
Solar Rotation Rate and Its Gradients During Cycle 23
Basu, Sarbani; Antia, H. M.; Chitre, S. M.
Available helioseismic data now span almost the entire solar activity cycle 23, making it possible to study solar-cycle-related changes of the solar rotation rate in detail. In this paper we study how the solar rotation rate, in particular, the zonal flows, change with time. In addition to the zonal flows that show a well-known pattern in the sola…
Searching for Dark Matter with X-Ray Observations of Local Dwarf Galaxies
Profumo, S.; Jeltema, T. E.
A generic feature of weakly interacting massive particle (WIMP) dark matter models is the emission of photons over a broad energy band resulting from the stable yields of dark matter pair annihilation. Inverse Compton scattering off cosmic microwave background photons of energetic electrons and positrons produced in dark matter annihilation is exp…
Chandra Localizations and Spectra of INTEGRAL Sources in the Galactic Plane
Kaaret, Philip; Walter, Roland; Tomsick, John A. +2 more
We report on the results of observations of hard X-ray sources in the Galactic plane with the Chandra X-Ray Observatory. The hard X-ray "IGR" sources were discovered by the INTEGRAL satellite, and the goals of the Chandra observations are to provide subarcsecond localizations to obtain optical and infrared counterparts and to provide constraints o…
Luminosity Indicators in the Ultraviolet Spectra of Type Ia Supernovae
Filippenko, Alexei V.; Foley, Ryan J.; Jha, Saurabh W.
We present a complete sample of International Ultraviolet Explorer and Hubble Space Telescope ultraviolet (UV) spectra of Type Ia supernovae (SNe Ia) through 2004. We measure the equivalent width (EW) and blueshifted velocity of the minimum of the one strong UV feature, Fe II λ3250. We also quantify the slope of the near-UV spectra using a new par…
Stellar Exotica in 47 Tucanae
Zurek, David R.; Shara, Michael M.; Long, Knox S. +3 more
We present far-ultraviolet (FUV) spectroscopy obtained with HST for 48 blue objects in the core of 47 Tuc. Based on their position in a FUV-optical color-magnitude diagram, these were expected to include cataclysmic variables (CVs), blue stragglers (BSs), white dwarfs (WDs), and other exotic objects. For a subset of these sources, we also construc…