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Massive Star Formation in Luminous Infrared Galaxies: Giant H II Regions and Their Relation to Super-Star Clusters
Rieke, George H.; Alonso-Herrero, Almudena; Rieke, Marcia J. +1 more
We have used Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer broadband (at 1.6 µm) and narrowband Paα (λrest=1.87 µm) images to identify, respectively, star clusters and H II regions in a sample of eight luminous infrared galaxies (LIRGs). These observations have revealed the presence of a large pop…
Abundance Gradients and the Role of Supernovae in M87
Gastaldello, Fabio; Molendi, Silvano
We make a detailed measurement of the metal abundance profiles and metal abundance ratios of the inner core of M87/Virgo observed by XMM-Newton during the performance verification phase. We use multitemperature models for the inner regions, and we compare the plasma codes APEC and MEKAL. We confirm the strong heavy-element gradient previously foun…
High resolution soft X-ray spectroscopy of M 87 with the reflection grating spectrometers on XMM-Newton
Böhringer, H.; Kaastra, J. S.; Branduardi-Raymont, G. +11 more
We present high-resolution X-ray spectroscopic observations of M 87 with the Reflection Grating Spectrometers on XMM-Newton. We detect strong K-shell line emission from N, O, Ne, Mg, some emission from He-like Si, a fully resolved set of Fe L-shell emission spectra, and some emission from C. The angular intensity distributions of the strong emissi…
Monitoring the Evolution of the X-Ray Remnant of SN 1987A
Garmire, Gordon P.; Park, Sangwook; McCray, Richard +4 more
We report on the results of our monitoring program of the remnant of SN 1987A with the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. Two new observations have been performed in AO2, bringing the total to four monitoring observations over the past 2 years. Over this time period, new techniques for correction of ``…
Solar p-modes and surface magnetic fields: Is there an acoustic emission?. MDI/SOHO observations
Haber, D.; Jain, R.
We study the effect of magnetism on the surface amplitude of p-modes by creating power maps using Doppler velocity, line-depth and continuum intensity data taken by the Michelson Doppler Interferometer (MDI) instrument on board SOHO. This analysis, using proper tracking procedures, of MDI line-depth data and its comparison with the simultaneous Do…
Three-dimensional Model of the Structure and Evolution of Coronal Mass Ejections
Tokman, M.; Bellan, P. M.
We present a new three-dimensional magnetohydrodynamic (MHD) model that describes the evolution of coronal magnetic arcades in response to photospheric flows. The dynamics of the system is discussed, and it is shown that the model reproduces a number of features characteristic of coronal mass ejection (CME) observations. In particular, we propose …
The Structure and X-Ray Recombination Emission of a Centrally Illuminated Accretion Disk Atmosphere and Corona
Raymond, J. C.; Liedahl, D. A.; Jimenez-Garate, M. A.
We model an accretion disk atmosphere and corona photoionized by a central X-ray continuum source. We calculate the opacity and one-dimensional radiation transfer for an array of disk radii to obtain the two-dimensional structure of the disk and its X-ray recombination emission. The atmospheric structure is extremely insensitive to the viscosity α…
Speckle Observations of Binary Stars with the WIYN Telescope. II. Relative Astrometry Measures during 1998-2000
Horch, Elliott P.; van Altena, William F.; Ninkov, Zoran +3 more
Five hundred twelve relative astrometry measures are presented for 253 double stars, including 53 double stars discovered by Hipparcos. In 15 cases, relative astrometry is reported for the first time for newly confirmed pairs. In addition, 20 high-quality nondetections of companions are reported for stars suspected of being nonsingle by Hipparcos.…
Emission Line Properties of Active Galactic Nuclei from a pre-COSTAR Faint Object Spectrograph Hubble Space Telescope Spectral Atlas
Green, Paul J.; Forster, Karl; Koratkar, Anuradha +3 more
UV/optical emission lines offer some of the most detailed information obtainable about the intrinsic properties of quasars. Studies of the density, ionization and metal abundance of gas near the accreting black hole are probed through an intriguing but poorly understood complex of correlations between emission lines and overall quasar spectral ene…
A Uniform Analysis of the Lyα Forest at z=0-5. V. The Extragalactic Ionizing Background at Low Redshift
Bechtold, Jill; Kulkarni, Varsha P.; Dobrzycki, Adam +2 more
In Paper III of our series, ``A Uniform Analysis of the Lyα Forest at z=0-5,'' we presented a set of 270 quasar spectra from the archives of the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST). A total of 151 of these spectra, yielding 906 lines, are suitable for using the proximity effect signature to measure J(ν0),…