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The Globular Cluster Systems in the Coma Ellipticals. III. The Unique Case of IC 4051
Harris, William E.; Woodworth, Sean C.
IC 4051 is a giant E galaxy on the outskirts of the Coma Cluster core. Using archival HST WFPC2 data, we derive the metallicity distribution, luminosity function, and spatial structure of its globular cluster system (GCS). The metallicity distribution derived from the V-I colors has a mean <Fe/H>~=-0.3, a near-complete lack of metal-poor clu…
What Produced the Ultraluminous Supernova Remnant in NGC 6946?
Chu, You-Hua; Gruendl, Robert A.; Dunne, Bryan C.
The ultraluminous supernova remnant (SNR) in NGC 6946 is the brightest known SNR in X-rays, about 1000 times brighter than Cas A. To probe the nature of this remnant and its progenitor, we have obtained high-dispersion optical echelle spectra. The echelle spectra detect Hα, [N II], and [O III] lines and resolve these lines into a narrow (FWHM ~20-…
The Age of the Inner Halo Globular Cluster NGC 6652
Sarajedini, Ata; Chaboyer, Brian; Armandroff, Taft E.
Hubble Space Telescope (V, I) photometry has been obtained for the inner halo globular cluster NGC 6652. The photometry reaches ~4 mag below the turnoff and includes a well-populated horizontal branch. This cluster is located close to the Galactic center, at RGC~=2.0 kpc, with a reddening of E(V-I)=0.15+/-0.02, and has a metallicity of …
Recent Star Formation in Several Galaxies of the Tidally Disturbed System HCG 31
Johnson, Kelsey E.; Conti, Peter S.
High-resolution (0.7" to 0.8") Hα images of the Hickson Compact Group 31 (HCG 31) obtained with the WIYN telescope are used in conjunction with broadband optical images from the Hubble Space Telescope (HST) to examine the star formation history and properties of the component galaxies. The high spatial resolution of the WIYN telescope has allowed …
On the Nature of Linear Structures in the Helix and Orion Nebulae
O'Dell, C. R.
Linear features of up to 0.25 pc length are seen in both the Helix Nebula and the Orion Nebula. These features are most evident in emission-line ratio images. It is demonstrated that in both objects the features are along projections of lines between the dominant star and an optically thick compact feature (the cometary knots in the Helix and the …
Face-on Galaxies NGC 524 and NGC 6340: Chemically Decoupled Nuclei and Inclined Circumnuclear Disks
Sil'chenko, O. K.
The central regions of the early-type disk galaxies NGC 524 and NGC 6340 have been investigated with the Multipupil Field Spectrograph at the 6 m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. We confirm the existence of chemically distinct stellar nuclei in these galaxies, which had been claimed earlier. Th…
Background and Scattered-Light Subtraction in the High-Resolution Echelle Modes of the Space Telescope Imaging Spectrograph
Sembach, Kenneth R.; Howk, J. Christopher
We present a simple, effective approach for estimating the on-order backgrounds of spectra taken with the highest resolution modes of the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. Our scheme for determining the on-order background spectrum for STIS E140H and E230H observations uses moderate-order polynomial f…
Young Stellar Nuclei in the Lenticular Galaxies. II. NGC 7280
Sil'chenko, O. K.; Afanasiev, V. L.
We have undertaken bidimensional spectroscopy of the central part of the nearby lenticular galaxy NGC 7280 with the Multi-Pupil Fiber Spectrograph of the 6 m telescope of the Special Astrophysical Observatory. We find a rather young stellar nucleus, with a mean population age of 1.5+/-0.5 Gyr, which is more metal-rich than the bulge at R~1 kpc by …
Hubble Space Telescope STIS Observations of the Cygnus Loop: Spatial Structure of a Nonradiative Shock
Blair, William P.; Raymond, John C.; Long, Knox S. +1 more
We present a spatially resolved ultraviolet spectrum of a nonradiative shock front in the Cygnus Loop, obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. The spectrum covers the wavelength range 1118-1716 Å with an effective spectral resolution of ~12 Å. The 0.1" spatial resolution of these data provides a …
The Near-Ultraviolet Continuum of Late-Type Stars
Lambert, David L.; Allende Prieto, Carlos
Analyses of the near-ultraviolet continuum of late-type stars have led to controversial results regarding the performance of state-of-the-art model atmospheres. The release of the homogeneous International Ultraviolet Explorer (IUE) final archive and the availability of the high-accuracy Hipparcos parallaxes provide an opportunity to revisit this …