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AB Dor in '94. I. Hubble Space Telescope Goddard High Resolution Spectrogaph Observations of the Quiescent Chromosphere of an Active Star
Savage, B. D.; Ebbets, D. C.; Carpenter, K. G. +15 more
We analyze Hubble Space Telescope/Goddard High Resolution Spectrograph spectra of AB Doradus, the prototypical, ultrarapidly rotating K dwarf. We observed chromospheric (Mg II) and transition-region (C II, Si IV, C IV, and N V) lines periodically throughout the stellar rotation period and provide a low-dispersion stellar atlas of 78 emission lines…
Nuclear Turnoff Times for ONEMG Novae Determined Using Ultraviolet Spectral Evolution
Shore, Steven N.; Starrfield, Sumner; Vanlandingham, Karen M. +1 more
Classical novae go through a phase of constant bolometric luminosity as any remaining hydrogen in the accreted layers on the white dwarf is converted to helium. The length of this phase is dependent on many factors, including the amount of mass left on the white dwarf after the explosive phase of the outburst, the white dwarf's mass, and the effic…
Hubble Space Telescope and Ground-based Spectroscopy of K648 in M15
Ford, Holland; Bianchi, Luciana; Bohlin, Ralph +2 more
We derive some element abundances for the central star of the planetary nebula K648 from analysis of Hubble Space Telescope Faint Object Spectrograph spectra (1200-3300 Å). Carbon is found to be approximately 4 times overabundant with respect to solar values, while oxygen is underabundant and silicon about solar, and He/H=0.6. The stellar continuu…
Hubble Space Telescope-NICMOS Observations of M31'S Metal-Rich Globular Clusters and Their Surrounding Fields. II. Results
Rich, R. Michael; Jablonka, Pascale; Frogel, Jay A. +6 more
We have obtained HST-NICMOS observations of five of M31's most metal-rich globular clusters: G1, G170, G174, G177, and G280. For the two clusters farthest from the nucleus, G1 and G280, we statistically subtract the field population and estimate metallicities using K-(J-K) color-magnitude diagrams (CMDs). Based on the slopes of their infrared gian…
Radial Color Gradients in K+A Galaxies in Distant Clusters of Galaxies
Caldwell, Nelson; Rose, James A.; Bartholomew, Lindsay J. +1 more
Galaxies in rich clusters with z>~0.3 are observed to have a higher fraction of photometrically blue galaxies than their nearby counterparts. This raises the important question of what environmental effects can cause the termination of star formation between z~0.3 and the present. The star formation may be truncated because of ram pressure stri…
The Metal-rich Globular Cluster NGC 6553: Observations with WFPC2, STIS, and NICMOS
Tanvir, Nial; Gilmore, Gerard; Santiago, Basilio +4 more
We present a Hubble Space Telescope study of the metal-rich globular cluster NGC 6553 using WFPC2, NICMOS, and STIS. Our primary motivation is to calibrate the STIS broadband LP magnitude against V555 and I814 magnitudes for stars of known metallicity and absolute (visual) magnitude, for application to our study of LMC globul…
A Mid-Infrared Spectral Survey of Galactic Wolf-Rayet Stars
Houck, J. R.; Smith, J. D. T.
We present 8-13 µm spectra at resolution R~600 of 29 northern Galactic Wolf-Rayet stars, including the first ever reported mid-infrared (MIR) spectrum for many. Among the subtypes of the stars studied were 14 WC, 13 WN, 1 WN/WC, and an additional reclassified WN. Lines of He I and He II, along with fine-structure lines of Ne II and S IV, are…
Near-Infrared Photometry of Globular Clusters NGC 6287 and NGC 6341 (M92): The Formation of the Galactic Halo
Stetson, Peter B.; Lee, Jae-Woo; Carney, Bruce W. +1 more
We present Hubble Space Telescope (HST) Near Infrared Camera and Multi-Object Spectrometer (NICMOS) camera 3 photometry of the inner halo globular cluster NGC 6287 and the intermediate halo globular cluster NGC 6341 (M92). Our photometric measurements range from the lower red giant branch to ~3 mag below the main-sequence turnoff, allowing us to d…
The Rapid Burster in Liller 1: The Chandra X-Ray Position and a Search for an Infrared Counterpart
Anderson, Scott F.; Margon, Bruce; Deutsch, Eric W. +1 more
Despite the unique X-ray behavior of the compact bursting X-ray source MXB 1730-335, the ``Rapid Burster'' (RB) in the highly reddened globular cluster Liller 1, to date there has been no known optical/IR counterpart for the object, no precise astrometric solution that correlates X-ray, radio, and optical positions and thus restricts the number of…
A Comparison between PAα and Hα Emission: The Relation between Mean H II Region Reddening, Local Gas Density, and Metallicity
Quillen, Alice C.; Yukita, Mihoko
We measure reddenings to H II regions in NGC 1512, 2903, 4449, and 6946, and M51 from Hubble Space Telescope (HST) Paα and Hα images. Extinctions range from AV~5 to 0 depending upon the galaxy. For the galaxies with HST images in both lines, NGC 1512, NGC 2903, and M51, the Paα and Hα emission are almost identical in morphology, which i…