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Evolution of Cluster Ellipticals at 0.2 < z < 1.2 from Hubble Space Telescope Imaging,
Barrientos, L. Felipe; López-Cruz, Omar; Schade, David
Two-dimensional surface photometry derived from Hubble Space Telescope imaging is presented for a sample of 225 early-type galaxies (assumed to be cluster members) in the fields of nine clusters at redshifts 0.17 < z < 1.21. The 94 luminous ellipticals (MAB(B) < -20 selected by morphology alone with no reference to color) form …
The Apparent Morphology of Peculiar Galaxies at Intermediate to High Redshifts
Vacca, W. D.; Hibbard, J. E.
To understand the range of morphologies observed in the galaxy population at high redshift, it is instructive to evaluate the appearance of local peculiar galaxies when placed at cosmological distances. To this end, we use rest-frame ultraviolet (UV), B- and V-band images of five nearby (ζ<0.02) interacting and/or starbursting galaxies to simul…
Kinematics of the Interstellar Medium in NGC 1705: Implications for Distant Star-Forming Galaxies
Heckman, Timothy M.; Leitherer, Claus
We report the results of space-ultraviolet (UV) spectroscopy of the super star cluster `1' in the nearby dwarf starburst galaxy NGC 1705, using the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The exceptionally high UV flux and surface brightness of NGC 1705-1 makes it ideal for studying how UV spectral diagnostics can be us…
The Variability and Spectrum of NGC 5548 in the Extreme Ultraviolet
Malkan, M. A.; Clavel, J.; Kriss, G. A. +8 more
We have measured the light curve and spectrum of NGC 5548 obtained with the Extreme Ultraviolet Explorer (EUVE) during a period when the galaxy was also intensively monitored with the Hubble Space Telescope, the International Ultraviolet Explorer, and ground-based telescopes. NGC 5548 was observed with EUVE for a total of about 20 days spread over…
Low-Mass Binaries in the Hyades: A Scarcity of Brown Dwarfs
Gizis, John E.; Reid, I. Neill
We have obtained HST Planetary Carnera observations of a total of 53 low-mass (M<0.3Msun) members of the Hyades cluster. Nine of these stars are resolved as binaries, with separations between 0.1 and 3.1 arcseconds, while a further three are probably equal-mass systems at smaller separations. Allowing for observational selection effe…
Nuclear Spiral and Ring Star-forming Structures and the Starburst--Active Galactic Nucleus Connection in Barred Spirals NGC 3351 and NGC 4303
Colina, Luis; Alberdi, A.; Krabbe, A. +2 more
A high-resolution Hubble Space Telescope WFPC2 F218W UV image of the barred spiral NGC 4303 (classified as a LINER-type active galactic nucleus [AGN]) reveals for the first time the existence of a nuclear spiral structure of massive star-forming regions all the way down to the UV-bright unresolved core (size <= 8 pc) of an active galaxy.
T…Solar Wind Acceleration by Solitary Waves in Coronal Holes
Davila, J. M.; Ofman, L.
Coronal holes are well-known sources of the high-speed solar wind; however, the exact acceleration mechanism of the fast wind is still unknown. We solve numerically the time-dependent, nonlinear, resistive 2.5-dimensional MHD equations and find that solitary waves are generated in coronal holes nonlinearly by torsional Alfvén waves. The solitary w…
The Ionization Structure of the Narrow-Line Region of NGC 1068 and Its Relationship to the Extended Radio Emission
Macchetto, F. D.; Capetti, A.; Axon, D. J.
Hubble Space Telescope (HST)/WFPC2 imaging has been used to investigate the emission-line structure of the narrow-line region (NLR) of the Seyfert 2 galaxy NGC 1068 and its relationship to the extended radio emission. We find that the morphology and the ionization properties of the NLR of NGC 1068 are dominated by the interaction with the radio je…
S1040 in M67: A Post--Mass Transfer Binary with a Helium Core White Dwarf
Bergeron, P.; Stecher, T. P.; Di Stefano, R. +2 more
We have obtained spectra of the yellow giant S1040 in the open cluster M67 using the Goddard High-Resolution Spectrograph (GHRS) and the Faint Object Spectrograph on the Hubble Space Telescope. S1040 is a single-lined spectroscopic binary with a 42.8 day period that occupies a ``red straggler'' position in the M67 color-magnitude diagram (CMD), 0.…
The Intermediate-mass Stellar Population of the Large Magellanic Cloud Cluster NGC 1818 and the Universality of the Stellar Initial Mass Function
Grillmair, Carl J.; Holtzman, Jon A.; Light, Robert M. +1 more
We present stellar photometry from Hubble Space Telescope images of NGC 1818, a young populous star cluster in the Large Magellanic Cloud. The cluster stars in both the core and the outlying regions are well resolved, and the photometry extends to a V magnitude of 26, corresponding approximately to a K4 V star. With the use of isochrones, we compu…