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Spectroscopy of Candidate Young Globular Clusters in NGC 1275
Zepf, Stephen E.; Sharples, Ray M.; Carter, Dave +1 more
We present spectra of the brightest member of the population of compact blue objects discovered in the peculiar galaxy NGC 1275 by Holtzman et al. (1992) using Hubble Space Telescope images. These spectra show strong Balmer absorption lines like those observed in A-type stars, as expected if the object is a young globular cluster. The age estimate…
A Search for Microflaring Activity on dMe Flare Stars. I. Observations of the dM8e Star CN Leonis
Carpenter, K. G.; Robinson, R. D.; Percival, J. W. +1 more
Microflares are frequent, short-duration, energetically weak disturbances occurring in the nonradiatively heated regions of the Sun and other magnetically active stars. They are thought to be the low-energy extension of flares commonly seen on active dMe stars and may be a major source of heating the chromosphere and corona of cool stars in genera…
Hubble Space Telescope Observations of Gravitationally Lensed Features in the Rich Cluster AC 114
Smail, Ian; Ellis, Richard S.; Sharples, Ray M. +1 more
Deep Hubble Space Telescope (HST) images of superlative resolution obtained for the distant rich cluster AC 114 (z = 0.31) reveal a variety of gravitational lensing phenomena for which ground-based spectroscopy is available. We present a luminous arc which is clearly resolved by HST and appears to be a lensed z = 0.64 sub-L* spiral gala…
Testing Models for the Quasar Big Blue Bump via Color-Color Diagrams
Elvis, Martin; Wilkes, Belinda J.; Fiore, Fabrizio +3 more
We discuss several models of quasar big blue bump emission in color-color and color-luminosity diagrams. We define several broad passbands: IR (0.8-1.6 µm), VIS (4000-8000 Å), UV (1000-2000 Å), UV1 (1400-2000 Å) and UV2 (1000-1400 Å), and SX (0.2-0.4 keV). The colors have been chosen to investigate characteristics of the big blue bump: (1) I…
Observations of evolving turbulence in the polar solar wind
Balogh, A.; Horbury, T. S.; Forsyth, R. J. +1 more
The Ulysses magnetic field experiment has measured the heliospheric magnetic field in solar wind flows from the Sun's Southern polar coronal hole over a wide range of heliolatitudes and distances. We present an analysis of more than one year of data, covering a latitude range of 40° to 80°S and a distance range of 4.0 to 1.7 AU. We extend an earli…
Multiwavelength Monitoring of the BL Lacertae Object PKS 2155-304. III. Ground-based Observations in 1991 November
Glass, I. S.; Bouchet, P.; Filippenko, A. V. +16 more
We present ground-based observations of the BL Lac object PKS 2155-304 during 1991 November. These data were obtained as part of a large international campaign of observations spanning the electro-magnetic spectrum from the radio waves to the X-rays. The data presented here include radio, and UBVRI fluxes, as well as optical polarimetry. The U to …
Hubble Space Telescope Observations of the Dwarf Nova Z Chamaeleontis through Two Eruption Cycles
Clemens, J. C.; Wood, Janet H.; Dolan, J. F. +8 more
We have obtained the first high-speed photometry of the eclipsing dwarf nova Z Cha at ultraviolet wavelengths with the Hubble Space Telescope (HST). We observed the eclipse roughly every 4 days over two cycles of the normal eruptions of Z Cha, giving a uniquely complete coverage of its outburst cycle. The accretion disk dominated the ultraviolet l…
Tomographic Separation of Composite Spectra. III. Ultraviolet Detection of the Hot Companion of phi Persei
Gies, Douglas R.; Penny, Laura R.; Bagnuolo, William G., Jr. +1 more
We have used archival lUE high-dispersion UV spectra of the Be binary φ Per and published spectroscopic radial velocity curves to reconstruct the individual primary and secondary spectra using Doppler tomography. The primary's spectrum has rotationally broadened photospheric lines (consistent with a spectral type B0.5 III-Ve) and narrow "shell" li…
A snapshot of the continuous emission of the active galactic nucleus in NGC 3783 from gamma-ray to radio wavelengths.
Altieri, B.; Glass, I. S.; Malkan, M. A. +21 more
With the aim of better understanding the physical processes that produce the continuous emission in active galactic nuclei (AGNs), a snapshot of the overall continuous energy distribution of NGC 3783, from γ-ray to radio wavelengths, has been obtained within the framework of the World Astronomy Days. The data collected in this campaign are from GR…
The Stellar Content of 30 Doradus Derived from Spatially Integrated Ultraviolet Spectra: A Test of Spectral Synthesis Models
Robert, Carmelle; Leitherer, Claus; Vacca, William D. +1 more
Using the IUE satellite, we have obtained spatially integrated ultraviolet spectra of three areas within the giant H II region 30 Dor in the Large Magellanic Cloud. The spectra correspond to spatial regions with sizes of 20" x 20", 1' x 1', and 3' x 3', all of which are approximately centered on R136. We have performed a spectral synthesis analysi…