Search Publications
A G1-like Globular Cluster in NGC 1023
Larsen, Søren S.
The structure of a very bright (MV=-10.9) globular cluster in NGC 1023 is analyzed on two sets of images taken with the Hubble Space Telescope. From careful modeling of King profile fits to the cluster image, a core radius of rc=0.55+/-0.1 pc, effective radius Re=3.7+/-0.3 pc, and a central surface brightness of &m…
Hubble Space Telescope STIS Observations of the Wolf-Rayet Star HD 5980 in the Small Magellanic Cloud. II. The Interstellar Medium Components
Walborn, Nolan R.; Morrell, Nidia; Tsvetanov, Zlatan +6 more
Observations of the interstellar and circumstellar absorption components obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) along the line of sight toward the Wolf-Rayet-luminous blue variable (LBV) system HD 5980 in the Small Magellanic Cloud are analyzed. Velocity components from C I, C I*, C II, C II*, C IV, N …
New Proplyds, Outflows, Shocks, and a Reflection Nebula in M43 and the Outer Parts of the Orion Nebula
O'Dell, C. R.
Hubble Space Telescope WFPC2 images made as planned parallel observations have produced emission-line images of fields in the outer portions of the Orion Nebula and near the center of the companion H II region, M43. Examination of these images have uncovered three new bright proplyds and one silhouette proplyd. Two of the bright proplyds lie withi…
Orientation and Speed of the Parsec-Scale Jet in NGC 4261 (3C 270)
Jones, Dayton L.; Wehrle, Ann E.; Piner, B. Glenn
NGC 4261 (3C 270) is an elliptical galaxy containing a 300 pc-scale nuclear disk of gas and dust imaged by the Hubble Space Telescope (HST), around a central supermassive black hole. Previous VLBI observations of NGC 4261 revealed a gap in emission in the radio counterjet, presumably due to free-free absorption in the inner parsec of the accretion…
Proper Motion and Excitation Structure of the Expanding Ionized Rings around RY Scuti
Smith, Nathan; Gehrz, Robert D.; Goss, W. M.
Multiepoch HST/WFPC2 images of the massive eclipsing binary RY Scuti reveal that the compact ionized rings in its circumstellar nebula are expanding. Radio images of the free-free continuum at 15 GHz obtained with the Very Large Array confirm the expansion rate and extend the temporal baseline. Combined Hα and radio proper-motion measurements of t…
The Tolman Surface Brightness Test for the Reality of the Expansion. I. Calibration of the Necessary Local Parameters
Sandage, Allan; Lubin, Lori M.
The extensive CCD photometry by Postman & Lauer in the Cape/Cousins R photometric band for first-ranked cluster elliptical and S0 galaxies in 118 low redshift (<z>=0.037) clusters is analyzed for the correlations between average surface brightness, linear radius, and absolute magnitude. The purpose is to calibrate the correlations betwee…
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…