Search Publications
Space Telescope Imaging Spectrograph Observations of Interstellar Oxygen and Krypton in Translucent Clouds
Meyer, David M.; Cartledge, Stefan I. B.; Lauroesch, J. T. +1 more
We have obtained high-resolution Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) observations of O I λ1356 and Kr I λ1236 absorption in 11 sight lines characterized by high extinction, large H I column densities, and/or long path lengths. Previous Goddard High Resolution Spectrograph (GHRS) measurements of these weak featu…
Theoretical Modeling of Infrared Emission from Neutral and Charged Polycyclic Aromatic Hydrocarbons. II.
Tielens, A. G. G. M.; Bakes, E. L. O.; Bauschlicher, Charles W., Jr. +2 more
The nature of the carriers of the interstellar infrared (IR) emission features between 3.3 and 12.7 µm is complex. We must consider emission from a family of polycyclic aromatic hydrocarbons (PAHs) in a multiplicity of cationic charge states (+1, +2, +3, and so on), along with neutral and anionic PAHs. The adopted intrinsic IR cross sections…
Optical Detection of a Variable Millisecond Pulsar Companion in 47 Tucanae
Heinke, Craig O.; Gilliland, Ronald L.; Edmonds, Peter D. +2 more
Using results from radio and X-ray observations of millisecond pulsars in 47 Tucanae, and extensive Hubble Space Telescope U, V, and I imaging of the globular cluster core, we have derived a common astrometric solution good to less than 0.1". A close positional coincidence is found for 47 Tuc U, a 4.3 ms pulsar in a 0.429 day orbit, detected in ra…
Helium White Dwarfs and BY Draconis Binaries in the Globular Cluster NGC 6397
Cool, A. M.; Grindlay, J. E.; Edmonds, P. D. +1 more
We examine 15 orbits of Hubble Space Telescope observations of the nearby post-core-collapsed globular cluster NGC 6397 using narrowband photometry in Hα with broadband photometry in V, R, and I. We recover the candidate helium white dwarfs (He WDs) recently discovered by Cool et al., of which one was examined spectroscopically by Edmonds et al., …
Hard X-Radiation from a Fast Coronal Ejection
Hudson, H. S.; Nitta, N. V.; Shimojo, M. +1 more
We have observed a high-speed coronal ejection in hard X-rays, detectable to an altitude of some 2×105 km in the Yohkoh 23-53 keV energy bands. Simultaneous imaging at 17 and 34 GHz from the Nobeyama radioheliograph shows complex moving features simultaneous with the ejection, including a compact source that we identify with the rapid X…
The Stellar Population and Star Clusters in the Unusual Local Group Galaxy IC 10
Hunter, Deidre A.
We present an analysis of Hubble Space Telescope U, V, I, and Hα images of the peculiar Local Group irregular galaxy IC 10. The images are used to determine the nature of the stellar products in a portion of the recent starburst in this galaxy. We identified 13 stellar associations and clusters, two of which are probably old (>=350 Myr) and the…
Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Arakelian 564. III. Optical Observations and the Optical-UV-X-Ray Connection
Filippenko, A. V.; Martini, P.; Turner, T. J. +36 more
We present the results of a 2 yr long optical monitoring program of the narrow-line Seyfert 1 galaxy Ark 564. The majority of this monitoring project was also covered by X-ray observations (RXTE), and for a period of ~50 days, we observed the galaxy in UV (HST) and X-rays (RXTE and ASCA) simultaneously with the ground-based observations. Rapid and…
NICMOS Observations of Low-Redshift Quasar Host Galaxies
McLeod, K. K.; McLeod, B. A.
We have obtained Near-Infrared Camera and Multi-Object Spectrometer images of 16 radio-quiet quasars observed as part of a project to investigate the ``luminosity/host-mass limit.'' The limit results were presented in a paper by McLeod, Rieke, & Storrie-Lombardi. In this paper, we present the images themselves, along with one- and two-dimensio…
Sustaining the Sun's Magnetic Network with Emerging Bipoles
Title, A. M.; Simon, G. W.; Weiss, N. O.
The Michelson Doppler Imager experiment on SOHO has revealed a ``magnetic carpet'' dominated by the emergence of bipolar magnetic flux in ephemeral active regions, which subsequently split into small flux elements that drift into the magnetic network. The effects of granular and supergranular convection on these flux elements are represented here …
A Short-Timescale Candidate Microlensing Event in the POINT-AGAPE Pixel Lensing Survey of M31
Giraud-Héraud, Y.; Evans, N. W.; Smartt, S. J. +14 more
We report the discovery of a short-duration microlensing candidate in the northern field of the POINT-AGAPE pixel lensing survey toward M31. Almost certainly, the source star has been identified on Hubble Space Telescope archival images, allowing us to infer an Einstein crossing time of tE=10.4 days, a maximum magnification of Amax…