Search Publications
Revealing the Nature of Algol Disks through Optical and UV Spectroscopy, Synthetic Spectra, and Tomography of TT Hydrae
Peters, Geraldine J.; Miller, Brendan; Budaj, Ján +2 more
We have developed a systematic procedure to study the disks in Algol-type binaries using spectroscopic analysis, synthetic spectra, and tomography. We analyzed 119 Hα spectra of TT Hya, an Algol-type eclipsing interacting binary, collected from 1985 to 2001. The new radial velocities enabled us to derive reliable orbital elements, including a smal…
Speed of Meridional Flows and Magnetic Flux Transport on the Sun
Zhao, Junwei; Kosovichev, Alexander G.; Švanda, Michal
We use the magnetic butterfly diagram to determine the speed of the magnetic flux transport on the solar surface toward the poles. The manifestation of the flux transport is clearly visible as elongated structures extended from the sunspot belt to the polar regions. The slopes of these structures are measured and interpreted as meridional magnetic…
Hydrogen Peroxide on Enceladus
Buratti, B. J.; Jaumann, R.; Momary, T. W. +2 more
Scientists have recently discovered a dynamic, geologically active world in Saturn's icy moon, Enceladus. This small satellite has a south polar hot spot at least 70 K hotter than surrounding regions and a plume of water vapor and ice particles surging from the ``tiger stripe'' cracks that flank the pole. Spectral data of the surface of Enceladus …
New Insights on Interstellar Gas-Phase Iron
Snow, Theodore P.; Jensen, Adam G.
In this paper we report on the gas-phase abundance of singly ionized iron (Fe II) for 51 lines of sight, using data from FUSE. Fe II column densities are derived by measuring the equivalent widths of several UV absorption lines and subsequently fitting those to a curve of growth. Our derivation of Fe II column densities and abundances creates the …
A Statistical Study of Multiply Imaged Systems in the Lensing Cluster Abell 68
Richard, Johan; Ellis, Richard; Kneib, Jean-Paul +8 more
We have carried out an extensive spectroscopic survey with the Keck and VLT telescopes, targeting lensed galaxies in the background of the massive cluster Abell 68. Spectroscopic measurements are obtained for 26 lensed images, including a distant galaxy at z=5.4. Redshifts have been determined for 5 out of 7 multiple-image systems. Through a caref…
The Interaction between Radio Lobes and Hot Gas in the Nearby Radio Galaxies 3C 285 and 3C 442A
Hardcastle, M. J.; Croston, J. H.; Birkinshaw, M. +4 more
We present Chandra observations of two nearby radio galaxies in group environments, 3C 285 and 3C 442A. The host galaxies of both sources are involved in mergers with nearby massive galaxies, and the hot gas in the systems is extended along lines joining the interacting galaxies. Both sources show strong evidence for interactions between the radio…
Precision Masses of the Low-Mass Binary System GJ 623
Ireland, Michael J.; Martinache, Frantz; Lloyd, James P. +2 more
We have used aperture masking interferometry and adaptive optics (AO) at the Palomar 200 inch telescope to obtain precise mass measurements of the binary M dwarf GJ 623. AO observations spread over 3 yr combined with a decade of radial velocity measurements constrain all orbital parameters of the GJ 623 binary system accurately enough to criticall…
Neon and Oxygen Absolute Abundances in the Solar Corona
Landi, E.; Doschek, G. A.; Feldman, U.
In the present work we use the UV spectrum of a solar flare observed with SOHO SUMER to measure the absolute abundance of Ne in the solar atmosphere. The measurement is carried out using the intensity ratio between the allowed 1s2s3S1-1s2p3P2 Ne IX line at 1248.28 Å and the free-free continuum radiation …
A Spectroscopic Study of Field and Runaway OB Stars
Gies, Douglas R.; Boyajian, Tabetha S.; Grundstrom, Erika D. +1 more
Identifying binaries among runaway O- and B-type stars offers valuable insight into the evolution of open clusters and close binary stars. Here we present a spectroscopic investigation of 12 known or suspected binaries among field and runaway OB stars. We find new orbital solutions for five single-lined spectroscopic binaries (HD 1976, HD 14633, H…
Unveiling the Core of the Globular Cluster M15 in the Ultraviolet
Knigge, C.; Charles, P. A.; Long, K. S. +4 more
We have obtained deep FUV and NUV images of the inner region of the dense globular cluster M15 with the HST ACS. The FUV-NUV color-magnitude diagram shows a well-defined track of horizontal branch stars, as well as a trail of blue stragglers and white dwarfs. The main-sequence turnoff is clearly visible at FUV~=23.5 mag and FUV-NUV~=3 mag, and the…