Search Publications
Model Calculations for Io's Atmosphere at Eastern and Western Elongations
Smyth, William H.; Wong, Mau C.
Numerical calculations are performed for Io's sublimation atmosphere at eastern and western elongations using an improved version of the multispecies hydrodynamic model first developed by Wong and Johnson (1996). Subsolar SO 2 frost temperatures of 113 and 120 K are adopted to cover a range of plausible atmospheric abundances that are c…
Structure and chemical composition of the silicate dust around OH/IR stars
Dartois, E.; Wiesemeyer, H.; Demyk, K. +2 more
Using a radiative transfer code we have studied the dust shells of the two OH/IR stars IRAS 17004-4119 (OH344.93) and IRAS 17411-3154 (OH357). The ISO-SWS spectra of both sources exhibit deep amorphous silicate absorption bands at 9.8 and 17.5 mu m together with crystalline silicate emission bands at 33.6, 40.5 and 43 mu m. In both sources the 9.8…
Discovery of a Nuclear Gas Bar Feeding the Active Nucleus in Circinus
Maiolino, R.; Rieke, G. H.; Alonso-Herrero, A. +4 more
We report the discovery of gas inflow motions toward the active nucleus of the Circinus galaxy caused by the nonaxisymmetric potential of a nuclear gas bar. Evidence for dust associated with the bar comes from the HST/NICMOS H-K color map, whereas the streaming motions along the gas bar are seen in the velocity field of the H2 S(1) (1-0…
Stellar Populations in the Host Galaxies of Markarian 1014, IRAS 07598+6508, and Markarian 231
Stockton, Alan; Canalizo, Gabriela
We present deep spectroscopic and imaging data of the host galaxies of Mrk 1014, IRAS 07598+6508, and Mrk 231. These objects form part of both the QSO and the ultraluminous infrared galaxy (ULIG) families and may represent a transition stage in an evolutionary scenario. Our imaging shows that all three objects have highly perturbed hosts with tida…
Detection of Extended Thermal Infrared Emission around the Vega-like Source HD 141569
Telesco, C. M.; Fisher, R. S.; Piña, R. K. +2 more
We report the detection of extended IR emission at 10.8 and 18.2 µm around the Vega-like source HD 141569. Mid-IR imaging with OSCIR on Keck II shows emission from dust extending out to 100 AU from the B9.5 Ve star. Our modeling of the dust places an upper limit of ~2 µm on the diameter of the mid-IR-emitting particles if they are Mie …
Empirical Verification of the Fe II Oscillator Strengths in the FUSE Bandpass
Sembach, Kenneth R.; Roth, Katherine C.; Howk, J. Christopher +1 more
We report empirical determinations of atomic oscillator strengths, or f-values, for 11 ground-state transitions of Fe II in the wavelength range 1050<~λ<~1150 Å. We use ultraviolet absorption-line observations of interstellar material toward stars in the Galaxy and the Magellanic Clouds taken with Copernicus, the Goddard High Resolution Spec…
Evidence of a North-South Asymmetry in the Heliosphere Associated with a Southward Displacement of the Heliospheric Current Sheet
Smith, E. J.; Szabo, A.; Lepping, R. P. +2 more
Evidence of a north-south asymmetry in the global heliosphere, first inferred from Ulysses cosmic-ray observations, is investigated using simultaneous Ulysses and Wind magnetic field observations. Such an asymmetry, presumably associated with a southward displacement of the heliospheric current sheet (HCS), is expected to produce significantly dif…
A four-fluid turbulence-driven solar wind model for preferential acceleration and heating of heavy ions
Habbal, Shadia R.; Esser, Ruth; Hu, You Qiu
We present for the first time a one-dimensional, four-fluid turbulence-driven solar wind model in order to investigate the preferential acceleration and heating of heavy ions by the resonant cyclotron interaction with parallel-propagating left-hand-polarized ion cyclotron waves. The model contains four species: electrons, protons, alpha particles,…
Panchromatic Study of Nearby Ultraviolet-bright Starburst Galaxies: Implications for Massive Star Formation and High-Redshift Galaxies
Conselice, Christopher J.; Calzetti, Daniela; Gallagher, John S. +2 more
We present a panchromatic study of nearby starburst galaxies from the ultraviolet to the visible, including narrowband Hα using Wisconsin-Indiana-Yale-NOAO (WIYN) and Hubble Space Telescope data, to determine how star formation processes affect the morphologies and integrated fluxes of nearby starbursts. We find that the UV and Hα morphologies of …
A High Signal-to-Noise Ultraviolet Spectrum of NGC 7469: New Support for Reprocessing of Continuum Radiation
Peterson, Bradley M.; Kriss, Gerard A.; Zheng, Wei +1 more
From 1996 June 10 to 1996 July 29, the International AGN Watch monitored the Seyfert 1 galaxy NGC 7469 using the International Ultraviolet Explorer, the Rossi X-Ray Timing Explorer, and a network of ground-based observatories. On 1996 June 18, in the midst of this intensive monitoring period, we obtained a high signal-to-noise snapshot of the UV s…