Search Publications
The Spectrum of the Solar Supergranulation: Multiple Nonwave Components
Toomre, Juri; Lisle, Jason P.; Rast, Mark P.
It has recently been suggested that the solar supergranulation undergoes oscillations, with a spectrum of superposed traveling waves of unknown origin showing excess prograde power to yield superrotation. We show here that the observed supergranular spectrum does not necessarily imply a wave origin but is instead consistent with two components of …
An XMM-Newton Observation of the High Magnetic Field Radio Pulsar PSR B0154+61
Lyne, A. G.; Gonzalez, M. E.; Kaspi, V. M. +1 more
We present the results obtained from a 31 ks XMM-Newton observation of the high magnetic field radio pulsar PSR B0154+61. This relatively nearby pulsar has an inferred dipole surface magnetic field strength of 2.1×1013 G, among the highest in the population. This makes the pulsar a possible transition object between the classical radio …
Shocked Clouds in the Vela Supernova Remnant
Nichols, Joy S.; Slavin, Jonathan D.
Unusually strong high-excitation C I has been detected in 11 lines of sight through the Vela supernova remnant (SNR) by means of UV absorption line studies of IUE data. Most of these lines of sight lie near the western edge of the bright X-ray region of the SNR in a spatially distinct band approximately 1° by 4° oriented approximately north-south.…
Properties of the Lower Transition Region: The Widths of Optically Allowed and Intersystem Spectral Lines
Doschek, G. A.; Feldman, U.
The widths of spectral lines in the ultraviolet (UV) and extreme ultraviolet (EUV) spectral regions that are formed in the solar transition region and corona are usually greater than the optically thin widths due to thermal Doppler broadening calculated under the assumption of ionization equilibrium. Although opacity can explain the widths of some…
[O I] 63 Micron Emission from High- and Low-Luminosity Active Galactic Nucleus Galaxies
Beichman, Charles A.; Dale, Daniel A.; Malhotra, Sangeeta +3 more
The Infrared Space Observatory (ISO) was used to search for a tracer of the warm and dense neutral interstellar medium, the [O I] 63.18 µm line, in four ultraluminous IRAS sources lying at redshifts between 0.6 and 1.4. While these sources are quasars, their infrared continuum emission suggests a substantial interstellar medium. No [O I] flu…
Theoretical Prediction of an Observed Solar g-Mode
Guzik, Joyce A.; Cox, Arthur N.
This Letter considers the weak but persistent radial velocity variations measured by the Global Oscillations at Low Frequencies instrument on the Solar and Heliospheric Observatory satellite at 75.55 minutes (220.6 µHz), which is very close to our new theoretical solar model period prediction of 75.15 minutes (221.8 µHz) for the angula…
Mass and Angular Momentum Transfer in the Massive Algol Binary RY Persei
Gies, D. R.; Peters, G. J.; Huang, W. +12 more
We present an investigation of the Hα emission-line variations observed in the massive Algol binary RY Per. We give new radial velocity data for the secondary based on our optical spectra and for the primary based on high-dispersion UV spectra. We present revised orbital elements and an estimate of the primary's projected rotational velocity (whic…
Close Association of an Extreme-Ultraviolet Sunspot Plume with Depressions in the Sunspot Radio Emission
Brosius, Jeffrey W.; White, Stephen M.
We obtained coordinated observations of the large sunspot in NOAA Region 8539 on 1999 May 9 and 13 with the Very Large Array and three instruments (CDS, EIT, MDI) aboard the Solar and Heliospheric Observatory satellite. The EUV observations reveal a plume in the sunspot umbra on both observing dates. The plume appears brightest in emission lines f…
Simultaneous Velocity-Intensity Spectral and Cross-Spectral Fitting of Helioseismic Data
Hill, F.; Barban, C.; Kras, S.
Solar oscillation parameters, such as the frequency, are usually estimated by fitting the mode profile in the velocity (V) power spectrum. In this paper, the solar oscillation parameters are derived by simultaneously fitting four observational spectra: V and I (intensity) power, I-V phase difference, and I-V coherence using the model of Severino e…
The Ofpe/WN9 Stars in M33
Massey, Philip; Bianchi, Luciana; Bohlin, Ralph
We present Hubble Space Telescope/STIS Ultraviolet spectra of the six known Ofpe/WN9 stars (``slash stars'') in M33. These stars were selected for showing the characteristics of the Ofpe/WN9 class from previous optical ground-based spectroscopy. The UV spectra are rich in wind lines whose strength and terminal velocity vary greatly across our targ…