Search Publications
The Complex Protostellar Source IRAS 04325+2402
Hartmann, Lee; Calvet, Nuria; Jayawardhana, Ray +2 more
We report Hubble Space Telescope near-infrared NICMOS observations of a remarkable low-luminosity Class I (protostellar) source in the Taurus Molecular Cloud. IRAS 04325+2402 exhibits a complex bipolar scattered light nebula. The central continuum source is resolved and may be multiple, or it may be crossed by a small dust lane. Complex arcs seen …
The Perseus B5 Molecular Cloud Halo: Measurements of Pressure, Temperature, and Composition
Andersson, B. -G.; Federman, S. R.; Wannier, Peter +1 more
We present GHRS observations of interstellar C I and CO toward three stars located in the direction of the Perseus region near the B5 molecular cloud and discuss these together with published results from a fourth sight line. The column densities of the three fine-structure levels of C I are used together with ground-based optical data and publish…
A Study of Microwave-selected Coronal Transient Brightenings
Nindos, A.; Kundu, M. R.; White, S. M.
We present the results of a search for radio-selected transient brightenings (TBs) in the solar atmosphere as a complement to the more common X-ray-selected surveys. The Sun was generally quiet during the observations, making these data sensitive to weak TBs both in and outside active regions. Five small impulsive events were identified in a set o…
Polarized Narrow-Line Emission from the Nucleus of NGC 4258
Filippenko, Alexei V.; Ho, Luis C.; Barth, Aaron J. +5 more
The detection of polarized continuum and line emission from the nucleus of NGC 4258 by Wilkes et al. in 1995 provides an intriguing application of the unified model of Seyfert nuclei to a galaxy in which there is known to be an edge-on, rotating disk of molecular gas surrounding the nucleus. Unlike most Seyfert nuclei, however, NGC 4258 has strong…
Isotopic composition of HG and Pt in 5 slowly rotating HgMn stars
Hubrig, S.; Castelli, F.; Mathys, G.
Theoretical models addressing the origin of peculiarities in the spectra of HgMn stars have not been sufficiently constrained so far by the available abundance data. Previous studies of Hg and Pt in samples of HgMn stars often relied on spectra of rather low resolution and low S/N ratio, so that only limited information could be derived from the c…
Infrared Spectroscopy of NGC 4151: Infrared Space Observatory Observations and Narrow Emission Line Region Line Profiles
Lutz, D.; Genzel, R.; Sturm, E. +3 more
We present Infrared Space Observatory (ISO) Short-Wavelength Spectrometer (SWS) and ISOPHOT-S spectroscopy4 of the Seyfert galaxy NGC 4151. We detect a total of 17 fine-structure emission lines emitted by a wide range of low- and high-excitation ions, two rotational lines of molecular hydrogen, and the Brβ H I line. We find that the mid-IR fine-st…
The Kinematics of Stars Emerging from Expanding Shells: An Analysis of the Gould Belt
Moreno, Edmundo; Alfaro, Emilio J.; Franco, José
Using the available data for nearby stars from the Hipparcos catalog, we derive the velocity ellipsoid of dwarf O-B5.5 stars belonging to the Gould Belt (GB). The resulting vertex deviation for the whole sample of 252 stars is lv~-64deg+/-20deg, and this value is modified to lv=22deg+/-8d…
High-Frequency and High-Wavenumber Solar Oscillations
Basu, Sarbani; Antia, H. M.
We determine the frequencies of solar oscillations covering a wide range of degree (100<l<4000) and frequency (1.5<ν<10 mHz) using the ring diagram technique applied to power spectra obtained from Michelson Doppler Imager (MDI) data. The f-mode ridge extends up to l~3000, where the line width becomes very large, which implies a damping…
The global nature of solar cycle variations of the solar wind dynamic pressure
Wang, Chi; Richardson, John
The solar wind dynamic pressure measured near the ecliptic varies over the solar cycle. A major unanswered question has been whether this variation is a global feature or restricted to low latitudes and thus perhaps a consequence of the changing heliospheric current sheet configuration. We use plasma data from IMP-8, Ulysses and Voyager 2 to show …
Deep Near-Infrared Images and ISOCAM Observations of Chamaeleon I North
Olofsson, G.; Roth, M.; Nordh, L. +3 more
We present the results of deep near-infrared imaging and ISOCAM observations of three selected regions localized in the northern part of the Chamaeleon I dark cloud, in order to search for the low-luminosity population. In an area of 3x3 arcmin^2 centered on the bipolar molecular outflow, which is the densest part of the cloud, we have discovered …