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Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory
Bagnuolo, William G., Jr.; Mason, Brian D.; ten Brummelaar, Theo +4 more
We present photometric and astrometric results for 36 binary systems observed with the natural guide star adaptive optics system of the Mount Wilson Institute on the 100 inch (2.5 m) Hooker Telescope. The measurements consist of differential photometry in U, B, V, R, and I filters along with astrometry of the relative positions of system component…
Far infrared mapping of the gas cooling along the L1448 outflow
Codella, C.; Benedettini, M.; Lorenzetti, D. +4 more
The molecular outflows associated with the two Class 0 sources L1448-mm and L1448-IRS3 have been mapped with the spectrometers on board the ISO satellite allowing to study in detail the physical and chemical structure of the shocked gas. The far infrared cooling is mainly due to the emission from pure rotational lines of CO, H2O and H
Multi-colour PL-relations of Cepheids in the bt HIPPARCOS catalogue and the distance to the LMC
Groenewegen, M. A. T.; Oudmaijer, R. D.
We analyse a sample of 236 Cepheids from the hipparcos catalog, using the method of ``reduced parallaxes'' in V, I, K and the reddening-free ``Wesenheit-index''. We compare our sample to those considered by Feast & Catchpole (1997) and Lanoix et al. (1999), and argue that our sample is the most carefully selected one with respect to completene…
Non-LTE analysis of neutral magnesium in cool stars
Zhao, G.; Gehren, T.
Calculations of the statistical equilibrium of magnesium in the solar photosphere have shown that NLTE populations hardly affect Mg line formation in the Sun. However, in metal-poor dwarfs and giants the influence of electron collisions is reduced, and the ultraviolet radiation field, enhanced due to reduced background line opacity, results in mor…
LINER/HII ``Transition'' Nuclei and the Nature of NGC 4569
Shields, Joseph C.; Barth, Aaron J.
Motivated by the discovery of young, massive stars in the nuclei of some LINER/H II ``transition'' nuclei such as NGC 4569, we have computed photoionization models to determine whether some of these objects may be powered solely by young star clusters rather than by accretion-powered active nuclei. The models were calculated with the photoionizati…
On the Constancy of the Solar Diameter
Kuhn, J. R.; Bush, R. I.; Emilio, M. +1 more
Why does the solar luminosity vary and could it change on human timescales by enough to affect terrestrial climate? As important as these questions are, we lack answers because we do not understand the physical mechanisms responsible for the solar irradiance cycle. Progress here depends on discovering how changes in the solar interior affect energ…
Development of Coronal Mass Ejections: Radio Shock Signatures
Vourlidas, Angelos; Howard, Russel; Pick, Monique +1 more
We present observational imaging evidence for the existence of metric radio bursts closely associated with the front edge of coronal mass ejections (CMEs). These radio bursts drift in frequency similarly to type II bursts. They are weak and usually go undetected on spectrograph data. We find the same measured projected velocity for the displacemen…
The European Large Area ISO Survey - III. 90-µm extragalactic source counts
Genzel, R.; Danese, L.; Puget, J. -L. +17 more
We present results and source counts at 90µm extracted from the preliminary analysis of the European Large Area ISO Survey (ELAIS). The survey covered about 12deg2 of the sky in four main areas and was carried out with the ISOPHOT instrument onboard the Infrared Space Observatory (ISO). The survey is at least an order of magnitude…
Monte Carlo predictions of far-infrared emission from spiral galaxies
Bianchi, S.; Davies, J. I.; Alton, P. B.
We present simulations of Far Infrared (FIR) emission by dust in spiral galaxies, based on the Monte Carlo radiative transfer code of \citet*{BianchiApJ1996}. The radiative transfer is carried out at several wavelength in the Ultraviolet (UV), optical and Near Infrared (NIR), to cover the range of the stellar Spectral Energy Distribution (SED). To…
Stellar dynamics observations of a double nucleus in M 83
Genzel, R.; Thatte, N.; Tecza, M.
We report on the discovery of a double nucleus in M 83, based on measurements of the line of sight velocity distribution of stars observed at near infrared wavelengths with the VLT ISAAC spectrograph. We observe two peaks separated by 2\farcs 7 in the velocity dispersion profile of light from late-type stars measured along a slit 0\farcs 6 wide, c…