Search Publications
The Hubble Space Telescope Extragalactic Distance Scale Key Project. IX. The Discovery of Cepheids in NGC 2090
Illingworth, Garth D.; Huchra, John P.; Kennicutt, Robert C. +15 more
We report on the discovery of 34 Cepheid variables in NGC 2090, with periods ranging between 5 and 58 days. Apparent V and I period-luminosity relations for Cepheids with P >= 10 days have been constructed, assuming a fiducial distance modulus, µ0, of 18.50 +/- 0.10 mag and a reddening, E(B-V), of 0.10 mag for the Large Magella…
High-Resolution Mid-Infrared Imaging of the Nucleus of NGC 1068
Bock, J. J.; Marsh, K. A.; Ressler, M. E. +1 more
We have obtained mid-infrared images of the nucleus of NGC 1068 from the Hale 5 m telescope at Mount Palomar with diffraction-limited resolution and high sensitivity at λ=8.8, 10.3, and 12.5 µm. Deconvolved images show that the infrared emission extends north to south in the inner 2", consisting of a central peak, a component extending 1" no…
Absolute Vacuum Ultraviolet Oscillator Strengths in CO II and the Interstellar Cobalt Abundance
Federman, S. R.; Lawler, J. E.; Mullman, K. L. +1 more
We report the first laboratory measurements of 10 absolute oscillator strengths (f-values) for vacuum ultraviolet lines of Co II. The oscillator strengths are measured with the High-Sensitivity Absorption Spectroscopy Experiment at the University of Wisconsin. The measurements serve as a test of theoretical work on Co II f-values and set an absolu…
Hubble Space Telescope Observations of NGC 121: First Detection of Blue Stragglers in an Extragalactic Globular Cluster
Fall, S. Michael; Rich, R. Michael; Shara, Michael M. +1 more
We have resolved stars in the core of the old SMC globular cluster NGC 121 with images from the refurbished Hubble Space Telescope and Wide Field Planetary Camera 2. Our photometry reaches 1.5 mag below the main-sequence turnoff, with negligible field contamination. A blue straggler star (BSS) sequence of 42 candidates is clearly seen--the first s…
High-Metallicity Mg II Absorbers in the z < 1 Lyα Forest of PKS 0454+039: Giant Low Surface Brightness Galaxies?
Churchill, Christopher W.; Le Brun, Vincent
We report the discovery of two iron-group enhanced high-metallicity Mg II absorbers in a search through 28 Lyα forest clouds along the PKS 0454+039 sight line. Based upon our survey and the measured redshift number densities of Wr(Mg II) <= 0.3 Å absorbers and Lyα absorbers at z ~ 1, we suggest that roughly 5% of Lyα absorbers at z &…
Spatial Gradients and the Volumetric Tensor
Harvey, Christopher C.
Preliminary retrieval of solar wind latitude distribution from Solar Wind Anisotropies/SOHO observations
Schmidt, W.; Quemerais, E.; Bertaux, J. -L. +5 more
The Solar Wind Anisotropies (SWAN) instrument on board the SOHO spacecraft measures Lyman alpha radiation emanating mainly from neutral hydrogen gas in the solar neighborhood. This gas is part of the local interstellar cloud in which the Sun and the heliosphere are immersed. Measurements of Lyman alpha can be used to infer the local cloud characte…
Heating and acceleration of minor ions in the solar wind
McKenzie, J. F.; Czechowski, A.; Axford, W. I. +1 more
We make use of the results of a one-ion model of McKenzie et al. (1997) to obtain the critical solution describing the acceleration of a two-ion solar wind. The model includes preferential heating of the heavy ion species and the temperature anisotropy expected if the heating is predominantly due to ion-cyclotron damping. The relationship of the m…
A ring of organic molecules around HD 97300
Prusti, T.; Siebenmorgen, R.; Natta, A. +1 more
This paper presents spectro-photometric images of the pre-main-sequence Herbig AeBe star HD 97300 in the mid-IR obtained with ISOCAM on board of ISO. The images show extended emission, an elliptical ring structure of size about 0.045x0.03 pc as well as two peaks of emission, separated by about 3arcsec (240 AU). One of the two peaks coincides with …
Behaviour of calcium abundance in Am-Fm stars with evolution
North, P.; Kunzli, M.
Calcium abundance in the atmosphere of Am stars is examined as a function of their evolutionary state within the main sequence. New spectroscopic abundances as well as abundances obtained photometrically by Guthrie (1987) are used, since they are mutually quite consistent. The main result of this work is that, contrary to earlier suggestions, calc…