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HIPPARCOS Period-Luminosity Relations for Mira and Semiregular variables
Bedding, Timothy R.; Zijlstra, Albert A.
We present period-luminosity (P-L) diagrams for nearby Mira and semiregular variables, selecting stars with parallaxes better than 20% and well-determined periods. Using K-band magnitudes, we find two well-defined P-L sequences, one corresponding to the standard Mira P-L relation and the second shifted to shorter periods by a factor of about 1.9. …
Gas Cloud Kinematics near the Nucleus of NGC 4151
Gull, T. R.; Kraemer, S. B.; Crenshaw, D. M. +10 more
We report early observations with Space Telescope Imaging Spectrometer (STIS) of the nuclear region of NGC 4151. Direct images in [O II] and [O III] and slitless medium-dispersion spectral images of the Hβ to [O III] region were obtained. A slitless UV spectral image was taken of the C IV 1550 Å region. We present radial velocities and line ratios…
Detection of 55-80 keV Hydrogen Atoms of Heliospheric Origin by CELIAS/HSTOF on SOHO
Livi, S.; Hsieh, K. C.; Wurz, P. +29 more
The High-Energy Suprathermal Time-of-Flight sensor (HSTOF) of the Charge, Element, and Isotope Analysis System (CELIAS) on the Solar and Heliospheric Observatory (SOHO) near the Lagrangian point L1 is capable of identifying energetic hydrogen atoms (EHAs) between 55 and 80 keV. Between 1996 February 13 and 1997 August 31, near solar minimum, there…
An Empirical Isochrone of Very Massive Stars in R136a
Hubeny, Ivan; Heap, Sara R.; de Koter, Alex
We report on a detailed spectroscopic study of 12 very massive and luminous stars (M >~ 35M⊙) in the core of the compact cluster R136a, near the center of the 30 Doradus complex. The three brightest stars of the cluster, R136a1, R136a2, and R136a3, have been investigated earlier by de Koter, Heap, & Hubeny. Low-resolution spectra…
Cloning Hubble Deep Fields. I. A Model-independent Measurement of Galaxy Evolution
Broadhurst, Tom; Bouwens, Rychard; Silk, Joseph
We present a model-independent method of quantifying galaxy evolution in high-resolution images, a method which we apply to the Hubble Deep Field (HDF). Our procedure is to k-correct all pixels belonging to the images of a complete set of bright galaxies and then to replicate each galaxy image to higher redshift by the product of its space density…
On the use of the HIPPARCOS intermediate astrometric data
Evans, D. W.; van Leeuwen, F.
With the publication of the Hipparcos catalogue, astrometric data of unprecedented quality and quantity has become available, providing parallaxes, positions and proper motions free from systematic errors down to a level of at least 0.1 mas and 0.1 mas y(-1) . The Hipparcos catalogue, however, contains not only these ``ready-to-use'' positions, pa…
Discovery of CO_2 emission in AGB stars with the 13mu M dust feature
Waters, L. B. F. M.; Feuchtgruber, H.; Justtanont, K. +4 more
We have detected strong emission lines at 13.48, 13.87, 14.97, 15.40 and 16.28mu m in the ISO/SWS spectra of O-rich AGB stars. These lines are only found in the spectra of Miras and semi-regular variables when they also show the 13mu m dust emission feature. The lines appear just resolved in the high-resolution (AOT06, resolution ~ 1500) SWS spect…
The Morphology and Kinematics of the Complex Polypolar Planetary Nebula NGC 2440
López, J. A.; Meaburn, J.; Holloway, A. J. +1 more
Spatially resolved profiles of the Hα, [N II] 6584 Å, and [O III] 5007 Å lines have been obtained with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Mártir telescope over the planetary nebula NGC 2440. The resulting position-velocity (PV) arrays are compared with ground-based and HST archival imagery, revealing the complex …
Discovery of Red Selected Arcs at Z = 4.04 behind Abell 2390
Broadhurst, Tom; Frye, Brenda
We describe the properties of three red arcs discovered at z=4.04 behind the cluster A2390 (z=0.23). We demonstrate that these arcs are images of a single galaxy where lensing is compounded by an elliptical cluster member near the critical curve of the cluster. The combined magnification is estimated to be ~20 using Hubble Space Telescope images, …
Coronal line-width variations
Doyle, J. G.; Banerjee, D.; Perez, M. E.
Line-width measurements of the coronal ion Siviii confirm earlier observations which show an increase in the non-thermal velocity above the solar limb. The present data, taken at the equatorial limb, show an increase from 24 km s-1 at the limb to 28 km s-1 some 25000 km above the limb. The electron density as measured from th…