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The Panchromatic Starburst Intensity Limit at Low and High Redshift
Lehnert, Matthew D.; Heckman, Timothy M.; Meurer, Gerhardt R. +2 more
The integrated bolometric effective surface brightness S_e distributions of starburst are investigated for samples observed in 1. the rest frame ultraviolet (UV), 2. the far-infrared and \Hα, and 3. 21cm radio continuum emission. For the UV sample we exploit a tight empirical relationship between UV reddening and extinction to recover the bolometr…
M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale
Gizis, John E.
We present a spectroscopic classification system for M-dwarfs and M-subdwarfs based on quantitative measures of TiO and CaH features in the region lambda lambda 6200 - 7400 Angstroms. Our sample of cool stars covers the range from solar metallicity stars to the most extreme subdwarfs known. Using synthetic spectra computed by Allard and Hauschildt…
Ages of Globular Clusters from HIPPARCOS Parallaxes of Local Subdwarfs
Fusi Pecci, Flavio; Carretta, Eugenio; Clementini, Gisella +3 more
We report here initial but strongly conclusive results for absolute ages of Galactic globular clusters (GGCs). This study is based on high-precision trigonometric parallaxes from the HIPPARCOS satellite coupled with accurate metal abundances ([Fe/H], [O/Fe], and [α/Fe]) from high-resolution spectroscopy for a sample of about thirty subdwarfs. Syst…
First Results of the SUMER Telescope and Spectrometer on SOHO - I. Spectra and Spectroradiometry
Vial, J. -C.; Grewing, M.; Wilhelm, K. +16 more
SUMER - the Solar Ultraviolet Measurements of the Emitted Radiation instrument on the Solar and Heliospheric Observatory (SOHO) - observed its first light on January 24, 1996, and subsequently obtained a detailed spectrum with detector B in the wavelength range from 660 to 1490 Å (in first order) inside and above the limb in the north polar corona…
Galactic kinematics of Cepheids from HIPPARCOS proper motions
Feast, Michael; Whitelock, Patricia
The Hipparcos proper motions of 220 Galactic Cepheids, together with relevant ground-based photometry, have been analysed. The effects of Galactic rotation are very clearly seen. Mean values of the Oort constants, A=14.82+/-0.84 km s^-1 kpc^-1, and B=-12.37+/-0.64 km s^-1 kpc^-1, and of the angular velocity of circular rotation at the Sun, Omega_o…
Composition of Coronal Streamers from the SOHO Ultraviolet Coronagraph Spectrometer
Romoli, M.; Raymond, J. C.; Naletto, G. +24 more
The Ultraviolet Coronagraph Spectrometer on the SOHO satellite covers the 940-1350 Å range as well as the 470-630 Å range in second order. It has detected coronal emission lines of H, N, O, Mg, Al, Si, S, Ar, Ca, Fe, and Ni, particularly in coronal streamers. Resonance scattering of emission lines from the solar disk dominates the intensities of a…
Low-Mass Binaries and the Stellar Luminosity Function
Gizis, John E.; Reid, I. Neill
We present a new investigation of the influence of unresolved binaries on the form deduced for the stellar luminosity function from photometric parallax surveys. We have compiled a catalogue of photometry and binary statistics for stars known to be north of -30° declination and within 8 parsecs of the Sun, and have used these stars as a reference …
Interstellar Abundance Gradients in NGC 2403: Comparison to M33
Garnett, D. R.; Skillman, E. D.; Dufour, R. J. +2 more
We present new long-slit spectra of 12 H II regions in the Scd spiral galaxy NGC 2403. Gas-phase element abundances for O, N, S, Ne, and Ar were estimated using direct measurements of electron temperature based on detections of [O III] λ4363, [S III] λ6312, and [O II] λ7320-7330, and from theoretical photoionization analysis. We find abundance gra…
Impact excavation on asteroid 4 Vesta: Hubble Space Telescope results
Binzel, R. P.; Thomas, P. C.; Storrs, A. D. +3 more
A Pair of Lensed Galaxies at z = 4.92 in the Field of CL 1358+62
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +2 more
The cluster CL 1358+62 displays a prominent red arc in WFPC2 images obtained with the Hubble Space Telescope. Keck spectra of the arc show Lyα emission at 7204 Å, a continuum drop blueward of the line, and several absorption lines to the red. We identify the arc as a gravitationally lensed galaxy at a redshift of z = 4.92. It is the highest redshi…