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The Cluster Magnetic Field Investigation

Balogh, A.; Buchert, S.; Dunlop, M. W. +12 more

Cross-correlation characteristics of OB stars from IUE spectroscopy

Howarth, Ian D.; Prinja, Raman K.; Siebert, Kaj W. +1 more

We present a catalogue of homogeneous measures of the linewidth parameter, v_esin i, for 373 O-type stars and early B supergiants (including the separate components of 25 binary and three triple systems), produced by cross-correlating high-resolution, short-wavelength IUE spectra against a `template' spectrum of tauSco. We also tabulate terminal v…

LBDS 53W091: An Old, Red Galaxy at z = 1.552

Windhorst, Rogier; Dey, Arjun; Spinrad, Hyron +4 more

The weak radio source LBDS 53W091 is associated with a very faint (R ~ 24.5) red (R - K ~ 5.8) galaxy. Long spectroscopic integrations with the W. M. Keck telescope have provided an absorption-line redshift, z = 1.552 +/- 0.002. The galaxy has a rest frame ultraviolet spectrum very similar to that of an F6 V star, and a single-burst old stellar po…

Sustaining the Quiet Photospheric Network: The Balance of Flux Emergence, Fragmentation, Merging, and Cancellation

Shine, Richard A.; Title, Alan M.; Schrijver, Carolus J. +2 more

The magnetic field in the solar photosphere evolves as flux concentrations fragment in response to sheared flows, merge when they collide with others of equal polarity, or (partially) cancel against concentrations of opposite polarity. Newly emerging flux replaces the canceled flux. We present a quantitative statistical model that is consistent wi…

EIT Observations of the Extreme Ultraviolet Sun

Michels, D. J.; Gurman, J. B.; Berghmans, D. +32 more

The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft has been operational since 2 January 1996. EIT observes the Sun over a 45 x 45 arc min field of view in four emission line groups: Feix, x, Fexii, Fexv, and Heii. A post-launch determination of the instrument flatfield, the instrument scattering function, and the instrume…

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…