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Keck HIRES Spectroscopy of M92 Subgiants: Surprising Abundances near the Turnoff
King, Jeremy R.; Boesgaard, Ann M.; Stephens, Alex +1 more
Using high-resolution, moderate signal-to-noise ratio spectroscopy obtained with the 10 m Keck I Telescope and efficient HIRES echelle spectrograph, we derive abundances of several elements in subgiants near the M92 turnoff. As a consistency check, we also analyze the metal-poor field star HD 140283 and find an Fe abundance in fine agreement with …
Early Evolution of the Galactic Halo Revealed from Hipparcos Observations of Metal-poor Stars
Yoshii, Yuzuru; Chiba, Masashi
The kinematics of 122 red giant and 124 RR Lyrae stars in the solar neighborhood are studied using accurate measurements of their proper motions obtained by the Hipparcos astrometry satellite, combined with their published photometric distances, metal abundances, and radial velocities. A majority of these sample stars have metal abundances of [Fe/…
Solar Active Region and Quiet-Sun Extreme-Ultraviolet Spectra from SERTS-95
Brosius, Jeffrey W.; Thomas, Roger J.; Davila, Joseph M.
Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph was flown on 1995 May 15 (SERTS-95), carrying a multilayer-coated toroidal diffraction grating that enhanced the instrumental sensitivity in its second-order wave band (171-225 Å). Spectra and spectroheliograms of NOAA active region 7870 (N09 W22) were obtained in this wave …
Spatially Resolved STIS Spectroscopy of SN 1987A: Evidence for Shock Interaction with Circumstellar Gas
Lundqvist, P.; Gull, T. R.; McCray, R. +15 more
Visual and ultraviolet spatially resolved (~0.1") spectra of SN 1987A obtained on days 3715 and 3743 with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope show that the high-velocity supernova debris is colliding with circumstellar gas. Very broad Lyα emission with velocities extending to ~+/-20,000 km s-1 originat…
EUV97: Improvements to EUV Irradiance Modeling in the Soft X-Rays and FUV
Tobiska, W. Kent; Eparvier, F. G.
EUV97 is a solar EUV empirical model that incorporates revised soft X-ray fluxes from the SOLRAD-11 satellite (1976-1979) and uses Lα recently recalibrated to the UARS satellite (1991-present) SOLSTICE Lα. The soft X-ray data have been revised from the original flux values using Mewe's spectral fits to the data. The recalibrated AE-E and SME Lα da…
Faint [O iv] emission from starburst galaxies
Lutz, D.; Kunze, D.; Spoon, H. W. W. +1 more
We report the detection of faint emission in the high-excitation [O iv] 25.90mu m line in a number of starburst galaxies, from observations obtained with the Short Wavelength Spectrometer (SWS) on board ISO. Further observations of M 82 spatially resolve the [O iv] emitting region. Detection of this line in starbursts is surprising since it is not…
The distances to the X-ray binaries LSI +61 deg 303 and A0535+262
Coe, M. J.; Steele, I. A.; Negueruela, I. +1 more
Chevalier & Ilovaisky use Hipparcos data to show that the X-ray binary systems LSI+61 deg 303 and A0535+262 are a factor of 10 closer (i.e. d~ few hundred pc) than previously thought (d~kpc). We present high-quality CCD spectra of the systems, and conclude that the spectral types, reddening and absolute magnitudes of these objects are strongly…
Time Variability of Active Region Loops Observed with the Coronal Diagnostic Spectrometer (Cds) on SOHO
Kjeldseth-Moe, O.; Brekke, P.
Monochromatic images from the Coronal Diagnostic Spectrometer (CDS) of loops above active regions show clear evidence of rapid time variability. The rapidly changing conditions that we observe give a new conception of loop systems that has never before been seriously considered. Loop systems, particularly in emission lines formed at temperatures i…
Hubble Space Telescope Observations of the Draco Dwarf Spheroidal Galaxy
Ballester, Gilda E.; Crisp, David; Grillmair, Carl J. +15 more
We present an F606W-F814W color-magnitude diagram for the Draco dwarf spheroidal galaxy based on Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) images. The luminosity function is well sampled to ~3 mag below the turnoff. We see no evidence for multiple turnoffs and conclude that, at least over the field of view of the WFPC2, star for…
The nature of the cometary knots in the Helix planetary nebula (NGC7293)
Walsh, J. R.; Steffen, W.; Meaburn, J. +3 more
The system of cometary knots in the Helix planetary nebula (NGC7293) has been systematically observed using ground-based images and long-slit, high-resolution spectroscopy. CCD images in the [Nii] 6584-A line, taken with the ESO NTT, are used to determine the spatial distribution of the knots; images in the [Oiii] 5007-A line distinguish their pos…