Search Publications
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…
Far-Ultraviolet Spectra of Starburst Galaxies: Stellar Population and the Kinematics of the Interstellar Medium
Ferguson, Henry C.; Robert, Carmelle; Heckman, Timothy +3 more
The far-ultraviolet spectra of the four starburst galaxies NGC 6090, Mrk 66, Mrk 1267, and IRAS 0833+6517 were observed with the Hopkins Ultraviolet Telescope during the Astro-2 mission. Additional data were obtained for IRAS 0833+6517 with the Goddard High-Resolution Spectrograph (GHRS) on the Hubble Space Telescope. We analyze the observations i…
Measurements of Solar Magnetic Element Dispersal
Berger, Thomas E.; Shine, Richard A.; Title, Alan M. +1 more
The dispersal of magnetic elements in the solar photospheric flow field is studied by tracking individual ``magnetic bright points'' (MBPs) identified in a G-band 4305 Å filtergram time series obtained at the 50 cm Swedish Vacuum Solar Telescope on La Palma, Spain. The time series spans approximately 70 minutes with a field of view of 29" × 29" ne…
A Wide Field Planetary Camera 2 Study of the Resolved Stellar Population of the Pegasus Dwarf Irregular Galaxy (DDO 216)
Saha, A.; Mateo, M.; Gallagher, J. S. +5 more
The stellar population of the Pegasus dwarf irregular galaxy is investigated in images taken in the F439W (B), F555W (V), and F814W (I) bands with the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope. With WFPC2 the Pegasus dwarf is highly resolved into individual stars to limiting magnitudes of about 25.5 in B and V and 25 in I…
IRAS 23385+6053: A Prototype Massive Class 0 Object
Testi, Leonardo; Molinari, Sergio; Brand, Jan +2 more
IRAS 23385+6053 is a young stellar object with a luminosity of ~1.6×104 Lsolar at a kinematic distance of 4.9 kpc. This candidate precursor of an ultracompact H II region is associated with a millimeter source detected at the James Clerk Maxwell Telescope but is undetected at centimeter wavelengths with the VLA. We observed t…