Search Publications
Radiometric calibration of the telescope and ultraviolet spectrometer SUMER on SOHO
Wilhelm, Klaus; Schühle, Udo; Curdt, Werner +4 more
The prelaunch spectral-sensitivity calibration of the solar spectrometer SUMER (Solar Ultraviolet Measurements of Emitted Radiation) is described. SUMER is part of the payload of the Solar and Heliospheric Observatory (SOHO), which begins its scientific mission in 1996. The instrument consists of a telescope and a spectrometer capable of taking sp…
High resolution UV spectroscopy of two hot (pre-) white dwarfs with the Hubble Space Telescope. KPD0005+5106 and RXJ2117+3412.
Rauch, T.; Werner, K.; Dreizler, S. +4 more
High resolution UV spectra of KPD0005+5106 and RXJ2117+3412 have been obtained with the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope. The data were subject to a non-LTE model atmosphere analysis. For KPD0005+5106, the hottest known helium-rich white dwarf, the C and N abundances as well as an upper limit for O have been d…
In Situ Measurements of Interstellar Dust with the ULYSSES and Galileo Spaceprobes
Grün, Eberhard; Landgraf, Markus; Baguhl, Michael
Interstellar dust was first identified by the dust sensor onboard Ulysses after the Jupiter flyby in February 1992. These findings were confirmed by the Galileo experiment on its outbound orbit from Earth to Jupiter. Although modeling results show that interstellar dust is also present at the Earth orbit, a direct identification of interstellar gr…
Hubble Space Telescope Observations of Globular Clusters in M31. II. Structural Parameters
Holtzman, J. A.; Faber, S. M.; Grillmair, C. J. +5 more
We analyze post-refurbishment Hubble Space Telescope images of four globular clusters in M31. The ability to resolve stars to below the horizontal branch permits us to use star counts to extend the surface brightness profiles determined using aperture photometry to almost 5 orders of magnitude below the central surface density. Three of the result…
ISOCAM mapping of the Whirlpool galaxy M51.
Elbaz, D.; Boulanger, F.; Okumura, K. +13 more
We have obtained the first images of the 6.75 and 15µm continuum emission in the Whirlpool galaxy with ISOCAM, the infrared camera of the ISO (Kesslet et al., 1996A&A...315L..27K). These data reveal the well-developed, spiral arms of the galaxy, in addition to diffuse emission between arms and in the outer regions of the disk. There is a…
Observations of Saturn's Inner Satellites During the May 1995 Ring-Plane Crossing
Bosh, Amanda S.; Rivkin, Andrew S.
The 22 May 1995 Saturn ring-plane crossing was observed with the Hubble Space Telescope; the markedly reduced scattered light from the rings at this time allowed study of the small inner satellites of the Saturn system. Prometheus was further from its predicted location than expected based on uncertainties in the 1981 ephemerides propagated forwar…
Keck Spectroscopy and Hubble Space Telescope Imaging of Field Galaxies at Moderate Redshift
Illingworth, Garth D.; Forbes, Duncan A.; Koo, David C. +1 more
We present 18 spectra, obtained with the Keck 10 m telescope, of faint field galaxies (19 <I < 22, 0.2 < z < 0.84) previously imaged by the Hubble Space Telescope (HST) Wide Field and Planetary Camera 2 (WFPC2). Though small, our sample appears to be representative of field spirals with a magnitude limit of I <= 22. Combining the re…
Properties of arc-polarized Alfvén waves in the ecliptic plane: Ulysses observations
Balogh, A.; Tsurutani, B. T.; Forsyth, R. J. +3 more
Ulysses observations of the interplanetary magnetic field reveal well-ordered rotations on the timescale of several hours. These have been previously identified as ``arc-polarized'' Alfvén waves. Rotational discontinuities (RDs) are often an integral part of the wave. This study focuses on a statistical description of these rotations (ARCs) in the…
Spectroscopic study of the outflowing disk winds of B[e] supergiants in the Magellanic Clouds.
Stahl, O.; Humphreys, R. M.; Zickgraf, F. -J. +3 more
We report on UV high resolution spectroscopic observations of R50 in the Small Magellanic Cloud, and R82 and HenS22 in the Large Magellanic Cloud obtained with the International Ultraviolet Explorer. The observed stars are supposed to represent edge-on cases of B[e] supergiants for which a two-component stellar wind model has previously been sugge…
Are Hubble Deep Field Galaxy Counts Whole Numbers?
Spergel, David N.; Ostriker, Jeremiah P.; Rhoads, James E. +1 more
The Hubble Deep Field (HDF) offers the best view to date of the optical sky at faint magnitudes and small angular scales. Early reports suggested that faint source counts continue to rise to the completeness limit of the data, which implies a very large number of galaxies. In this Letter, we use the two-point angular correlation function and numbe…