Search Publications
Hubble Space Telescope Observations of the Gravitationally Lensed Cloverleaf Broad Absorption Line QSO H1413+1143: Imaging Polarimetry and Evidence for Microlensing of a Scattering Region
Turnshek, David A.; Rao, Sandhya M.; Schulte-Ladbeck, Regina E. +2 more
We report the results of Hubble Space Telescope Wide Field and Planetary Camera 2 broadband F555W and F702W photometric and F555W polarimetric observations of the ``Cloverleaf'' QSO H1413+1143. This is a four-component gravitationally-lensed broad absorption line (BAL) QSO. Observations were obtained at two epochs in 1999 March and 1999 June separ…
Dynamical Cycles in Charge and Energy for Iron Ions Accelerated in a Hot Plasma
Torsti, J.; Kocharov, L.; Kovaltsov, G. A.
We consider a unified model of Fe ion acceleration in the solar corona. The model comprises charge-changing processes, Coulomb energy losses, and both regular and stochastic acceleration. At a given acceleration scenario, the type of acceleration is found to have a minor effect on the mean charge states, but the shapes of the charge-state distribu…
HST/STIS spectroscopy of the exposed white dwarf in the short-period dwarf nova EK TrA
Gänsicke, B. T.; Szkody, P.; Hoard, D. W. +4 more
We present high resolution Hubble Space Telescope ultraviolet spectroscopy of the dwarf nova EK TrA obtained in deep quiescence. The Space Telescope Imaging Spectrograph data reveal the broad Lyalpha absorption profile typical of a moderately cool white dwarf, overlayed by numerous broad emission lines of He, C, N, and Si and by a number of narrow…
A Comparison between PAα and Hα Emission: The Relation between Mean H II Region Reddening, Local Gas Density, and Metallicity
Quillen, Alice C.; Yukita, Mihoko
We measure reddenings to H II regions in NGC 1512, 2903, 4449, and 6946, and M51 from Hubble Space Telescope (HST) Paα and Hα images. Extinctions range from AV~5 to 0 depending upon the galaxy. For the galaxies with HST images in both lines, NGC 1512, NGC 2903, and M51, the Paα and Hα emission are almost identical in morphology, which i…
FIRBACK. II. Data reduction and calibration of the 170 µ m ISO deep cosmological survey
Dole, H.; Lagache, G.
We present the final reduction and calibration of the FIRBACK ISOPHOT data. FIRBACK is a deep cosmological survey performed at 170 mu m. This paper deals with the ISOPHOT C200 camera with the C160 filter. We review the whole data reduction process and compare our final calibration with DIRBE (for the extended emission) and IRAS (for point sources)…
Intercalibration of SUMER and CDS on SOHO. II. SUMER detectors A and B and CDS NIS
Solanki, Sami K.; Wilhelm, Klaus; Schühle, Udo +5 more
Results of an intercalibration between the extreme-ultraviolet spectrometers Coronal Diagnostic Spectrometer (CDS) and Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on board the Solar and Heliospheric Observatory (SOHO) are reported. The results of the joint observing program Intercal_01 are described, and intercalibration results up…
HST/STIS observations of the high-velocity interstellar cloud HVC 291.2-41.2+80: a warm, mainly ionized high-velocity cloud
Sembach, K. R.; Keenan, F. P.; Lehner, N.
We present intermediate-resolution HST/STIS spectra of a high-velocity interstellar cloud (vLSR=+80kms-1) towards DI1388, a young star in the Magellanic Bridge located between the Small and Large Magellanic Clouds. The STIS data have a signal-to-noise ratio (S/N) of 20-45 and a spectral resolution of about 6.5kms-1…
Photometric properties of the Arp 220 super star clusters
Taniguchi, Yoshiaki; Shioya, Yasuhiro; Trentham, Neil
We investigate the photometric properties of six super stellar clusters (SSCs) seen in both the optical and near-infrared Hubble Space Telescope images of the local ultraluminous starburst galaxy Arp 220. Three of the SSCs are located in the central 0.5-kpc region. The remaining three are in the circumnuclear region between 0.5 and 2.5kpc from the…
Exploration of the BaSeL stellar library for 9 F-type stars COROT potential targets. Comparisons of fundamental stellar parameter determinations
Cuisinier, F.; Lignières, F.; Buser, R. +4 more
The Basel Stellar Library (BaSeL models) is constituted of the merging of various synthetic stellar spectra libraries, with the purpose of giving the most comprehensive coverage of stellar parameters. It has been corrected for systematic deviations detected in respect to UBVRIJHKLM photometry at solar metallicity, and can then be considered as the…
LB 8827: A Variable, Magnetic DBA White Dwarf
Fontaine, G.; Bergeron, P.; Wesemael, F. +3 more
We present accurate CCD spectropolarimetry and spectra that show that the hot DB star LB 8827 (PG 0853+164) is a weakly magnetic, variable DBA white dwarf. We confirm Putney's detection of circular dichroism in the He I lines, but on three occasions we measure a weaker field strength and opposite sign of circular polarization, Be<~10…