Search Publications
Star Formation and X-Ray Emission in Distant Star-Forming Galaxies
Cohen, Judith G.
About 45% of the point sources detected in the 2 Ms Chandra exposure of the Hubble Deep Field-North (HDF-N) can be matched with moderately bright galaxies with z<1.4 that have been studied by the Caltech Faint Galaxy Redshift Survey. Although the optical spectra of these galaxies appear normal, based on their X-ray properties ~20% of them appea…
Atomic Data and Emission-Line Intensities for Ca VII
Bhatia, A. K.; Landi, E.
In the present work we calculate energy levels, transition probabilities, and electron-ion collisional excitation rates for the 3s23p2, 3s3p3, and 3s23p3d configurations of the silicon-like ion Ca VII. The total number of intermediate coupling levels considered is 27. Collision strengths are calculated a…
Preferential Heating of Particles by H-Cyclotron Waves Generated by a Global Magnetohydrodynamic Mode in Solar Coronal Holes
Zhang, T. X.
Preferential heating of particles by H-cyclotron waves is investigated to explain the recent measurements of anisotropic heating of ions in solar coronal holes. First, the dispersion relation of H-cyclotron waves generated by a global MHD mode in the solar coronal hole is numerically studied. Then, heating of H, O+5, and Mg+9…
On the Origin of the High-Ionization Intermediate-Velocity Gas toward HD 14434
Sembach, Kenneth R.; Meyer, David M.; Lauroesch, James T. +2 more
We present Far-Ultraviolet Spectroscopic Explorer and Space Telescope Imaging Spectrograph observations of high-ionization interstellar absorption toward HD 14434 (l=135.1d, b=-3.8d d~2.3 kpc), an O5.5 V star in the Perseus OB1 association. Intermediate-velocity interstellar Si IV and C IV absorption is present at VLSR=-67 km s-1
Lens or Binary? Chandra Observations of the Wide-Separation Broad Absorption Line Quasar Pair UM 425
Green, Paul J.; Aldcroft, Thomas L.
We have obtained a 110 ks Chandra ACIS-S exposure of UM 425, a pair of QSOs at z=1.47 separated by 6.5", which show remarkably similar emission and broad absorption line (BAL) profiles in the optical/UV. Our 5000 count X-ray spectrum of UM 425A (the brighter component) is well fitted with a power law (photon spectral index Γ=2.0) partially covered…
Hubble Space Telescope Observations of Ultraviolet Oscillations in WZ Sagittae During the Decline from Outburst
Szkody, Paula; Sion, Edward M.; Godon, Patrick +4 more
We present a time series analysis of Hubble Space Telescope observations of WZ Sge obtained in 2001 September, October, November, and December as WZ Sge declined from its 2001 July superoutburst. Previous analysis of these data showed the temperature of the white dwarf decreased from ~29,000 to ~18,000 K. In this study we binned the spectra over w…
Early-Type Stars: Most Favorable Targets for Astrometrically Detectable Planets in the Habitable Zone
Fischer, Debra A.; Gould, Andrew; Ford, Eric B.
Early-type stars appear to be a difficult place to look for planets astrometrically. First, they are relatively heavy, and for fixed planetary mass the astrometric signal falls inversely as the stellar mass. Second, they are relatively rare (and so tend to be more distant), and for fixed orbital separation the astrometric signal falls inversely as…
Hot Dust in Radio-loud Active Galactic Nuclei
Haas, Martin; Siebenmorgen, Ralf; Freudling, Wolfram
We have measured mid-infrared (MIR) fluxes of 3C sources on images taken with ISOCAM on board the Infrared Space Observatory (ISO). The photometric data were combined with existing photometry at other wavelengths to assemble the spectral energy distribution (SED) for each galaxy from infrared to radio wavelengths. In addition, we used ISOPHOT spec…
ERO R1 in the Field of CL 0939+4713: Evidence for an S0-like Galaxy at z ~ 1.5
Kobayashi, Naoto; Terada, Hiroshi; Imanishi, Masatoshi +11 more
We present further observations of the extremely red object ERO J094258+4659.2, identified earlier by Iye et al. as ERO R1 in their deep images of the cluster A851. We estimate its redshift independently by eight-band photometric redshift determination and cross-correlation of a new H-band spectrum with the optical spectra of local E/S0 galaxies a…
New Identifications of Mn VII and Fe VIII Lines Belonging to Transitions of the Type 3p64p-3p64d and 3p53d2-3p64d
Feldman, U.; Ekberg, J. O.
The Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer aboard the Solar and Heliospheric Observatory (SOHO) recorded a large number of spectra in the 500-1600 Å region. Many of the detected spectral lines have been identified as transitions in ions from elements with low-to-moderate atomic numbers (Z<=20). However, a subst…