Search Publications
The Evolution of Early-Type Galaxies in Distant Clusters. III. M/LV Ratios in the z=0.33 Cluster CL 1358+62
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +1 more
Internal kinematics, length scales, and surface brightnesses have been determined for a large sample of 53 galaxies in the cluster Cl 1358+62 at z=0.33 from Keck spectroscopy and Hubble Space Telescope WFPC2 imaging over a 1.5 h-1x1.5 h-1 Mpc2 field of view. These data have been used to constrain the evolution of e…
Detection and Photometry of Hot Horizontal Branch Stars in the Core of M32
Ferguson, Henry C.; Brown, Thomas M.; Kimble, Randy A. +2 more
We present the deepest near-UV image of M32 to date, which for the first time resolves hot horizontal branch (HB) stars in an elliptical galaxy. Given the near-solar metallicity of M32, much larger than that of globular clusters, the existence of an extended horizontal branch is a striking example of the second parameter effect, and, most importan…
Tests of the Accelerating Universe with Near-Infrared Observations of a High-Redshift Type IA Supernova
Spyromilio, J.; Filippenko, Alexei V.; Leibundgut, B. +25 more
We have measured the rest-frame B-, V-, and I-band light curves of a high-redshift type Ia supernova (SN Ia), SN 1999Q (z=0.46), using the Hubble Space Telescope (HST) and ground-based near-infrared detectors. A goal of this study is the measurement of the color excess, EB-I, a sensitive indicator of interstellar or intergalactic dust, …
X-Ray Sources in the Hubble Deep Field Detected by Chandra
Hornschemeier, A. E.; Brandt, W. N.; Sargent, W. L. W. +11 more
We present first results from an X-ray study of the Hubble Deep Field North (HDF-N) and its environs obtained using 166 ks of data collected by the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. This is the deepest X-ray observation ever reported, and in the HDF-N itself we detect six X-ray sources down to a 0.5-8…
High-Resolution Imaging of Molecular Gas and Dust in the Antennae (NGC 4038/39): Super Giant Molecular Complexes
Wilson, Christine D.; Madden, Suzanne C.; Charmandaris, Vassilis +1 more
We present new aperture synthesis CO maps of the Antennae (NGC 4038/39) obtained with the Caltech Millimeter Array. These sensitive images show molecular emission associated with the two nuclei and a partial ring of star formation to the west of NGC 4038, as well as revealing the large extent of the extranuclear region of star formation (the ``ove…
Implications of Solar Wind Composition for Cometary X-Rays
Schwadron, N. A.; Cravens, T. E.
Solar wind composition provides a strong source of variability for cometary X-rays. Using recently constrained composition observations from the Solar Wind Ion Composition Spectrometer on the Ulysses spacecraft (SWICS/Ulysses) and information on ion-neutral charge-transfer collisions, we model cometary X-ray emission and its variability. Fast and …
STIS Observations of HE II Gunn-Peterson Absorption toward Q0302-003
Tripp, Todd M.; Jenkins, Edward B.; Hubeny, Ivan +5 more
The ultraviolet spectrum (1145-1720 Å) of the distant quasar Q0302-003 (z=3.286) was observed at 1.8 Å resolution with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. A total integration time of 23,280 s was obtained. The spectrum clearly delineates the Gunn-Peterson He II absorption trough, produced by He II Lyα along …
The Local Lyα Forest. II. Distribution of H I Absorbers,Doppler Widths, and Baryon Content
Shull, J. Michael; Stocke, John T.; Penton, Steven V.
In Paper I of this series we described observations of 15 extragalactic targets taken with the Hubble Space Telescope+GHRS+G160M grating for studies of the low-z Lyα forest. We reported the detection of 111 Lyα absorbers at significance level (SL) >=3 σ, 81 with SL>=4 σ, in the redshift range 0.002<z<0.069, over a total path length cΔz…
The Origin of Runaway Stars
de Bruijne, J. H. J.; de Zeeuw, P. T.; Hoogerwerf, R.
Milliarcsecond astrometry provided by Hipparcos and by radio observations makes it possible to retrace the orbits of some of the nearest runaway stars and pulsars to determine their site of origin. The orbits of the runaways AE Aurigae and µ Columbae and of the eccentric binary ι Orionis intersected each other ~2.5 Myr ago in the nascent Tra…
An IUE Atlas of Pre-Main-Sequence Stars. II. Far-Ultraviolet Accretion Diagnostics in T Tauri Stars
Valenti, Jeff A.; Johns-Krull, Christopher M.; Linsky, Jeffrey L.
We use our ultraviolet (UV) atlas of pre-main-sequence stars constructed from all useful, short-wavelength, low-resolution spectra in the International Ultraviolet Explorer (IUE) satellite Final Archive to analyze the short-wavelength UV properties of 49 T Tauri stars (TTSs). We compare the line and continuum fluxes in these TTSs with each other a…