Search Publications
Ultraviolet Survey of CO and H2 in Diffuse Molecular Clouds: The Reflection of Two Photochemistry Regimes in Abundance Relationships
Abel, N. P.; Gredel, R.; Lambert, D. L. +4 more
We carried out a comprehensive far-UV survey of 12CO and H2 column densities along diffuse molecular Galactic sight lines. This sample includes new measurements of CO from HST spectra along 62 sight lines and new measurements of H2 from FUSE data along 58 sight lines. In addition, high-resolution optical data were …
The broad-lined Type Ic supernova 2003jd
Pian, E.; Frontera, F.; Gal-Yam, A. +28 more
The results of a worldwide coordinated observational campaign on the broad-lined Type Ic supernova (SN Ic) 2003jd are presented. In total, 74 photometric data points and 26 spectra were collected using 11 different telescopes. SN 2003jd is one of the most luminous SN Ic ever observed. A comparison with other Type Ic supernovae (SNe Ic) confirms th…
The identification of liquid ethane in Titan's Ontario Lacus
Sotin, C.; Barnes, J. W.; Brown, R. H. +7 more
Titan was once thought to have global oceans of light hydrocarbons on its surface, but after 40 close flybys of Titan by the Cassini spacecraft, it has become clear that no such oceans exist. There are, however, features similar to terrestrial lakes and seas, and widespread evidence for fluvial erosion, presumably driven by precipitation of liquid…
Electron temperature anisotropy constraints in the solar wind
Maksimovic, Milan; Marsch, Eckart; Scime, Earl E. +3 more
We have performed a statistical study of a substantial amount of electron data acquired in the solar wind to understand the constraints on electron temperature anisotropy by plasma instabilities and Coulomb collisions. We use a large data set of electron measurements from three different spacecraft (Helios I, Cluster II, and Ulysses) collected in …
Evidence of Cosmic Evolution of the Stellar Initial Mass Function
van Dokkum, Pieter G.
Theoretical arguments and indirect observational evidence suggest that the stellar IMF may evolve with time, such that it is more weighted toward high-mass stars at higher redshift. Here we test this idea by comparing the rate of luminosity evolution of massive early-type galaxies in clusters at 0.02 <= z<= 0.83 to the rate of their color ev…
CoRoT sounds the stars: p-mode parameters of Sun-like oscillations on HD 49933
Auvergne, M.; Baudin, F.; Jiménez-Reyes, S. J. +19 more
Context: The first asteroseismology results from CoRoT are presented, on a star showing Sun-like oscillations. We have analyzed a 60 day lightcurve of high-quality photometric data collected by CoRoT on the F5 V star HD 49933. The data reveal a rich spectrum of overtones of low-degree p modes.
Aims: Our aim was to extract robust estimates of t…
Observation of energetic electrons within magnetic islands
Daly, P. W.; Khotyaintsev, Y.; Vaivads, A. +10 more
Magnetic reconnection is the underlying process that releases impulsively an enormous amount of magnetic energy in solar flares , flares on strongly magnetized neutron stars and substorms in the Earth's magnetosphere. Studies of energy release during solar flares, in particular, indicate that up to 50% of the released energy is carried by accelera…
The Low-z Intergalactic Medium. III. H I and Metal Absorbers at z < 0.4
Shull, J. Michael; Danforth, Charles W.
We conduct an ultraviolet (HST and FUSE) spectroscopic survey of H I (Lyman lines) and seven metal ions (O VI, N V, C IV, C III, Si IV, Si III, Fe III) in the low-redshift IGM at z < 0.4. We analyzed 650 Lyα absorbers over redshift path length Δ z = 5.27, detecting numerous absorbers: 83 O VI systems, 39 C III, 53 Si III, 24 C IV, 24 N V, and s…
Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity
Faucher-Giguère, Claude-André; Hernquist, Lars; Lidz, Adam +1 more
We investigate the implications of the intergalactic opacity for the evolution of the cosmic UV luminosity density and its sources. Our main constraint is our measurement of the Lyα forest opacity at redshifts 2 <= z <= 4.2 from 86 high-resolution quasar spectra. In addition, we impose the requirements that H I must be reionized by z = 6 and…
A model of Titan's aerosols based on measurements made inside the atmosphere
Tomasko, M. G.; Doose, L.; Engel, S. +5 more
The descent imager/spectral radiometer (DISR) instrument aboard the Huygens probe into the atmosphere of Titan measured the brightness of sunlight using a complement of spectrometers, photometers, and cameras that covered the spectral range from 350 to 1600 nm, looked both upward and downward, and made measurements at altitudes from 150 km to the …