Search Publications
Hydrogen Column Density Evaluations toward Capella: Consequences on the Interstellar Deuterium Abundance
Ferlet, R.; Vidal-Madjar, A.
The deuterium abundance evaluation in the direction of Capella has for a long time been used as a reference for the local interstellar medium (ISM) within our Galaxy. We show here that broad and weak H I components could be present on the Capella line of sight, leading to a large new additional systematic uncertainty on the N(H I) evaluation. We f…
Identifying Gamma-Ray Burst Remnants through Positron Annihilation Radiation
Loeb, Abraham; Furlanetto, Steven R.
We model the annihilation of relic positrons produced in a gamma-ray burst (GRB) after its afterglow has faded. We find that the annihilation signal from at least one GRB remnant in the Milky Way should be observable with future space missions such as the International Gamma-Ray Astrophysical Laboratory and the Energetic X-ray Imaging Survey Teles…
Westphal-MMD 11: An Interacting, Submillimeter Luminous Lyman Break Galaxy
Chapman, S. C.; Shapley, A.; Windhorst, R. +1 more
We present new Hubble Space Telescope, high-resolution optical imaging of the submillimeter luminous Lyman break galaxy (LBG), Westphal-MMD 11, an interacting starburst at z=2.979. The new imaging data, in conjunction with reanalysis of Keck optical and near-IR spectra, demonstrate MMD 11 to be an interacting system of at least three components: a…
Effects of Temperature Bias on Nanoflare Statistics
Aschwanden, Markus J.; Charbonneau, Paul
Statistics of solar flares, microflares, and nanoflares have been gathered over an energy range of some 8 orders of magnitude, over E~1024-1032 ergs. Frequency distributions of flare energies are always determined in a limited temperature range, e.g., at T~1-2 MK if the 171 and 195 Å filters are used from an extreme ultraviol…
Kinematics of the HH 111 Jet from the Space Telescope Imaging Spectrograph
Garnavich, P. M.; Raga, A. C.; Noriega-Crespo, A. +4 more
We present a long-slit spectrum of the Herbig-Haro object HH 111, obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. This spectrum has a spectral resolution of ~50 km s-1, so it gives a good picture of the kinematical properties of the observed object at very high angular resolution. We find that…
Associated Absorption Lines in the Radio-loud Quasar 3C 351: Far-Ultraviolet Echelle Spectroscopy from the Hubble Space Telescope
Kriss, G. A.; Green, R. F.; Kaiser, M. E. +3 more
As one of the most luminous radio-loud quasars showing intrinsic ultraviolet (UV) and X-ray absorption, 3C 351 provides a laboratory for studying the kinematics and physical conditions of such ionized absorbers. We present an analysis of the intrinsic absorption lines in the high-resolution (~7 km s-1) far-UV spectrum that was obtained …
High-Resolution Spectroscopy of G191-B2B in the Extreme-Ultraviolet
Culhane, J. L.; Barstow, M. A.; Brown, C. M. +14 more
We report a high-resolution (R=3000-4000) spectroscopic observation of the DA white dwarf G191-B2B in the extreme-ultraviolet band 220-245 Å. A low-density, ionized He component is clearly present along the line of sight, which if completely interstellar implies a He ionization fraction considerably higher than is typical of the local interstellar…
The Massive Stellar Content in the Starburst NGC 3049: A Test for Hot-Star Models
Heckman, Timothy M.; Leitherer, Claus; González Delgado, Rosa M. +1 more
The objective of this work is twofold. First, we seek evidence for or against the depletion of massive stars in metal-rich starbursts. A second, equally important goal is to perform a consistency test of the latest generation of starburst models in such a high-metallicity environment. We have obtained high spatial resolution ultraviolet and optica…
Detection of Optical Synchrotron Emission from the Radio Jet of 3C 279
Cheung, C. C.
We report the detection of optical and ultraviolet emission from the kiloparsec-scale jet of the well-known quasar 3C 279. A bright knot, discovered in archival V- and U-band Hubble Space Telescope Faint Object Camera images, is coincident with a peak in the radio jet ~0.6" from the nucleus. The detection was also confirmed in Wide Field Planetary…
The Cepheid Period-Luminosity Relation and the Maser Distance to NGC 4258
Marconi, M.; Musella, I.; Caputo, F.
In a recent paper describing Hubble Space Telescope observations of Cepheids in the spiral galaxy NGC 4258, Newman et al. report that the revised calibrations and methods for the Key Project on the Extragalactic Distance Scale yield that the true distance modulus of this galaxy is µ0,4258=29.40+/-0.09 mag, corresponding to a metri…