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Two New Low Galactic D/H Measurements from the Far Ultraviolet Spectroscopic Explorer
Blair, William P.; Wood, Brian E.; Linsky, Jeffrey L. +3 more
We analyze interstellar absorption observed toward two subdwarf O stars, JL 9 and LS 1274, using spectra taken by the Far Ultraviolet Spectroscopic Explorer (FUSE). Column densities are measured for many atomic and molecular species (H I, D I, C I, N I, O I, P II, Ar I, Fe II, and H2), but our main focus is on measuring the D/H ratios f…
Ring-Diagram Analysis of the Structure of Solar Active Regions
Basu, Sarbani; Antia, H. M.; Bogart, Richard S.
We measure differences in structure between active and quiet regions of the Sun using the frequencies of high-degree modes determined from ring-diagram analyses. We find that both the speed of sound and the adiabatic index Γ1 differ in active regions as compared with quiet regions. In the immediate subsurface layers, the sound speed is …
Discovery of the galaxy counterpart of HDF 850.1, the brightest submillimetre source in the Hubble Deep Field
Muxlow, T. W. B.; Smail, I.; Smith, G. P. +14 more
Despite extensive observational efforts, a convincing optical/infrared identification of the brightest submm source in the Hubble Deep Field, HDF 850.1, has remained elusive after almost four years. This failure is all the more notable given the availability of supporting multifrequency data of unparalleled depth, and subarcsec positional accuracy…
The initial helium abundance of the Galactic globular cluster system
Salaris, M.; Riello, M.; Piotto, G. +1 more
In this paper we estimate the initial He content in about 30% of the Galactic globular clusters (GGCs) from new star counts we have performed on the recently published HST snapshot database of Colour Magnitude Diagrams (Piotto et al. \cite{Piotto02}). More specifically, we use the so-called R-parameter and estimate the He content from a theoretica…
Three Lyα Emitters at z ~ 6: Early GMOS/Gemini Data from the GLARE Project
Bunker, Andrew J.; Glazebrook, Karl; McCarthy, Patrick J. +14 more
We report spectroscopic detection of three z~6 Lyα-emitting galaxies, in the vicinity of the Hubble Ultra Deep Field, from the early data of the Gemini Lyman Alpha at Reionisation Era (GLARE) project. Two objects, GLARE 3001 (z=5.79) and GLARE 3011 (z=5.94), are new detections and are fainter in z' (z'AB=26.37 and …
The Far-Infrared Spectrum of Arp 220
Cernicharo, José; Smith, Howard A.; González-Alfonso, Eduardo +1 more
Infrared Space Observatory Long Wavelength Spectrometer grating observations of the ultraluminous infrared galaxy Arp 220 shows absorption in molecular lines of OH, H2O, CH, NH, and NH3, as well as in the [O I] 63 µm line and emission in the [C II] 158 µm line. We have modeled the continuum and the emission/absorp…
An interplanetary shock traced by planetary auroral storms from the Sun to Saturn
Vourlidas, Angelos; Hansen, Kenneth C.; Prangé, Renée +4 more
A relationship between solar activity and aurorae on Earth was postulated long before space probes directly detected plasma propagating outwards from the Sun. Violent solar eruption events trigger interplanetary shocks that compress Earth's magnetosphere, leading to increased energetic particle precipitation into the ionosphere and subsequent auro…
Chandra and XMM-Newton Observations of the Nucleus of Centaurus A
Hardcastle, M. J.; Worrall, D. M.; Forman, W. R. +4 more
We present X-ray spectra of the nucleus of the nearby radio galaxy Centaurus A from observations with the XMM-Newton EPIC CCD cameras (two exposures separated by 12 months) and the Chandra HETGS. For the first time in an FR I type galaxy, we resolve fluorescent Kα emission from cold, neutral, or near-neutral iron at 6.4 keV, with an rms line width…
The Fundamental Plane of Field Early-Type Galaxies at z = 1
Rix, H. -W.; van der Wel, A.; Franx, M. +1 more
We present deep VLT spectra of early-type galaxies at z~1 in the Chandra Deep Field-South, from which we derive velocity dispersions. Together with structural parameters from Hubble Space Telescope imaging, we can study the fundamental plane for field early-type galaxies at that epoch. We determine accurate mass-to-light ratios (M/L) and colors fo…
Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831
Piskunov, N.; Kochukhov, O.; Drake, N. A. +1 more
We investigate magnetic field geometry and surface distribution of chemical elements in the rapidly oscillating Ap star HR 3831. Results of the model atmosphere analysis of the spectra of this star are combined with the Hipparcos parallax and evolutionary models to obtain new accurate estimates of the fundamental stellar parameters: Teff