Search Publications
The Chemical Composition Contrast between M3 and M13 Revisited: New Abundances for 28 Giant Stars in M3
Guhathakurta, Puragra; Sneden, Christopher; Peterson, Ruth C. +2 more
We report new chemical abundances of 23 bright red giant members of the globular cluster M3, based on high-resolution (R~45,000) spectra obtained with the Keck I telescope. The observations, which involve the use of multislits in the HIRES Keck I spectrograph, are described in detail. Combining these data with a previously reported small sample of…
Comparing the properties of local globular cluster systems: implications for the formation of the Galactic halo
Mackey, A. D.; Gilmore, G. F.
We investigate the hypothesis that some fraction of the globular clusters presently observed in the Galactic halo formed in external dwarf galaxies. This is done by means of a detailed comparison between the `old halo', `young halo' and `bulge/disc' subsystems defined by Zinn and the globular clusters in the Large Magellanic Cloud, Small Magellani…
Solar Wind-Induced Atmospheric Erosion at Mars: First Results from ASPERA-3 on Mars Express
Kallio, E.; Fedorov, A.; Budnik, E. +42 more
The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the mart…
A Survey of Extended Radio Jets with Chandra and the Hubble Space Telescope
Maraschi, L.; Cheung, C. C.; Tavecchio, F. +5 more
We present the results from an X-ray and optical survey of a sample of 17 radio jets in active galactic nuclei performed with Chandra and the Hubble Space Telescope. The sample was selected from the radio and is unbiased toward detection at shorter wavelengths, but preferentially it includes beamed sources. We find that X-ray emission is common on…
The XMM-LSS survey. Survey design and first results
Refregier, Alexandre; Gandhi, Poshak; Mellier, Yannick +36 more
The XMM Large Scale Structure survey (XMM-LSS) is a medium deep large area X-ray survey. Its goal is to extend large scale structure investigations attempted using ROSAT cluster samples to two redshift bins between 0<z<1 while maintaining the precision of earlier studies. Two main goals have constrained the survey design: the evolutionary st…
The Host Galaxy of GRB 031203: Implications of Its Low Metallicity, Low Redshift, and Starburst Nature
Chen, Hsiao-Wen; Graham, James R.; Dressler, Alan +6 more
We present Keck/NIRSPEC near-IR images and Magellan/IMACS optical spectroscopy of the host galaxy of GRB 031203. The host is an actively star-forming galaxy at z=0.1055+/-0.0001. This is the lowest redshift GRB to date, aside from GRB 980425. From the hydrogen Balmer lines, we infer an extinction of AV=3.62+/-0.25 or a total reddening E…
The sub-energetic γ-ray burst GRB 031203 as a cosmic analogue to the nearby GRB 980425
Cenko, S. B.; Berger, E.; Frail, D. A. +13 more
Over the six years since the discovery of the γ-ray burst GRB 980425, which was associated with the nearby (distance ~40Mpc) supernova 1998bw, astronomers have debated fiercely the nature of this event. Relative to bursts located at cosmological distance (redshift z ~ 1), GRB 980425 was under-luminous in γ-rays by three orders of magnitude. Radio …
Extremely high speed solar wind: 29-30 October 2003
McComas, D. J.; Steinberg, J. T.; Burlaga, L. F. +5 more
On 29-30 October 2003 the Solar Wind Electron Proton Alpha Monitor (SWEPAM) instrument on the Advanced Composition Explorer (ACE) spacecraft measured solar wind speeds in excess of 1850 km/s, some of the highest speeds ever directly measured in the solar wind. These speeds were observed following two large coronal mass ejection (CME) driven shocks…
The Far-Ultraviolet Spectra of TW Hydrae. II. Models of H2 Fluorescence in a Disk
Herczeg, Gregory J.; Valenti, Jeff A.; Johns-Krull, Christopher M. +2 more
We measure the temperature of warm gas at planet-forming radii in the disk around the classical T Tauri star (CTTS) TW Hya by modeling the H2 fluorescence observed in Hubble Space Telescope Space Telescope Imaging Spectrograph and Far Ultraviolet Spectroscopic Explorer spectra. Strong Lyα emission irradiates a warm disk surface within 2…
Near-Infrared Bright Galaxies at z~=2. Entering the Spheroid Formation Epoch?
Cimatti, A.; Daddi, E.; Tozzi, P. +11 more
Spectroscopic redshifts have been measured for nine K-band luminous galaxies at 1.7<z<2.3, selected with Ks<20 in the K20 survey region of the Great Observatories Origins Deep Survey (GOODS) area. Star formation rates (SFRs) of ~100-500 Msolar yr-1 are derived when dust extinction is taken into account. Th…