Search Publications
Comparison of the Sacramento Peak Fe XIV Index with a Model Index Computed from Differential Emission Measure Maps
Newmark, J. S.; Cook, J. W.; Altrock, R. C.
We compare the Sacramento Peak Fe XIV 5303 Å green line index with a model index time series for the period of operations of the EUV Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO), covering the years 1996-2002, from cycle minimum past the peak of the current activity cycle 23. We compute a differential emission meas…
H1517+656: The Birth of a BL Lacertae Object?
Urry, C. Megan; O'Dowd, Matthew; Scarpa, Riccardo +2 more
H1517+656 is an unusual source, even for a BL Lac object. It is one of the most luminous BL Lac objects known, with extreme emission properties at radio, optical, and X-ray frequencies. Furthermore, in our WFPC2 snapshot survey we discovered a series of peculiar arcs describing a 2.4" radius ring surrounding the source. This paper describes follow…
Type Ia Supernova Discoveries at z > 1 from the Hubble Space Telescope: Evidence for Past Deceleration and Constraints on Dark Energy Evolution
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +16 more
We have discovered 16 Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to provide the first conclusive evidence for cosmic deceleration that preceded the current epoch of cosmic acceleration. These objects, discovered during the course of the GOODS ACS Treasury program, include 6 of the 7 highest redshift SNe Ia…
The Great Observatories Origins Deep Survey: Initial Results from Optical and Near-Infrared Imaging
Cesarsky, C.; Wolf, C.; Jogee, S. +54 more
This special issue of the Astrophysical Journal Letters is dedicated to presenting initial results from the Great Observatories Origins Deep Survey (GOODS) that are primarily, but not exclusively, based on multiband imaging data obtained with the Hubble Space Telescope and the Advanced Camera for Surveys (ACS). The survey covers roughly 320 arcmin…
A Large Stellar Evolution Database for Population Synthesis Studies. I. Scaled Solar Models and Isochrones
Salaris, Maurizio; Cassisi, Santi; Pietrinferni, Adriano +1 more
We present a large and updated stellar evolution database for low-, intermediate-, and high-mass stars in a wide metallicity range, suitable for studying Galactic and extragalactic simple and composite stellar populations using population synthesis techniques. The stellar mass range is between ~0.5 and 10 Msolar with a fine mass spacing…
A New Photometric Technique for the Joint Selection of Star-forming and Passive Galaxies at 1.4 <~ z <~ 2.5
Cimatti, A.; Daddi, E.; Tozzi, P. +5 more
A simple two-color selection based on B-, z-, and K-band photometry is proposed for culling galaxies at 1.4<~z<~2.5 in K-selected samples and classifying them as star-forming or passive systems. The method is calibrated on the highly complete spectroscopic redshift database of the K20 survey, verified with simulations and tested on other dat…
Detection of Oxygen and Carbon in the Hydrodynamically Escaping Atmosphere of the Extrasolar Planet HD 209458b
Ehrenreich, D.; Lecavelier des Etangs, A.; Ferlet, R. +7 more
Four transits of the planet orbiting the star HD 209458 were observed with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. The wavelength domain (1180-1710 Å) includes H I as well as C I, C II, C IV, N V, O I, S I, Si II, Si III, and Si IV lines. During the transits, absorptions are detected in H I, O I, and C II (5%+…
ω Centauri: The Population Puzzle Goes Deeper
Anderson, Jay; Bedin, Luigi R.; Piotto, Giampaolo +4 more
We present Hubble Space Telescope observations that show a bifurcation of colors in the middle main sequence of the globular cluster ω Centauri. We see this in three different fields, observed with different cameras and filters. We also present high-precision photometry of a central Advanced Camera for Surveys field, which shows a number of main-s…
Twenty-Three High-Redshift Supernovae from the Institute for Astronomy Deep Survey: Doubling the Supernova Sample at z > 0.7
Filippenko, Alexei V.; Wainscoat, Richard J.; Garnavich, Peter +29 more
We present photometric and spectroscopic observations of 23 high-redshift supernovae (SNe) spanning a range of z=0.34-1.03, nine of which are unambiguously classified as Type Ia. These SNe were discovered during the IfA Deep Survey, which began in 2001 September and observed a total of 2.5 deg2 to a depth of approximately m~25-26 in RIZ…
The Absence of Crystalline Silicates in the Diffuse Interstellar Medium
Tielens, A. G. G. M.; Kemper, F.; Vriend, W. J.
Infrared spectroscopy provides a direct handle on the composition and structure of interstellar dust. We have studied the dust along the line of sight toward the Galactic center using Short Wavelength Spectrometer data obtained with the Infrared Space Observatory (ISO). We focused on the wavelength region from 8 to 13 µm, which is dominated …