Search Publications
Ices in the Edge-on Disk CRBR 2422.8-3423: Spitzer Spectroscopy and Monte Carlo Radiative Transfer Modeling
van Dishoeck, Ewine F.; Dullemond, Cornelis P.; Pontoppidan, Klaus M. +5 more
We present 5.2-37.2 µm spectroscopy of the edge-on circumstellar disk CRBR 2422.8-3423 obtained using the Infrared Spectrograph (IRS) of the Spitzer Space Telescope. The IRS spectrum is combined with ground-based 3-5 µm spectroscopy to obtain a complete inventory of solid-state material present along the line of sight toward the source…
First Results from the CHARA Array. I. An Interferometric and Spectroscopic Study of the Fast Rotator α Leonis (Regulus)
Gies, D. R.; Berger, D. H.; McAlister, H. A. +13 more
We report on K-band interferometric observations of the bright, rapidly rotating star Regulus (type B7 V) made with the CHARA Array on Mount Wilson, California. Through a combination of interferometric and spectroscopic measurements, we have determined for Regulus the equatorial and polar diameters and temperatures, the rotational velocity and per…
The Evolution and Structure of Early-Type Field Galaxies: A Combined Statistical Analysis of Gravitational Lenses
Kochanek, C. S.; Rusin, D.
We introduce a framework for simultaneously investigating the structure and luminosity evolution of early-type gravitational lens galaxies. The method is based on the fundamental plane, which we interpret using the aperture mass-radius relations derived from lensed image geometries. We apply this method to our previous sample of 22 lens galaxies w…
Can the Steep Mass Profile of A1689 Be Explained by a Triaxial Dark Halo?
Broadhurst, Tom; Oguri, Masamune; Umetsu, Keiichi +1 more
The steep mass profile of A1689 derived from recent detailed lensing observations is not readily reconciled with the low-concentration halos predicted by the standard cold dark matter (CDM) model. However, halo triaxiality may act to bias the profile constraints derived assuming a spherically symmetric mass distribution, since lensing relates only…
Hubble Space Telescope Observations of Element Abundances in Low-Redshift Damped Lyα Galaxies and Implications for the Global Metallicity-Redshift Relation
York, Donald G.; Fall, S. Michael; Kulkarni, Varsha P. +4 more
Most models of cosmic chemical evolution predict that the mass-weighted mean interstellar metallicity of galaxies should rise with time from a low value ~1/30 solar at z~3 to a nearly solar value at z=0. In the absence of any selection effects, the damped Lyα absorbers (DLAs) in quasar spectra are expected to show such a rise in global metallicity…
The Low-z Intergalactic Medium. I. O VI Baryon Census
Shull, J. Michael; Danforth, Charles W.
Intergalactic absorbers along lines of sight to distant quasars are a powerful diagnostic for the evolution and content of the intergalactic medium (IGM). In this study, we use the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite to search 129 known Lyα absorption systems at z<0.15 toward 31 active galactic nuclei (AGNs) for correspondin…
Coronal Evolution of the Sun in Time: High-Resolution X-Ray Spectroscopy of Solar Analogs with Different Ages
Skinner, Stephen L.; Güdel, Manuel; Ness, Jan-Uwe +3 more
We investigate the long-term evolution of X-ray coronae of solar analogs based on high-resolution X-ray spectroscopy and photometry with XMM-Newton. Six nearby main-sequence G stars with ages between ~0.1 and ~1.6 Gyr and rotation periods between ~1 and 12.4 days have been observed. We use the X-ray spectra to derive coronal element abundances of …
Evolution of the Near-Infrared Tully-Fisher Relation: Constraints on the Relationship between the Stellar and Total Masses of Disk Galaxies since z~1
Conselice, Christopher J.; Ellis, Richard S.; Bundy, Kevin +3 more
Using a combination of Keck spectroscopy and near-infrared imaging, we investigate the K-band and stellar-mass Tully-Fisher relation for 101 disk galaxies at 0.2<z<1.2, with the goal of placing the first observational constraints on the assembly history of halo and stellar mass. Our main result is a lack of evolution in either the K-band or …
From Radio to X-Ray: Flares on the dMe Flare Star EV Lacertae
Hawley, Suzanne L.; Johns-Krull, Christopher M.; Osten, Rachel A. +2 more
We present the results of a campaign to observe flares on the M dwarf flare star EV Lacertae over the course of two days in 2001 September, utilizing a combination of radio continuum, optical photometric and spectroscopic, ultraviolet spectroscopic, and X-ray spectroscopic observations to characterize the multiwavelength nature of flares from this…
The Low End of the Supermassive Black Hole Mass Function: Constraining the Mass of a Nuclear Black Hole in NGC 205 via Stellar Kinematics
Joseph, Charles L.; Ferrarese, Laura; Merritt, David +1 more
Hubble Space Telescope (HST) images and spectra of the nucleated dwarf elliptical galaxy NGC 205 are combined with three-integral axisymmetric dynamical models to constrain the mass MBH of a putative nuclear black hole. This is only the second attempt, after M33, to use resolved stellar kinematics to search for a nuclear black hole with…