Search Publications
Discovery of an 86 AU Radius Debris Ring around HD 181327
Henning, Thomas; Schneider, Glenn; Hines, Dean C. +11 more
HST NICMOS PSF-subtracted coronagraphic observations of HD 181327 have revealed the presence of a ringlike disk of circumstellar debris seen in 1.1 µm light scattered by the disk grains, surrounded by a diffuse outer region of lower surface brightness. The annular disk appears to be inclined by 31.7d+/-1.6d from face-on, with the disk major-…
The Arches Cluster Mass Function
Najarro, F.; Figer, Donald F.; Kim, Sungsoo S. +1 more
We have analyzed H- and Ks-band images of the Arches cluster obtained using the NIRC2 instrument on Keck with the laser guide star adaptive optics (LGS AO) system. With the help of the LGS AO system, we were able to obtain the deepest ever photometry for this cluster and its neighborhood and derive the background-subtracted present-day …
A Survey of Galaxy Kinematics to z~1 in the TKRS/GOODS-N Field. II. Evolution in the Tully-Fisher Relation
Weiner, Benjamin J.; Faber, S. M.; Willmer, Christopher N. A. +7 more
We use kinematic measurements of a large sample of galaxies from the Team Keck Redshift Survey in the GOODS-N field to measure evolution in the optical and near-IR Tully-Fisher (TF) relations to z=1.2. We construct TF relations with integrated line-of-sight velocity widths of ~1000 galaxies in B and ~670 in J; these relations have large scatter, a…
Solar Sources of Impulsive Solar Energetic Particle Events and Their Magnetic Field Connection to the Earth
Liu, Yang; Yashiro, Seiji; Nitta, Nariaki V. +3 more
This paper investigates the solar origin of impulsive solar energetic particle (SEP) events, often referred to as 3He-rich flares, by attempting to locate the source regions of 117 events as observed at ~2-3 MeV amu-1. Given large uncertainties as to when ions at these energies were injected, we use type III radio bursts that…
Identification of the OGLE-2003-BLG-235/MOA-2003-BLG-53 Planetary Host Star
Anderson, Jay; Udalski, Andrzej; Gould, Andrew +2 more
We present the results of HST observations of the host star for the first definitive extrasolar planet detected by microlensing. The light-curve model for this event predicts that the lens star should be separated from the source star by ~6 mas at the time of the HST images. If the lens star is a late G, K, or early M dwarf, then it will be visibl…
The Enceladus and OH Tori at Saturn
Tokar, R. L.; Johnson, R. E.; Sittler, E. C. +4 more
The remarkable observation that Enceladus, a small icy satellite of Saturn, is actively venting has led to the suggestion that ejected water molecules are the source of the toroidal atmosphere observed at Saturn for over a decade using the Hubble Space Telescope (HST). Here we show that the venting leads directly to a new feature, a narrow Encelad…
New Chandra Observations of the Jet in 3C 273. I. Softer X-Ray than Radio Spectra and the X-Ray Emission Mechanism
Meisenheimer, Klaus; Jester, Sebastian; Harris, D. E. +1 more
The jet in 3C 273 is a high-power quasar jet with radio, optical, and X-ray emission, whose size and brightness allow a detailed study of the emission processes acting in it. We present deep Chandra observations of this jet and analyze the spectral properties of the jet emission from radio through X-rays. We find that the X-ray spectra are signifi…
The Mass of the Central Black Hole in the Seyfert Galaxy NGC 4151
Peterson, Bradley M.; Onken, Christopher A.; Metzroth, Kyle G.
In order to improve the reverberation-mapping-based estimate of the mass of the central supermassive black hole in the Seyfert 1 galaxy NGC 4151, we have reanalyzed archival ultraviolet monitoring spectra from two campaigns undertaken with the International Ultraviolet Explorer. We measure emission-line time delays for four lines, C IV λ1549, He I…
The Physical and Photometric Properties of High-Redshift Galaxies in Cosmological Hydrodynamic Simulations
Papovich, C.; Davé, R.; Finlator, K. +1 more
We study the physical and photometric properties of galaxies at z=4 in cosmological hydrodynamic simulations of a ΛCDM universe. We focus on galaxies satisfying the ``B dropout'' criteria of the Great Observatories Origins DEEP Survey (GOODS). Our simulations predict that high-redshift galaxies show strong correlations in star formation rate (SFR)…
The Pure Noncollisional Blue Straggler Population in the Giant Stellar System ω Centauri
Pancino, E.; Bellazzini, M.; Origlia, L. +3 more
We have used high spatial resolution data from the Hubble Space Telescope (HST) and wide-field ground-based observations to search for blue straggler stars (BSSs) over the entire radial extent of the large stellar system ω Centauri. We have detected the largest population of BSSs ever observed in any stellar system. Even though the sample is restr…