Search Publications
Space Velocities of Southern Globular Clusters. VI. Nine Clusters in the Inner Milky Way
Casetti-Dinescu, Dana I.; Girard, Terrence M.; Korchagin, Vladimir I. +2 more
We have measured the absolute proper motions of nine low-latitude, inner Galaxy globular clusters, namely, NGC 6273 (M 19), NGC 6284, NGC 6287, NGC 6293, NGC 6333 (M 9), NGC 6342, NGC 6356, NGC 6388, and NGC 6441. These are the first determinations ever made for these clusters. The proper motions are on the International Celestial Reference System…
A Wide-Field Survey of the Orion Nebula Cluster in the Near-Infrared
Robberto, M.; Scandariato, G.; Da Rio, N. +4 more
We present J, H, and K S photometry of the Orion Nebula Cluster (ONC) obtained at the CTIO/Blanco 4 m telescope at Cerro Tololo with the Infrared Side Port Imager camera. From the observations we have assembled a catalog of about ~7800 sources distributed over an area of approximately 30' × 40', the largest of any survey deeper than th…
The Size, Density, and Formation of the Orcus-Vanth System in the Kuiper Belt
Ragozzine, D.; Brown, M. E.; Stansberry, J. +1 more
The Kuiper Belt object (KBO) Orcus and its satellite Vanth form an unusual system in the Kuiper Belt. While most large KBOs have small satellites in circular orbits and smaller KBOs and their satellites tend to be much closer in size, Orcus sits in between these two regimes. Orcus is among the largest objects known in the Kuiper Belt, but the rela…
The Araucaria Project: First Cepheid Distance to the Sculptor Group Galaxy NGC 7793 from Variables Discovered in a Wide-field Imaging Survey
Udalski, Andrzej; Soszyński, Igor; Wyrzykowski, Łukasz +12 more
For the first time, we have detected Cepheid variables in the Sculptor Group spiral galaxy NGC 7793. From wide-field images obtained in the optical V and I bands on 56 nights in 2003-2005, we have discovered 17 long-period (24-62 days) Cepheids whose periods and mean magnitudes define tight period-luminosity relations. We use the (V - I) Wesenheit…
The ALHAMBRA Photometric System
Cepa, J.; Infante, L.; Castander, F. J. +20 more
This paper presents the characterization of the optical range of the ALHAMBRA photometric system, a 20 contiguous, equal-width, medium-band CCD system with wavelength coverage from 3500 Å to 9700 Å. The photometric description of the system is done by presenting the full response curve as a product of the filters, CCD, and atmospheric transmission…
Erratum: "Determining Titan's Spin State from Cassini Radar Images"
Iess, Luciano; Cassini RADAR Team; Stiles, Bryan W. +12 more
We previously reported an initial determination of Titan's rotational state from fits to overlapping radar images. We have since discovered a coding error in software used to make these fits, which led to systematic offsets of 1-2 km in recovered positions. While our principal results remain qualitatively unchanged, with this error corrected, the …
A ~ 40 Year Variability Cycle in the Luminous Blue Variable/Wolf-Rayet Binary System HD 5980?
Hillier, D. John; Morrell, Nidia; Gamen, Roberto +3 more
The massive Wolf-Rayet stellar system HD 5980 in the Small Magellanic Cloud entered a sudden and brief ~ 1-3 mag eruptive state in the mid-1990s. The cause of the instability is not yet understood, but mechanisms similar to those in luminous blue variables are suspected. Using a previously unreported set of spectroscopic data obtained in 1955-1967…
Hierarchical Structure Formation and Modes of Star Formation in Hickson Compact Group 31
Hornschemeier, A. E.; Mendes de Oliveira, C.; Young, J. +12 more
The handful of low-mass, late-type galaxies that comprise Hickson Compact Group 31 (HCG 31) is in the midst of complex, ongoing gravitational interactions, evocative of the process of hierarchical structure formation at higher redshifts. With sensitive, multicolor Hubble Space Telescope imaging, we characterize the large population of < 10 Myr …
Discovery of a Faint Companion to Alcor Using MMT/AO 5 µm Imaging
Meyer, Michael R.; Kenworthy, Matthew A.; Mamajek, Eric E. +1 more
We report the detection of a faint stellar companion to the famous nearby A5V star Alcor (80 UMa). The companion has M-band (λ = 4.8 µm) magnitude 8.8 and projected separation 1.''11 (28 AU) from Alcor. The companion is most likely a low-mass (~0.3 M ⊙) active star which is responsible for Alcor's X-ray emission detected by ROSAT …
Deriving Metallicities from the Integrated Spectra of Extragalactic Globular Clusters Using the Near-infrared Calcium Triplet
Spitler, Lee R.; Forbes, Duncan A.; Brodie, Jean P. +3 more
The Ca II triplet (CaT) feature in the near-infrared has been employed as a metallicity indicator for individual stars as well as integrated light of Galactic globular clusters (GCs) and galaxies with varying degrees of success, and sometimes puzzling results. Using the DEIMOS multi-object spectrograph on Keck we obtain a sample of 144 integrated …