Search Publications
Astrometry with the Hubble Space Telescope: Trigonometric Parallaxes of Selected Hyads
Harrison, Thomas E.; Benedict, G. Fritz; McArthur, Barbara E. +1 more
We present absolute parallaxes and proper motions for seven members of the Hyades open cluster, pre-selected to lie in the core of the cluster. Our data come from archival astrometric data from fine guidance sensor (FGS) 3 and newer data for three Hyads from FGS 1r, both white-light interferometers on the Hubble Space Telescope (HST). We obtain me…
Wind Structure and Luminosity Variations in the Wolf-Rayet/Luminous Blue Variable HD 5980
Hillier, D. John; Morrell, Nidia; Gamen, Roberto +3 more
Over the past 40 years, the massive luminous blue variable/Wolf-Rayet system HD 5980 in the Small Magellanic Cloud (SMC) has undergone a long-term S Doradus-type variability cycle and two brief and violent eruptions in 1993 and 1994. In this paper we analyze a collection of UV and optical spectra obtained between 1979 and 2009 and perform CMFGEN m…
Hubble Space Telescope Imaging and Spectral Analysis of Two Brown Dwarf Binaries at the L Dwarf/T Dwarf Transition
Burgasser, Adam J.; Gizis, John E.; Bardalez-Gagliuffi, Daniella C.
We present a detailed examination of the brown dwarf multiples 2MASS J08503593+1057156 and 2MASS J17281150+3948593, both suspected of harboring components that straddle the L dwarf/T dwarf transition. Resolved photometry from Hubble Space Telescope/NICMOS shows opposite trends in the relative colors of the components, with the secondary of 2MASS J…
A Search for Water Vaporization on Ceres
Carry, B.; Mousis, O.; Jehin, E. +5 more
There are hints that the dwarf planet (1) Ceres may contain a large amount of water ice. Some models and previous observations suggest that ice could be close enough to the surface to create a flux of water outward through the regolith. This work aims to confirm a previous detection of OH emission off the northern limb of Ceres with the Internatio…
The Star Formation History of Isolated Dwarf UGC 4879
Held, Enrico V.; Chiboucas, Kristin; Tully, R. Brent +3 more
Recent observations of UGC 4879 with the Advanced Camera for Surveys on the Hubble Space Telescope confirm that it is a nearby isolated dwarf irregular galaxy. We measure a distance of 1.36 ± 0.03 Mpc using the tip of the red giant branch method. This distance puts UGC 4879 beyond the radius of first turnaround of the Local Group and ~700 kpc from…
High-resolution Satellite Imaging of the 2004 Transit of Venus and Asymmetries in the Cytherean Atmosphere
Schneider, Glenn; Pasachoff, Jay M.; Widemann, Thomas
This paper presents the only space-borne optical-imaging observations of the 2004 June 8 transit of Venus, the first such transit visible from Earth since AD 1882. The high-resolution, high-cadence satellite images we arranged from NASA's Transition Region and Coronal Explorer (TRACE) reveal the onset of visibility of Venus's atmosphere and give f…
Mapping Differential Reddening in the Inner Galactic Globular Cluster System
Mateo, Mario; von Braun, Kaspar; Alonso-García, Javier +2 more
A serious limitation in the study of many globular clusters—especially those located near the Galactic center—has been the existence of large and differential extinction by foreground dust. In a series of papers, we intend to map the differential extinction and remove its effects, using a new dereddening technique, in a sample of clusters in the d…
Penetrating the Homunculus—Near-Infrared Adaptive Optics Images of Eta Carinae
Smith, Nathan; Humphreys, Roberta M.; Davidson, Kris +3 more
Near-infrared adaptive optics imaging with the Near-Infrared Coronagraphic Imager (NICI) and NaCO reveal what appears to be a three-winged or lobed pattern, the "butterfly nebula," outlined by bright Brγ and H2 emission and light scattered by dust. In contrast, the [Fe II] emission does not follow the outline of the wings, but shows an …
Hubble Space Telescope Photometry of Globular Clusters in M81
Nantais, Julie B.; Huchra, John P.; Zezas, Andreas +2 more
We perform aperture photometry and profile fitting on 419 globular cluster (GC) candidates with mV <= 23 mag identified in Hubble Space Telescope/Advanced Camera for Surveys BVI imaging, and estimate the effective radii of the clusters. We identify 85 previously known spectroscopically confirmed clusters, and newly identify 136 objec…
V2492 Cygni: The Early Evolution of the 2010 Outburst
Aspin, Colin
We present Gemini-North optical and near-IR observations of a young eruptive star in Cygnus, designated as V2492 Cygni in the General Catalog of Variable Stars. This object is one of two young stars, located within 2 deg of each other, that recently brightened by around 5 mag and were reported as possible new FU Orionis-type variables. The outburs…