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A Volume-limited Photometric Survey of 114 γ Doradus Candidates
Henry, Gregory W.; Fekel, Francis C.; Henry, Stephen M.
We have carried out a photometric survey of a complete, volume-limited sample of γ Doradus candidates. The sample was extracted from the Hipparcos catalog and consists of 114 stars with colors and absolute magnitudes within the range of known γ Doradus stars and that also lie within a specified volume of 266,600 pc3. We devoted one year…
Properties of the H II Region Populations of M51 and NGC 4449 from Hα Images with the Advanced Camera for Surveys on the Hubble Space Telescope
Beckman, John E.; Gutiérrez, Leonel; Buenrostro, Valeria
We have used images from the Advanced Camera for Surveys on the Hubble Space Telescope in Hα, and in the neighboring continuum, to produce flux-calibrated images of the large spiral galaxy M51 and the dwarf irregular NGC 4449. From these images, we have derived the absolute luminosities in Hα, the areas, and the positions with respect to the galac…
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 …