Search Publications
The Top 10 Spitzer Young Stellar Objects in 30 Doradus
Walborn, Nolan R.; Barbá, Rodolfo H.; Sewiło, Marta M.
The most luminous Spitzer point sources in the 30 Doradus triggered second generation are investigated coherently in the 3-8 µm region. Remarkable diversity and complexity in their natures are revealed. Some are also among the brightest JHK sources, while others are not. Several of them are multiple when examined at higher angular resolution…
Optical and X-Ray Studies of 10 X-Ray-selected Cataclysmic Binaries
Thorstensen, John R.; Halpern, Jules
We report on ground-based optical observations of 10 cataclysmic binaries that were discovered through their X-ray emission. Time-resolved radial velocity spectroscopy yields unambiguous orbital periods for eight objects and ambiguous results for the remaining two. The orbital periods range from 87 minutes to 9.38 hr. We also obtained time-series …
An Echo of Supernova 2008bk
Van Dyk, Schuyler D.
I have discovered a prominent light echo around the low-luminosity Type II-plateau supernova (SN) 2008bk in NGC 7793, seen in archival images obtained with the Wide Field Channel of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST). The echo is a partial ring, brighter to the north and east than to the south and west. The a…
The Snapshot Hubble U-band Cluster Survey (SHUCS). I. Survey Description and First Application to the Mixed Star Cluster Population of NGC 4041
Bastian, N.; Larsen, S. S.; Gallagher, J. S. +9 more
We present the Snapshot Hubble U-band Cluster Survey (SHUCS), a project aimed at characterizing the star cluster populations of 10 nearby galaxies (d < 23 Mpc, half within ≈12 Mpc) through new F336W (U-band equivalent) imaging from Wide Field Camera 3, and archival BVI-equivalent data with the Hubble Space Telescope. Completing the UBVI baselin…
A H I Imaging Survey of Asymptotic Giant Branch Stars
Le Bertre, T.; Matthews, L. D.; Johnson, M. C. +1 more
We present an imaging study of a sample of eight asymptotic giant branch stars in the H I 21 cm line. Using observations from the Very Large Array, we have unambiguously detected H I emission associated with the extended circumstellar envelopes of six of the targets. The detected H I masses range from M H I ≈ 0.015-0.055 M solar
Herschel Observations of Cataclysmic Variables
Harrison, Thomas E.; Campbell, Ryan K.; Tappert, Claus +2 more
We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 µm. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE observations to construct spectral energy distributions for all of the targets. For the two dw…
Meter-sized Moonlet Population in Saturn's C Ring and Cassini Division
Colwell, Joshua E.; Esposito, Larry W.; Lewis, Mark C. +1 more
Stellar occultations observed by the Cassini Ultraviolet Imaging Spectrograph reveal the presence of transparent holes a few meters to a few tens of meters in radial extent in otherwise optically thick regions of the C ring and the Cassini Division. We attribute the holes to gravitational disturbances generated by a population of ~10 m boulders in…
Hipparcos Photocentric Orbits of 72 Single-lined Spectroscopic Binaries
Ren, Shulin; Fu, Yanning
By fitting the Hipparcos Intermediate Astrometric Data (HIAD), photocentric orbits can be obtained for the single-lined spectroscopic binaries (SB1s). In previous work, a simplifying approximation used in the fitting process was that the photocenter coincides with the primary, but simple arguments based on a mass-luminosity relation show that this…
HST/WFC3 Observations of Low-mass Globular Clusters AM 4 and Palomar 13: Physical Properties and Implications for Mass Loss
Dolphin, Andrew E.; Smith, Graeme H.; Grillmair, Carl J. +4 more
We investigate the loss of low-mass stars in two of the faintest globular clusters known, AM 4 and Palomar 13 (Pal 13), using HST/WFC3 F606W and F814W photometry. To determine the physical properties of each cluster—age, mass, metallicity, extinction, and present day mass function (MF)—we use the maximum likelihood color-magnitude diagram (CMD) fi…
The Vast Population of Wolf-Rayet and Red Supergiant Stars in M101. I. Motivation and First Results
Drissen, Laurent; Moffat, Anthony F. J.; Shara, Michael M. +3 more
Assembling a catalog of at least 10,000 Wolf-Rayet (W-R) stars is an essential step in proving (or disproving) that these stars are the progenitors of Type Ib and Type Ic supernovae. To this end, we have used the Hubble Space Telescope (HST) to carry out a deep, He II optical narrowband imaging survey of the ScI spiral galaxy M101. Almost the enti…