Search Publications
The Circumstellar Environments of NML Cygni and the Cool Hypergiants
Humphreys, Roberta M.; Marengo, Massimo; Schuster, Michael T.
We present high-resolution HST WFPC2 images of compact nebulosity surrounding the cool M-type hypergiants NML Cyg, VX Sgr, and S Per. The powerful OH/IR source NML Cyg exhibits a peculiar bean-shaped asymmetric nebula that is coincident with the distribution of its H2O vapor masers. We show that NML Cyg's circumstellar envelope is likel…
The Orbits of Saturn's Small Satellites Derived from Combined Historic and Cassini Imaging Observations
Porco, C. C.; Spitale, J. N.; Jacobson, R. A. +1 more
We report on the orbits of the small, inner Saturnian satellites, either recovered or newly discovered in recent Cassini imaging observations. The orbits presented here reflect improvements over our previously published values in that the time base of Cassini observations has been extended, and numerical orbital integrations have been performed in…
The Effects of Space Weathering at UV Wavelengths: S-Class Asteroids
Vilas, Faith; Hendrix, Amanda R.
We present evidence that space weathering manifests itself at near-UV wavelengths as a bluing of the spectrum, in contrast with the spectral reddening that has been seen at visible-near-IR wavelengths. Furthermore, the effects of space weathering at UV wavelengths tend to appear with less weathering than do the longer wavelength effects, suggestin…
Faint Infrared Extragalactic Survey: Data and Source Catalog of the MS 1054-03 Field
Förster Schreiber, N. M.; Rix, H. -W.; van der Werf, P. +8 more
We present deep near-infrared Js-, H-, and Ks-band imaging of a field around MS 1054-03, a massive cluster at z=0.83. The observations were carried out with the ISAAC instrument at the ESO Very Large Telescope (VLT) as part of the Faint Infrared Extragalactic Survey (FIRES). The total integration time amounts to 25.9 hr in J<…
Optical and X-Ray Identification of Faint Radio Sources in the GOODS CDF-S Advanced Camera for Surveys Field
Koekemoer, A.; Mobasher, B.; Norris, R. P. +2 more
We present optical and X-ray identifications for the 64 radio sources in the Great Observatories Origins Deep Survey Chandra Deep Field-South Advanced Camera for Surveys (ACS) field revealed in the Australia Telescope Compact Array 1.4 GHz survey of the Chandra Deep Field-South. Optical identifications are made using the ACS images and catalogs, w…
Irradiated and Bent Jets in the Orion Nebula
Smith, Nathan; Bally, John; Walawender, Josh +1 more
We present new images and proper-motion measurements of irradiated outflows from young stars in the outskirts of the Orion Nebula obtained with the Advanced Camera for Surveys onboard the Hubble Space Telescope. The images reveal many new outflows and new details in previously detected flows. The large-scale bipolar flows such as HH 502, 505, 874,…
Hot Populations in M87 Globular Clusters
Kundu, Arunav; Frogel, Jay A.; O'Connell, Robert W. +5 more
To explore the production of UV-bright stars in old, metal-rich populations like those in elliptical galaxies, we have obtained Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph far- and near-UV photometry of globular clusters (GCs) in four fields in the giant elliptical (gE) galaxy M87. To a limit of mFUV~25 we detect a…
The Star Formation Histories of the Bulge and Disk of M31 from Resolved Stars in the Near-Infrared
Massey, Philip; Olsen, Knut A. G.; Blum, Robert D. +4 more
We discuss H and K observations of three fields in the bulge and disk of M31 obtained with the ALTAIR adaptive optics system and NIRI instrument on Gemini North. These are the highest resolution and deepest near-infrared observations obtained to date of the inner regions of M31 and demonstrate the promise of ground-based adaptive optics for studyi…
Dynamical Evolution of the TW Hydrae Association
Ortega, V. G.; de la Reza, R.; Jilinski, E.
Using Galactic dynamics we have determined the age of the low-mass post-T Tauri stars in the TW Hya Association (TWA). To do so we applied the method of Ortega and coworkers to five stars of the association with Hipparcos-measured distances (TWA 1, TWA 4, TWA 9, TWA 11, and TWA 19). The method is based on the calculation of the past three-dimensio…
Spectral Statistics and Local Luminosity Function of a Complete Hard X-Ray Sample of the Brightest Active Galactic Nuclei
Ishisaki, Y.; Ueda, Y.; Miyaji, T. +2 more
We have measured the X-ray spectral properties of a complete flux-limited sample of bright active galactic nuclei (AGNs) from the HEAO-1 all-sky catalogs to investigate their statistics and provide greater constraints on the bright end of the hard X-ray luminosity function (HXLF) and the AGN population synthesis model of the X-ray background. Spec…