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Wide-Field CCD Photometry of the Globular Cluster M92
Lee, Hyung Mok; Lee, Myung Gyoon; Fahlman, Gregory G. +1 more
We present wide-field CCD photometry of the Galactic globular cluster M92 obtained in the V and I bands with the CFH12K mosaic CCD at the Canada-France-Hawaii Telescope. A well-defined color-magnitude diagram is derived down to 5 mag fainter than the cluster main-sequence turnoff. After removing the background contribution, we obtain luminosity an…
XMM-Newton Observations of Two Broad Absorption Line QSOs: Q1246-057 and SBS 1542+541
Elvis, M.; Grupe, D.; Mathur, S.
We report on the results of XMM-Newton observations of two broad absorption line quasars (BAL QSOs), Q1246-057 and SBS 1542+541. The unprecedented sensitivity of XMM-Newton allows spectral analysis of these X-ray-weak sources. The X-ray spectral data of these sources can be fitted by a power law with αX=1.0-1.2 and either a partially co…
Analysis of Stellar Occultation Data. II. Inversion, with Application to Pluto and Triton
Elliot, J. L.; Person, M. J.; Qu, S.
We present a method for obtaining atmospheric temperature, pressure, and number density profiles for small bodies through inversion of light curves recorded during stellar occultations. This method avoids the assumption that the atmospheric scale height is small compared with the radius of the body, and it includes the variation of gravitational a…
Stellar Crowding and the Science Case for Extremely Large Telescopes
Olsen, Knut A. G.; Blum, Robert D.; Rigaut, François
We present a study of the effect of crowding on stellar photometry. We develop an analytical model through which we are able to predict the error in magnitude and color for a given star for any combination of telescope resolution, stellar luminosity function, background surface brightness, and distance. We test our predictions with Monte Carlo sim…
High Proper Motion Features in the Central Orion Nebula
O'Dell, C. R.; Doi, Takao
The brightest portion of the Orion Nebula has been reimaged with the Hubble Space Telescope in Hα, [N II], and [O III]. Comparison with earlier Wide Field Planetary Camera 2 images going back as much as 8 yr has allowed determination of tangential velocities (proper motions) down to about 10 km s-1 for a variety of sources. Multiple out…
High-Resolution Near-Infrared Imaging and Polarimetry of Four Proto-Planetary Nebulae
Kwok, Sun; Hrivnak, Bruce J.; Su, Kate Y. L. +1 more
High-resolution near-infrared Hubble Space Telescope (HST) NICMOS (F160W, F222M) images and polarization (2 µm) observations were made of four bipolar proto-planetary nebulae (PPNs): IRAS 17150-3224, 17441-2411, 17245-3951, and 16594-4656. The first three of these are viewed nearly edge-on, and for the first time the central stars in them ar…
Two Embedded Young Stellar Objects in NGC 2264 with FU Orionis Characteristics
Reipurth, Bo; Aspin, Colin
We report the discovery of two young stars in the NGC 2264 star-forming molecular cloud whose physical and morphological characteristics are similar to FU Orionis objects. The objects form a close pair and exhibit a curved reflection nebula in the near-IR. The brighter of the two stars, AR 6A, is optically visible but considerably reddened, has a …
The Recent Evolution of the Dwarf Starburst Galaxy NGC 625 from Hubble Space Telescope Imaging
Cannon, John M.; Skillman, Evan D.; Miller, Bryan W. +3 more
New Hubble Space Telescope WFPC2 imaging of the dwarf starburst galaxy NGC 625 is presented. These data, which are 80% complete to V and I magnitudes of 26.0 and 25.3, respectively, allow us to study the recent star formation history of NGC 625. Using outlying red giant stars, we derive a tip of the red giant branch (TRGB) distance modulus of 27.9…
Searching for Embedded Super-Star Clusters in IC 4662, NGC 1705, and NGC 5398
Johnson, Kelsey E.; Indebetouw, Rémy; Pisano, D. J.
Radio observations of IC 4662, NGC 5398, and NGC 1705 are used in combination with optical images to search for extremely young star clusters that are still embedded in their birth material. Radio data were obtained at 3 and 6 cm using the Australia Telescope Compact Array, and optical data were retrieved from the Hubble Space Telescope (HST) arch…
A Point-Source Excess in Abell 1185: Intergalactic Globular Clusters?
Jordán, Andrés; Marzke, Ronald O.; Côté, Patrick +1 more
Deep imaging with WFPC2 and the Hubble Space Telescope has been used to search for a population of intergalactic globular clusters (GCs) belonging to A1185, a richness class I cluster at cz=9800 km s-1. The field is noteworthy in that contains no bright galaxies and yet is centered on the peak of the cluster's X-ray surface brightness d…