Search Publications
Surface brightness profiles and structural parameters for globular clusters in the Fornax and Sagittarius dwarf spheroidal galaxies
Mackey, A. D.; Gilmore, G. F.
We present radial surface brightness profiles for all five globular clusters in the Fornax dwarf spheroidal galaxy, and for the four present members of the Sagittarius dwarf spheroidal galaxy. These profiles are derived from archival Hubble Space Telescope observations, and have been calculated using the same techniques with which we measured prof…
Formation scenarios for the young stellar associations between galactic longitudes l = 280degr - 360degr
Dias, W. S.; Lépine, J. R. D.; Sartori, M. J.
We investigate the spatial distribution, the space velocities and age distribution of the pre-main sequence (PMS) stars belonging to Ophiuchus, Lupus and Chamaeleon star-forming regions (SFRs), and of the young early-type star members of the Scorpius-Centaurus OB association. These young stellar associations extend over the galactic longitude rang…
Discovery of a magnetic field in the Slowly Pulsating B star zeta Cassiopeiae
Frémat, Y.; Neiner, C.; Wiersema, K. +5 more
The Nuclear Regions of the Seyfert Galaxy NGC 4151: Parsec-Scale H I Absorption and a Remarkable Radio Jet
Mundell, C. G.; Pedlar, A.; Wrobel, J. M. +1 more
Sensitive high angular and linear resolution radio images of the 240 pc radio jet in NGC 4151, imaged at linear resolutions of 0.3-2.6 pc using the VLBA and phased VLA at λ21 cm, are presented and reveal for the first time a faint, highly collimated jet (diameter <~1.4 pc) underlying discrete components, seen in lower resolution MERLIN and VLA …
A Survey for Circumstellar Disks around Young Substellar Objects
Tokunaga, Alan T.; Liu, Michael C.; Najita, Joan
We have completed the first systematic survey for disks around spectroscopically identified young brown dwarfs and very low mass stars. For a sample of 38 very cool objects in IC 348 and Taurus, we have obtained L'-band (3.8 µm) imaging with sufficient sensitivity to detect objects with and without disks. The sample should be free of selecti…
The INTEGRAL IBIS/ISGRI System Point Spread Function and Source Location Accuracy
Goldoni, P.; Rodriguez, J.; Foschini, L. +5 more
The imager on board INTEGRAL (IBIS) presently provides the most detailed sky images ever obtained at energies above 30 keV. The telescope is based on a coded aperture imaging system which allows to obtain sky images in a large field of view (29deg x 29deg) with an angular resolution of 12'. The System Point Spread Function of…
Chandra X-Ray Observations of the Spiral Galaxy M81
Wu, Kinwah; Tennant, Allyn F.; Swartz, Douglas A. +3 more
A Chandra X-Ray Observatory ACIS-S imaging observation is used to study the population of X-ray sources in the nearby Sab galaxy M81 (NGC 3031). A total of 177 sources are detected with 124 located within the D25 isophote to a limiting X-ray luminosity of ~3×1036 ergs s-1. Source positions, count rates, luminositie…
XMM-NEWTON High resolution spectroscopy of NGC 5548
Kaastra, J. S.; Steenbrugge, K. C.; de Vries, C. P. +1 more
We analyze a 137 ks exposure X-ray spectrum of the Seyfert 1 galaxy NGC 5548 obtained with the XMM-Newton Reflection Grating Spectrometer. Due to the long exposure time, the spectrum is of higher statistical quality than the previous observations of this AGN. Therefore, we detect for the first time in NGC 5548 inner-shell transitions from O Iii to…
An Imaging Survey of Early-Type Barred Galaxies
Erwin, Peter; Sparke, Linda S.
This paper presents the results of a high-resolution imaging survey, using both ground-based and Hubble Space Telescope images, of a complete sample of nearby barred S0-Sa galaxies in the field, with a particular emphasis on identifying and measuring central structures within the bars: secondary bars, inner disks, nuclear rings and spirals, and of…
An Extensive Census of Hubble Space Telescope Counterparts to Chandra X-Ray Sources in the Globular Cluster 47 Tucanae. I. Astrometry and Photometry
Heinke, Craig O.; Gilliland, Ronald L.; Edmonds, Peter D. +1 more
We report in this study of 47 Tucanae the largest number of optical identifications of X-ray sources yet obtained in a single globular cluster. Using deep Chandra ACIS-I imaging and extensive Hubble Space Telescope studies with Wide Field Planetary Camera 2 (WFPC2; including a 120 orbit program giving superb V and I images), we have detected optic…