Search Publications
Mid-Infrared Images of Luminous Infrared Galaxies in a Merging Sequence
Gao, Yu; Gruendl, Robert A.; Hwang, Chorng-Yuan +2 more
We report mid-infrared observations of several luminous infrared galaxies (LIGs) carried out with the Infrared Space Observatory. Our sample was chosen to represent different phases of a merger sequence of galaxy-galaxy interaction with special emphasis on early/intermediate stages of merging. The mid-infrared emission of these LIGs shows extended…
Star Counts and the Warped and Flaring Milky Way Disk
Evans, N. Wyn; Flynn, Chris; Gyuk, Geza
This paper reports the star count predictions of warped and flaring models of the outer Milky Way disk. These have been suggested as possible locations of the lenses responsible for the microlensing events toward the Large Magellanic Cloud (LMC). Three such models are investigated in detail, and the theoretical predictions are confronted with Hubb…
Infrared Candidates for the Intense Galactic X-Ray Source GX 17+2
Anderson, Scott F.; Wachter, Stefanie; Margon, Bruce +2 more
We present new astrometric solutions and infrared Hubble Space Telescope observations of GX 17+2 (X1813-140), one of the brightest X-ray sources on the celestial sphere. Despite 30 years of intensive study and the existence of a strong radio counterpart with a subarcsecond position, the object remains optically unidentified. The observed X-ray cha…
Hubble Space Telescope Images and Spectra of the Remnant of SN 1885 in M31
Fesen, Robert A.; Hamilton, Andrew J. S.; Gerardy, Christopher L. +1 more
Near-UV Hubble Space Telescope images of the remnant of SN 1885 (S And) in M31 show a 0.70"+/-0.05" diameter absorption disk silhouetted against M31's central bulge, at SN 1885's historically reported position. The disk's size corresponds to a linear diameter of 2.5+/-0.4 pc at a distance of 725+/-70 kpc, implying an average expansion velocity of …
A Path Integral Approach to the Theory of Heliospheric Cosmic-Ray Modulation
Zhang, Ming
This paper introduces the path integral method, which has been widely used in quantum mechanics and statistical mechanics, into the field of cosmic-ray modulation theory to solve the Fokker-Planck equation for cosmic-ray transport. The path integral approach recognizes that the motion of cosmic rays is a Markov stochastic process. The derivation o…
A Dwarf Irregular Galaxy at the Edge of the Local Group: Stellar Populations and Distance of IC 5152
Minniti, Dante; Zijlstra, Albert A.
We have obtained V- and I-band photometry for about 700 stars in the field of the dwarf irregular galaxy IC 5152, previously considered a possible member of the Local Group. Deep VI color-magnitude diagrams are presented of the main body of this galaxy and of a nearby field. We infer a distance by comparison with the VI color-magnitude diagrams of…
Relative intensity calibration of CDS-GIS detectors on SOHO using a plasma diagnostic technique
Landini, M.; Del Zanna, G.; Landi, E. +3 more
The internal intensity calibration of the Coronal Diagnostic Spectrometer (CDS) - Grazing Incidence Spectrometer (GIS) is studied using the Arcetri diagnostic method. A large number of spectral lines observed by the four GIS detectors in solar active and quiet regions is analysed in order to determine the relative intensity calibration curve of th…
A Near- and Mid-Infrared Study of the Interacting Galaxy Pair UGC 12914/12915: ``Taffy''
Helou, G.; Condon, J. J.; Jarrett, T. H. +2 more
We report on an infrared 1 to 17 µm study of the nearby (cz=4600 km s-1) interacting spiral galaxy system UGC 12914/12915, using the ground-based Palomar 200 inch (5 m) telescope and PFIRCAM near-infrared detector and space-based mid-infrared imaging and spectral observations using ISOCAM and PHT-S on the Infrared Space Observator…
The Radio Emission of the Seyfert Galaxy NGC 7319
Yoshida, Michitoshi; Wilson, Andrew S.; Aoki, Kentaro +1 more
We present VLA maps of the Seyfert 2 galaxy NGC 7319 at 3.6, 6, and 20 cm. Subarcsecond resolution is achieved at 3.6 and 6 cm. The radio emission exhibits a triple structure on a scale of ~4" (1.7 kpc). All three components have steep spectra, consistent with synchrotron radiation. We have also analyzed an HST archival, broad-band red image, whic…
The steep spectrum quasar PG1404+226 with ASCA, HST and ROSAT
Comastri, A.; Komossa, S.; Crane, P. +1 more
We present and discuss our observations of the Narrow Line quasar PG1404+226 (zem = 0.098) with ASCA and HST, and a re-analysis of our earlier observations with ROSAT. The soft X-ray spectrum is very steep and displays an absorption feature (edge or line at ~ 1.1 keV). We have applied a variety of models to the ASCA and ROSAT spectra wi…