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Another Faint Ultraviolet Object Associated with a Globular Cluster X-Ray Source: The Case of M92
Ferraro, Francesco R.; Paltrinieri, Barbara; Fusi Pecci, Flavio +2 more
The core of the metal-poor galactic globular cluster M92 (NGC 6341) has been observed with Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope through visual, blue, and mid-UV filters in a program devoted to studying the evolved stellar population in a selected sample of galactic globular clusters. In the UV (m255, m
Transient Effects in ISOPHOT Data: Status of Modelling and Correction Procedures
Gabriel, C.; Acosta-Pulido, J. A.; Castañeda, H. O.
The calibration of ISOPHOT observations is hampered in many cases by the transient response of the detectors. Here we outline the behaviour observed in flight for the different ISOPHOT detectors. We also present some of the procedures which are currently used to correct transient effects and their implementation in the ISOPHOT Interactive Analysis.
Some Features of Manifestations of Coronal Holes in Microwave Emission
Grechnev, Victor V.; Krissinel, Boris B.; Kuznetsova, Svetlana M. +4 more
Using observational data from the SSRT, we have investigated the behavior of four mid- and low-latitude coronal holes. The coronal holes under study appeared as regions of decreased emission intensity relative to the quiet Sun level totally or partially coincident with holes in EUV emission. Difference in the electron density and temperature in di…
Spiral and irregular galaxies in the Hubble Deep Field North. Comparison with early types and implications for the global SFR density
Rodighiero, G.; Franceschini, A.; Granato, G. L. +2 more
We analyze a morphologically-selected complete sample of 52 late-type (spiral and irregular) galaxies in the Hubble Deep Field North with total K-magnitudes brighter than K=20.47 and typical redshifts z ~ 0.5 to 1.4. This sample exploits in particular the ultimate imaging quality achieved by HST in this field, allowing us to clearly disentangle th…
An analysis of the Ap binary HD 81009
Wade, G. A.; Bohlender, D. A.; Mathys, G. +3 more
We present a detailed investigation of the orbit, component characteristics and magnetic field of the single spectrum (SB1), visual Ap binary HD 81009. By simultaneously modeling new and archival radial velocity measurements and new and archival speckle interferometric measurements (obtained with the CHARA array) we obtain a unique model of the or…
Systematic Differences between the FK5 Proper-Motion System and Hipparcos
Zhu, Zi
We present an intensive analysis of the FK5 proper-motion system via the two large astrographic catalogs, the PPM and ACRS catalogs, compared with the Hipparcos proper motions. Region-, magnitude-, and color-dependent systematic errors in the PPM and ACRS proper motions are found and exhibit similar tendencies for both catalogs. The term of the gl…
Gas Dynamics in Planetary Nebulae: From Macro-structures to FLIERs
Perinotto, Mario
Purpose of this paper is to clarify how Planetary Nebulae (PNe) are very interesting laboratories to study cosmic gas dynamics. I first recall the history of PNe which are generated from low and intermediate mass stars through successive mass loss processes starting in the Reg Giant phase of evolution and continuing also after the termination of t…
Ultraviolet Imaging of the Galaxy Cluster CL 0939+4713 (Abell 851) at z=0.41
Dressler, Alan; Cappellari, Michele; Bertola, Francesco +3 more
The first UV F300W and F218W WFPC2 observations of the rich galaxy cluster CL 0939+4713 at z=0.41 are presented and discussed. UV/optical two-color and color-magnitude diagrams of the sources detected in the F300W waveband are constructed. Thanks to preexisting Hubble Space Telescope (HST) optical images of the same field, a morphological classifi…
Interpretation of the UV spectrum of some stars with little reddening
Zagury, Frédéric
The UV spectrum of a few reddened stars will be decomposed into two terms. One is the direct starlight, F ★,λ0 e-τ λ, which is the product of the flux of the star corrected for interstellar extinction, F★, λ0, and of the extinction e - τλ. The second is starlig…
Orbital period variation in close binaries from radial velocity data and magnetic activity cycles. I. AR Lacertae: The test case
Lanza, A. F.; Frasca, A.
We check the possibility of detecting orbital period changes in non-eclipsing close binaries by means of spectroscopic orbit determinations. In order to test our method, we selected the eclipsing binary AR Lacertae for which the spectroscopically determined epochs of superior conjuctions can be compared with those provided by the light minima phot…