Search Publications
Complete analysis of the subgiant stellar system: HIP 102029
Mardini, Mohammad K.; Al-Wardat, Mashhoor A.; Abu-Alrob, Enas M. +2 more
In this work, we present a detailed analysis of the individual components of the visual binary system HIP 102029 (R.A. = 20:40:35.32, Dec. = +15:38:35.63). The system was discovered during the European Space Agency Hipparcos mission and has a separation of 220 mas. The analysis uses the ORBITX code and Al-Wardat's method to estimate the orbital, a…
The 24 Aqr triple system: A closer look at its unique high-eccentricity hierarchical architecture
Horch, Elliott P.; Abushattal, Ahmad A.; Al-Wardat, Mashhoor A. +4 more
As its periastron passage occurred during the third quarter of 2020, system 24 Aqr is of particular significance. New visual solutions for the latest speckle interferometry observations collected by the Lowell Discovery Telescope (LTD) with its new QWSSI speckle camera are presented here. A variety of techniques were used to analyze the system, in…
Trigonometric parallax discrepancies in space telescopes measurements I: The case of the stellar binary system Hip 84976
Al-Wardat, Mashhoor A.; Hussein, Abdallah M.; Widyan, Hatem +1 more
In addition to the complete set of fundamental parameters of its individual components, we present the solution for the discrepancy between the two main astrometric space telescopes Gaia and Hipparcos, in their measurements of the trigonometric parallax for the stellar binary system Hip 84976. In our analysis of the system, we followed Al-Wardat's…
A novel star identification technique robust to high presence of false objects: The Multi-Poles Algorithm
Schiattarella, Vincenzo; Spiller, Dario; Curti, Fabio
This work proposes a novel technique for the star pattern recognition for the Lost in Space, named Multi-Poles Algorithm. This technique is especially designed to ensure a reliable identification of stars when there is a large number of false objects in the image, such as Single Event Upsets, hot pixels or other celestial bodies. The algorithm ide…
X-ray emission of young SN Ia remnants as a probe for an explosion model
Lundqvist, P.; Sorokina, E. I.; Blinnikov, S. I. +1 more
We present results of hydrodynamical simulations of young supernova remnants. To model the ejecta, we use several models (discussed in the literature) of type Ia supernova explosions with different abundances. Our hydro models are one-dimensional and spherically symmetrical, but they take into account ionization kinetics with all important process…
The mean stellar parameters from IUE and hipparcos data
Niemczura, E.; Cugier, H.; Daszyńska, J.
Scientific requirements for very accurate astrometry
Turon, C.; Kovalevsky, J.
Two types of accurate astrometric data are considered:
1) Survey astrometry providing absolute parallaxes and annual proper motions with an accuracy of 2 milli-arcsec, to a few tenth of a milli-arcsec. Parallax determinations will advance our basic knowledge of the Universe by giving the necessary strong foundations for the first steps of the…Hipparcos calibration
Schrijver, Hans
The methods and results of various Hipparcos in-flight calibrations are described. The geometrical calibrations allow the determination of the instrument distortions in the main field of view to better than a milli-arcsecond. A systematic decrease of the basic angle at a rate of two milli-arcseconds per month has been measured during the first 7 m…
A comparison between two strategies of data reduction for the Hipparcos project
Lattanzi, M. G.; Bucciarelli, B.; Sarasso, M. +2 more
Two different strategies for reducing HIPPARCOS data are directly compared and their respective impact on the final precision of the HIPPARCOS Catalog is evaluated. These strategies are the FAST (Fundamental Astronomy by Space Techniques) Consortium's Baseline and GLOBUS procedures. The Baseline is already operating on satellite data; GLOBUS was i…
Hipparcos: Revised mission overview
Perryman, M. A. C.
The Hipparcos astrometry satellite was launched on 8 August 1989, and after spacecraft and payload commissioning, commenced the routine data acquisition phase on 26 November 1989. Having failed to reach its planned geostationary orbit, major revisions in the mission operations had to be performed, although the impact on the final mission accuracie…