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RE: Xi Ursae Majoris
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Xi_Ursae_Majoris 


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Xi Ursae Majoris is a star system in the constellation Ursa Major. 
On May 2, 1780, Sir William Herschel discovered that this was a binary star system, making it the first such system ever discovered. It was the first visual double star for which an orbit was calculated, when it was computed by Félix Savary in 1828.
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WISE J111838.70+312537.9
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Title: A T8.5 Brown Dwarf Member of the Xi Ursae Majoris System
Authors: Edward L. Wright, M. F. Skrutskie, J. Davy Kirkpatrick, Christopher R. Gelino, Roger L. Griffith, Kenneth A. Marsh, Tom Jarrett, M. J. Nelson, H. J. Borish, Gregory Mace, Amanda K. Mainzer, Peter R. Eisenhardt, Ian S. McLean, John J. Tobin, Michael C. Cushing

The Wide-field Infrared Survey Explorer has revealed a T8.5 brown dwarf (WISE J111838.70+312537.9) that exhibits common proper motion with a solar-neighbourhood (8 pc) quadruple star system - Xi Ursae Majoris. The angular separation is 8.5 arc-min, and the projected physical separation is about 4000 AU. The sub-solar metallicity and low chromospheric activity of Xi UMa A argue that the system has an age of at least 2 Gyr. The infrared luminosity and colour of the brown dwarf suggests the mass of this companion ranges between 28 and 58 Jupiter masses for system ages of 2 and 8 Gyr respectively.

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Xi Ursae Majoris
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Title: On the Orbit of Visual Binary ADS 8119 AB ( = 11h18m10s.9 and =+31o31'44".9)
Authors: S.Siregar, D.Hadi Nugroho

Xi UrsaMajoris (xi Uma) historically is one of the most important double star in constellation Ursa Major, found by Sir William Herschel on May, 2, 1780 and the first binary successfully determined by using the principle of two body problem in 1828 by Savary. This star consists of two pair wide binary ADS8119 AB; in this case HD 98231(ADS8119 A) as primary and HD98230 (ADS 8119 B) as secondary. We have collected the observational data consist of separation angular (rho) and position angle (theta) from the observations in 1780 up to 2005 taken from Bosscha Observatory and other Observatories in the world. This paper presents the recent status of orbit binary system ADS 8119. By using Thiele Van den Bos method and empirical formula Strand's Mass-Luminosity relation we have determined the orbit and mass of ADS 8119AB. The result is; Orbital and Physical Element of ADS 8119 AB. Dynamical Elements, Orbit Orientation, Masses-Parallax; P = 60 years, e = 0.426, T = 1935.8, i = 110o9, {Omega} = 104o.7, {\omega} = 117o5, M1 = 1.4Mo, M2 = 1.2Mo, p = 0".122

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