![]() ![]() We discuss astrophysical puzzles presented by the Sirius system, including the probability that the two stars must have interacted in the past, even though there is no direct evidence for this and the orbital eccentricity remains high.īased in part on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, and from the Mikulski Archive for Space Telescopes at STScI, which are operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. The age of Sirius A based on these models is about 237-247 Myr, with uncertainties of ☑5 Myr, consistent with that of the WD companion. Measuring Proper Motion via High Resolution Imaging with HST or Ground-Based AO The first one is applicable when both the lens and the source are stellar objects, that is, to take a snapshot with very high precision astrometry long after the event. HST imaging, conducted at eight epochs over an interval of six years, reveals a clear relativistic astrometric deflection of the background stars apparent position. Combined with the parallax and the motion of the A component, these elements yield dynamical masses of 2.063+/- 0.023 ⊙, to fit its location on the luminosity-radius plane. ![]() Using images obtained over nearly two decades with the Hubble Space Telescope (HST), along with photographic observations covering almost 20 years and nearly 2300 historical measurements dating back to the 19th century, we determine precise orbital elements for the visual binary. Sirius, the seventh-nearest stellar system, is a visual binary containing the metallic-line A1 V star Sirius A, the brightest star in the sky, orbited in a 50.13 year period by Sirius B, the brightest and nearest white dwarf (WD). We report new milliarcsecond accurate radio positions in the International Celestial Reference Frame for 74 Southern Hemisphere radio sources obtained by a continuing VLBI research program in. ![]()
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