Search results
Results From The WOW.Com Content Network
Pages in category "Free software programmed in C" The following 200 pages are in this category, out of approximately 633 total. This list may not reflect recent changes .
HD 141569 is an isolated [5] Herbig Ae/Be star [6] of spectral class A2Ve [7] approximately 364 light-years away in the constellation of Libra. The primary star has two red dwarf companions (orbiting each other) at about nine arcseconds. In 1999, a protoplanetary disk was discovered around the star.
The use of the parsec as a unit of distance follows naturally from Bessel's method, because the distance in parsecs can be computed simply as the reciprocal of the parallax angle in arcseconds (i.e.: if the parallax angle is 1 arcsecond, the object is 1 pc from the Sun; if the parallax angle is 0.5 arcseconds, the object is 2 pc away; etc.).
A parsec is the distance from the Sun to an astronomical object that has a parallax angle of one arcsecond (not to scale). The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres (19.2 trillion miles).
an object of diameter 45 866 916 km at one light-year, an object of diameter one astronomical unit (149 597 870.7 km) at a distance of one parsec, per the definition of the latter. [7] One milliarcsecond is about the size of a half dollar, seen from a distance equal to that between the Washington Monument and the Eiffel Tower.
The mission is operated by Pennsylvania State University as part of NASA's Medium Explorer program (MIDEX). The burst detection rate is 100 per year, with a sensitivity ~3 times fainter than the BATSE detector aboard the Compton Gamma Ray Observatory. The Swift mission was launched with a nominal on-orbit lifetime of two years.
This number is likely much higher, due to the sheer number of stars needed to be surveyed; a star approaching the Solar System 10 million years ago, moving at a typical Sun-relative 20–200 kilometers per second, would be 600–6,000 light-years from the Sun at present day, with millions of stars closer to the Sun.
Overview over the radio structure of Centaurus A. The whole radio emitting region extends about 1.8 million light years (about 8° degrees in the sky). Through observations with the VLBI technique structures of the jet and the core smaller than a light year could be resolved (corresponding to a resolution of 0.68 x 0.41 milli-arcseconds. [53])