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(Quick question.)
Barnard's star has radial speed ,
proper motion ,
and parallax 0.546''.
Parallax is the angle by which a star shifts
against its background when measured from
the two extreme points
of a baseline of ,
i.e. observing the star from Earth three months apart.
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What is the distance to Barnard's star in pc?
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What is the tangential speed of Barnard's star?
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What is the magnitude and direction of the velocity
of Barnard's star?
Express the direction as an angle with respect to the
line-of-sight.
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How far, in pc, will Barnard's star be from Earth at its point
of closest approach?
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In how many years will it reach its point of closest approach?
A piece of trivia: before the recent discovery
of extrasolar planets using the Doppler-recoil technique,
Barnard's star was a favourite target of astrometric
planet searches because of its proximity to Earth.
(An astrometric search looks for a wobble
in the path of the star across the sky.)
Several of these searches even claimed success, though without
confirmation. It is now known, from Doppler-recoil,
that Barnard's star does not have planets --
at least, not massive ones like Jupiter.
Astronomy 7
Tue Oct 19 13:15:33 PDT 1999