BARNARD'S STAR

Barnard's Star moves against the background of more distant stars faster than any other star that we know about.

It moves at the amazing speed of 10.3 "arc/year, which corresponds to a lunar diameter in only 173 years.  For stars, that's fast!

A typical amateur's CCD and telescope system can have an image scale of 0.7 "arc/pixel, and a plate-solved accuracy for each star of ~ 0.2 "arc. Therefore, it is theoretically possible to use CCD images to measure a star's location with respect to other stars with an accuracy that should enable Barnard's Star's motion in only a month or two.  This web page records a few images made over a decade, and the expected motion of 103 "arc in that time is readily apparent. 


Figure 6. Barnard's Star, 2012.08.26, using a 14-inch Meade LX-200GPS, r'-band filter, 123 stack of 5-second exposures. FWHM = 2.6 "arc. FOV = 26 x 15 'arc. Barnard's Star on this date (red cross) is located at 17:57:47.78 +04:43:47.4. It's location in 2002 is shown by a yellow circle.

The next image was made 10 years earlier, in 2002.


Figure 2
. Region of sky where Barnard's Star has been during the past 50 years.  The dimensions of this image are 27 x 14 'arc.  The full moon has a diameter that averages about 30 'arc, so this image has a width approximately equal to that of the full moon.  North is "up."  Barnard's motion has a direction that is 5 degrees clockwise from north (i.e., position angle = 5 degrees).  Barnard's Star has a magnitude of 9.6.  The faintest stars are 18th magnitude. Sum of images taken 2002.04.21, 2002.05.30 and 2002.06.14.  [Meade LX200 10-inch SCT, f/6.3, SBIG ST-8E CCD, TT CFW, unfiltered, Santa Barbara, CA residence]

Figure 3.  3-frame "movie" of Barnard's Star motion.  Northward (upward) motion is captured by as small-area crop of the April 21, May 30 and June 14 images.  Digital development was used to reduce saturation effects (which leads to a dark ring surrounding the bright stars).  Image dimensions are 10.4 x 7.0 'arc.  Barnard's Star moves a mere 1.9 "arc during this 53-day interval. Differences in image sharpness are due to atmospheric seeing changes as well as observing technique and analysis improvements.



Figure 4.  Plot of right ascension and declination of Barnard's Star (offsets with respect to a nearby reference star), versus date.  Residuals off the fitted line are 0.20 and 0.17 "arc.


Figure 5.  Direction of motion is north-northeast.  The position angle of this direction is 23 +/- 8 degrees (versus a true 5 +/- 1 degree).  The rate of motion is 12.64 +/- 2.3 "arc/year (close to the generally cited 12.29 "arc/year).

You may learn more about Barnard's Star at Frommer.and other links on that web page.

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Webmaster: Bruce L. Gary. This site opened:  May 26, 2002 Last Update:  2012.08.26