Were planets supposedly discovered a long time ago by the "wobble" of a parent star ever shown to be real?

On Sun, 30 May 1999, Barry wrote:

> There has been a flurry of activity over the Lick discoveries of planets
> around single star systems. I was wondering whatever happened to the
> earlier discoveries of a [10 (or 4) Jupiter sized] planet around 61 Cygni
> by K. A. Strand? Diech (USSR) verified
> Strand's findings. Strand (Naval Observatory) also picked up
> indications of planets around U. V. Ceti and Kruger 60 as well. I think
> it was Gatewood who indicated the 61 Cygni system would be the one of the
> easiest to find planets about by the old astrometric (wobble) technique.

Dear Mr. Warmkessel,

I spoke with one of our resident astronomers who works on a planet-search
team. He reports that there are currently no known planets discovered
by astrometry, the measuring of a star's position on the sky. The
problem with this method is that the shifts due to planets are
exceedingly tiny, and ground-based observatories cannot obtain accurate
enough measurements to see movements caused by even the largest planets.
The motions due to Jupiter-sized planets are on the order 1/100 the
star's size on a high-quality astronomical image!

One of the stars you mentioned, UV Ceti, is also a flare star, or a star
that has large flares (like our sun) that can change its magnitude.
Such variations make the astrometry even more difficult. (The flares also
make it hard, if not impossible, to detect planets by current techniques.)

Many astronomers have claimed to have detected planets by their wobbles
on the sky, with perhaps the most famous candidate being Barnard's Star.
In fact, Gatewood has concluded that there is no good evidence to
suggest that planets have been detected with this method.
Planet search teams have dilligently searched many of these systems, and
so far there have not been confirmations of any of the
previously-suggested planet candidates.

You can learn more about the various planet searches from the following
web site:
http://cfa-www.harvard.edu/planets/

Thanks for writing!

Sincerely,
Kurtis Williams

Back to the Ask An Astronomer page.