Wasn't it Eric Chomko who wrote:
Mike Williams ) wrote:
: Wasn't it Eric Chomko who wrote:
:
: Depending on the distance is key. 100s of LY away won't indicate anything
: noticable.

: For this purpose, the distance doesn't make much of a difference. All you need
: is to have an apparent magnitude bright enough to be able to get a good
: spectrum, and a planet that causes a wobble in the star that gives a change in
: the star's radial velocity of a few tens of metres per second.

Thanks for that info. I have been operating on the way things were done
when this work first began. I was a kid when they found the first two
extrasolar planets. That was when the field was in its infancy. At that
time it was stated than only stars in close proximity to our sun (less
than 15 LY) were candidates for planetary discovery. It is obvious that I
need to dig deeper into this as we have come a long way.

: For example, HD330075, HD68988 and HD76700 are all over 160 light years away
and
: we've detected the wobbles caused by their planets.

I vaguely recall a big breakthrough in all this about a decade or so ago
but lack the details. Thanks again.

I've just discovered
http://www.eso.org/outreach/press-re...ages/phot-05d-
03-preview.jpg
which indicates that the furthest exoplanet discovered by the radial
velocity technique is HD47536 with a distance of 396 LY. (The numbers
shown on that image are logarithms of parsecs, e.g. "3.0" indicates a
distance of 1000 parsecs.) Ogle-TR-56b was discovered by observing a
transit, then later confirmed by the radial velocity technique, and that
may well be something like 5000 light years away.


Other methods of detecting exoplanets might be able to find ones that
are further away. There's an unconfirmed planet Q 0957+561 that's so far
away that the galaxy that it was found in hasn't yet been catalogued.

--
Mike Williams
Gentleman of Leisure