From: rfentima@ub.d.umn.edu (Robert Fentiman)
Newsgroups: alt.alien.visitors
Subject: Re: The Cursor Speaks Out!
Date: 24 Jan 1993 16:23:06 -0600
Organization: University of Minnesota, Duluth
NNTP-Posting-Host: ub.d.umn.edu

In article <1993Jan24.184626.27457@netcom.com> payner@netcom.com (Rich Payne) writes:
:In article <1jn5jpINNdvh@usenet.INS.CWRU.Edu> smg6@po.CWRU.Edu (Stanley M. Golem) writes:
:>
:>While you may be correct in saying that there are no known planets
:>associated with stars other than the sun, this is true only in that
:>we have no absolute proof that such planets exist.
:>
:>This is misleading.  Absolute proof in the form of a space probe or
:>direct observation of another solar system is quite impossible given
:>the limitations of modern technology.

:>There is considerable indirect proof of which you may not be aware.
:>Epsilon Eridani exhibits a "wobble" in its path through the celestial
:>sphere which can be easily explained only by the presence of one or
:>more "companions" with a total mass about six times that of Jupiter.
:>Barnard's star (one of the closest to us) is thought to have two com-
:>panions of 0.9 and 0.6 Jupiter masses.

:Detection of a wobble by photographic means has always seemed a bit
:suspicious to me. It seems that the error must exceed the magnitude
:of the wobble. Perhaps use of CCDs would reduce the errors. This is 
:something about which I have doubts, can anyone confirm the innacuracies
:present in photographic detection?

I have done research into this matter, and the 'wobble' is NOT detected
by photographs, but by radio signals.  I posted earlier on this topic
(in reply to the same person you did), and while my information was
correct, it was not complete and I appologize for that.

Here's how it works:

The stars that you can detect the 'wobble' in are neutron stars
(pulsars) that rotate many times every second (also known as millisecond
pulsars).  We receive these rotations as radio pulses, and can VERY
accurately time them.  The 'wobble' is when something causes the star to
come a little closer and then farther from the earth, causing different
time delays in the signal (sometimes as much as 10 milliseconds - a lot
for something as massive as a neutron star).  This suggests that
gravitational forces are acting on the star (sometimes pulling twards
the earth, and sometimes away).  The most logical conclusion is there is
an object (or objects) orbiting the star.  Canculations can be made to
estimate the mass of the objects orbiting the star.

In July of 91, two researches said they discovered such a pulsar that had
this 'wobble' effect.  Unfortunately, they failed to include the orbit
of the earth in their initial calculations, and when they did, the
planet 'dissapeared'.  However, since that time, other pulsars have been
discovered which do have the 'wobble' effect in a pattern too complex
for Earth's orbit to mimic (the researchers suggest 2-3 planets orbiting
one pulsar), and there are at lest two other pulsars that I read about
that have the 'wobble' effect as well.  The documents I read on this
matter suggest that with the possibility of planets existing in orbit of
such a violent environment as a pulsar, planets may be more common in
our galaxy than previously thought.  Note that there have been NO
optical searches that have revealed any hints of planets around other
stars.  Right now, pulsars are the only ones we can study (with Radio
Telescopes).

Sources (yes - actual sources. No false information. Look them up yourself). 

"Radio Pulses Hint at Unseen Planets"
Science News, Vol 141, Jan 11, 1992, page 20

"Planet dicovery retracted"
Science News, Vol ???, Jan 25, 1992, page 53

"The good companions"
Nature, Vol 355, Jan 9, 1992, page 111-112

"The planet vanishes"
Nature, Vol 355, Jan 16, 1992, page 187-188

"A planetary system around the millisecond pulsar PSR1257+12"
Nature, Vol 355, Jan 9, 1992, page 145 147

The last article gives very technical specs of the pulsar that is
believed to have planets around it (not an error).
 
:>There is also a good deal of other (indirect) evidence in the form of
:>spectrographic studies, which may be found in many introductory text-
:>books (at least in summary form).  I would direct you to these for 
:>further information.

:Spectroscopic detection allows much greater precision. So much that the
:motion of the earth must be subtracted in fact. One report of planetary
:detection was withdrawn as after suptracting the earths motion, the
:signal disappeared.

I already covered this.
 
:>One might raise the objection that these companions are too large to be
:>called planets.  If they are nonluminous and orbiting a star, I don't
:>know what else you'd call them.  

:So you would call a black hole or a neutron star a planet? The universe
:may be a bit young for black dwarfs, but these would also fit the bill.
:But cooler expired stars might not be detectable due to their small
:surface area.

If neutron stars were orbiting each other, it would be noticable.  These
bodies are not massive enough to be stars (less massive than Jupiter,
which is said to be a star that was not massive enough to form).  This
information is from the pulsar that is suspected to really have planets
(even with Earth's motion taken into account).

:A more salient point is that in this context, the importance of planets
:is that they may be home for extraterrestial life. If we restrict our
:search to planets of a size we know can support life, then the number
:drops to zero. I am not saying that gas giants cannot support life, but 
:that we do not -know- that gas giants can support life, excellent sci-fi
:by A Clark notwithstanding.

Mars can support life (alabeit simple, combon dioxide breathing).  NASA
officially lists life on Mars as 'inconclusive'.  I believe this is due
to a researcher who found bacteria living in antartica.

:>                                  In any case, their existence could
:>not possibly hurt the chances of smaller planets being present.  I
:>hope this is useful.

:Who knows? Honestly, how do you know. Suppose the sub-star inhabits the
:habitibal zone (where liquid water is possible). Would that not affect
:the possibility of life at that solar system?

	Thanks
	Robert Fentiman

UseNet: rfentima@ub.d.umn.edu
At: University of Minnesota, Duluth

Newsgroups: alt.alien.visitors