Exoplanet claim bites the dust

Exoplanet claim bites the dust : Nature News
"Strike one planet from the list of 400-odd found around stars in other
solar systems: a proposed planet near a star some 6 parsecs from Earth
may not exist after all.

The finding is also a strike against a planet-seeking strategy called
astrometry, which measures the side-to-side motion of a star on the sky
to see whether any unseen bodies might be orbiting it. Ground-based
astrometry has been used for more than a century, but none of the
extrasolar planets it has detected has been verified in subsequent studies."
http://www.nature.com/news/2009/0912...tml?s=news_rss

Dear Yousuf Khan:

On Dec 9, 12:39*am, Yousuf Khan wrote:
Exoplanet claim bites the dust : Nature News
"Strike one planet from the list of 400-odd found
around stars in other solar systems: a proposed
planet near a star some 6 parsecs from Earth
may not exist after all.

The finding is also a strike against a planet-
seeking strategy called astrometry, which
measures the side-to-side motion of a star on the
sky to see whether any unseen bodies might be
orbiting it. Ground-based astrometry has been
used for more than a century, but none of the
extrasolar planets it has detected has been
verified in subsequent studies.
"http://www.nature.com/news/2009/091208/full/462705a.html?s=news_rss

I wonder if this method actually detected mass-centers passing roughly
between us and those stars? Brown dwarfs and such. The method seems
good...

David A. Smith

On Dec 9, 8:16*am, dlzc wrote:
"http://www.nature.com/news/2009/091208/full/462705a.html?s=news_rss

I wonder if this method actually detected mass-centers passing roughly
between us and those stars? *Brown dwarfs and such. *The method seems
good...

David A. Smith

Well they did say that they think with more data, that the planet will
be detected eventually. It just can't be verified yet.

As for detecting mass centers in between, are you suggesting a lensing
event?

Yousuf Khan

Dear YKhan:

On Dec 9, 8:54*am, YKhan wrote:
On Dec 9, wrote:

"http://www.nature.com/news/2009/091208/full/462705a.html?s=news_rss

I wonder if this method actually detected mass-centers
passing roughly between us and those stars? *Brown
dwarfs and such. *The method seems good...

Well they did say that they think with more data, that
the planet will be detected eventually. It just can't be
verified yet.

As for detecting mass centers in between, are you
suggesting a lensing event?

Yes. If they did not detect a succession of "left" and "right"
positions, just a "before" and "maximum displacement", it could be a
lensing event. And it might also be lensing for something ostensibly
in orbit around Earth... with the proposed period.

Or so it seems to me.

David A. Smith

dlzc wrote:
Yes. If they did not detect a succession of "left" and "right"
positions, just a "before" and "maximum displacement", it could be a
lensing event. And it might also be lensing for something ostensibly
in orbit around Earth... with the proposed period.

Or so it seems to me.


What could be orbiting around Earth that is big enough to lens the star
yet not be seen on Earth?

Yousuf Khan

Dear Yousuf Khan:

On Dec 9, 3:41*pm, Yousuf Khan wrote:
dlzc wrote:
Yes. *If they did not detect a succession of "left"
and "right" positions, just a "before" and
"maximum displacement", it could be a lensing
event. *And it might also be lensing for something
ostensibly in orbit around Earth... with the
proposed period.

Or so it seems to me.

What could be orbiting around Earth that is big
enough to lens the star yet not be seen on Earth?

Vogons. Do you know where your towel is? (Sorry I could not resist.)

Well, Dark Matter is supposed to be able to do that... even though we
do not expect it to clump like this would have to.

David A. Smith

On Dec 10, 8:07*am, Dan Birchall
wrote:
It's pretty sad - astrometry was actually the first idea proposed for
detection of exoplanets, way back in 1855 by W.S. Jacob, but like the
quote above notes, it has _never_ successfully detected even a single
exoplanet that's then been verified with other methods. *

With improved equipment and techniques, Pravdo and Shaklan's STEPS
project looked promising (I read their preprint) but they need to get
verification using another method.

-Dan

Maybe it will work better when using a space telescope?

Yousuf Khan

In article ,
Yousuf Khan wrote:

Exoplanet claim bites the dust : Nature News
"Strike one planet from the list of 400-odd found around stars in other
solar systems: a proposed planet near a star some 6 parsecs from Earth
may not exist after all.

The finding is also a strike against a planet-seeking strategy called
astrometry, which measures the side-to-side motion of a star on the sky
to see whether any unseen bodies might be orbiting it. Ground-based
astrometry has been used for more than a century, but none of the
extrasolar planets it has detected has been verified in subsequent studies."
http://www.nature.com/news/2009/0912...tml?s=news_rss

Isn't it possible that the orbit is nearly face-on to us, such that the
wobble has a negligible radial component as seen from here? How much
varation in the Sun's radial velocity would be evident to an observer
some parsecs away and near one of the ecliptic poles?

--
Odysseus

Dear Odysseus

On Dec 10, 11:34*pm, Odysseus wrote:
....
Isn't it possible that the orbit is nearly face-on
to us, such that the wobble has a negligible radial
component as seen from here? How much
varation in the Sun's radial velocity would be evident
to an observer some parsecs away and near one of
the ecliptic poles?

The Sun orbits around the CoM of it and Jupiter. That point is, I
believe, outside the surface of the Sun:
http://en.wikipedia.org/wiki/Jupiter#Mass

So if you can resolve the Sun to more than one "pixel", you can infer
the presence of Jupiter.

David A. Smith

"Odysseus" wrote in message
news
In article ,
Yousuf Khan wrote:

Exoplanet claim bites the dust : Nature News
"Strike one planet from the list of 400-odd found around stars in other
solar systems: a proposed planet near a star some 6 parsecs from Earth
may not exist after all.

The finding is also a strike against a planet-seeking strategy called
astrometry, which measures the side-to-side motion of a star on the sky
to see whether any unseen bodies might be orbiting it. Ground-based
astrometry has been used for more than a century, but none of the
extrasolar planets it has detected has been verified in subsequent
studies."
http://www.nature.com/news/2009/0912...tml?s=news_rss

Isn't it possible that the orbit is nearly face-on to us, such that the
wobble has a negligible radial component as seen from here? How much
varation in the Sun's radial velocity would be evident to an observer
some parsecs away and near one of the ecliptic poles?


Celestial bodies orbit a common barycentre.
http://www.androcles01.pwp.blueyonde...AlgolOrbit.gif
The Sun + Jupiter means you'll see the Sun make a small circle
against the backdrop of stars, but it will take 12 years to do so.
Thus finding planets is time consuming. Finding Mercury will take
88 days if you could see the even tinier circle of the Sun.