Are there any news about Lalande 21185?

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Are there any news about Lalande 21185?

Post by Bruno on 7th May 2010, 9:39 pm

Hello,
I'm Bruno Alessi and this is my first post here.
You have a really cool forum - I hope to contribute even if by a very little amount!
Right now, I am wondering what happened to Lalande 21185 and it's
supposed planet (or planets). I know that HST and ground based
observations ruled out the planets that past observers (like
Van de Kamp) claimed to exist around the Barnard star and 61 Cygni.
But to my knowledge nothing was published about Lalande 21185 (besides
what Gatewood has wrote about this star).
So, it seems that there are no independent verification using radial
velocities (or better astrometry... or imaging...) available to confirm
or to rule out planets having the characteristics Gatewood (or Lippincott,
if I recall correctly) determined using astrometry.
Although I know very little of the math and physics involved in the
art of the (exo)planetary science, it seems that with the technology
the top researchers have at their disposal, it would be easy to check
Lal 21185 using RVs to a level of few m.s-1 and jovian planets around
low mass stars would produce a noticeable wobble much larger that the
one meter per second achieved by HARPS, also lal 21185 is nearby and bright.
So...?
May be this discussion is not new here. If this is the case, please excuse me
for not using the search tool adequately!
Bruno

P.S. it is better to be a humble Hydrogen atom than to be a short-lived
neutral neutron, don't you think so?

Bruno
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Re: Are there any news about Lalande 21185?

Post by Sirius_Alpha on 7th May 2010, 10:17 pm

Welcome! Glad to have you Very Happy

Everything you know about Lalande 21185, as far as I'm aware, is up to date. There is no current evidence for the presence of any planets orbiting the star. If I'm not mistaken, Lalande 21185 is an active star. This may pose a problem for high-precision radial velocity studies.

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Re: Are there any news about Lalande 21185?

Post by Borislav on 8th May 2010, 8:08 am

Bruno wrote:Lal 21185 using RVs to a level of few m.s-1 and jovian planets around
low mass stars would produce a noticeable wobble much larger that the
one meter per second achieved by HARPS, also lal 21185 is nearby and bright.
So...?
May be this discussion is not new here. If this is the case, please excuse me
for not using the search tool adequately!
Bruno

P.S. it is better to be a humble Hydrogen atom than to be a short-lived
neutral neutron, don't you think so?

For ESO star too northern.

Star of active monitors Geneva and California groups since 1995. In total on ELODIE, SOPHIE and Keck-HIRES spectrografs received more than 130 high-resolution spectra.

Borislav
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Re: Are there any news about Lalande 21185?

Post by Bruno on 8th May 2010, 9:14 am

Thanks for commenting here.

Yes, too northern for ESO!

and I forgot the most obvious source of information

http://en.wikipedia.org/wiki/Lalande_21185d

There you can read:

"...Gatewood claimed that such companions would usually appear more than 0.8 arc second from the M dwarf itself. However a paper by Gatewood published only a few years earlier[19] and subsequent searches by others, using coronagraphs and multifilter techniques to reduce the scattered-light problems from the star, have yet to positively identify any such companions[20] and so his claim remains unconfirmed and is now in doubt...."

"...
This star's measured radial velocity is so constant that astronomer and planet hunter Geoff Marcy uses it as a perfect example of "normal" M dwarf stability levels.[21] The negative results of this and other surveys do not preclude the presence of a planetary system entirely but they do set a upper boundary on the mass of any planets that might be present. The detection limit by current technology for this star system is a little less than the mass of the planet Jupiter. New Earth and space based instruments will certainty lower this limit further and possibly detect any small planets that may be present...."

Bruno
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