Amateur Finds

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Amateur Finds

Post by Edasich on 21st October 2009, 5:23 am

Premiss: the things I'm going to type here SHOULD NOT break any embargo breach since paper has been published and submitted at ArXiv.org too. Moreover they also should not have a scientific significance since based on few data available and most of results come from approximations. Nevertheless what's come out sounds interesting.

Do you remember the paper A Dedicated M Dwarf Planet Search Using The Hobby-Eberly Telescope?

The paper talks about detection efficiency of low mass exoplanets around nearby red dwarfs. Even a more recent one from UVES talks about the same but observing another stock of nearby M dwarfs.

However radial velocity sets are not available in written form, but in graphical one. Employing bitmap, wordpad and a bit of patience, I've extracted vels and sys files for related stellar objects and I've performed a Systemic Console search for planets.
Results are interesting.
Most of the stars show clear signals of short-period bodies in tight orbits and few ones even hints of additional longer period companions.

Among these I notice the very nearby star GJ 687 (or BD+68 946) once suspected to host a massive substellar object in wide and eccentric orbit (>10 Mj e<0.9). Well, the best fit consist in a close-in hot earth and a "low-mass" brown dwarf (or massive superplanet) at 6.17 AUs and e=0.8.

Between survey stars there is Barnard's Star too and, obviously that is the trickiest object. I don't report anything, since neither from HET or UVES paper I've found a convincing fit.

However, briefly I've summarized observed results (Chi Square<<0.1) in graphical form to not type a "fathoms-long" topic.
I have put Sun and Mercury's mutual distances to compare with M-dwarf/planetary objects ones.
Enjoy:





Some planets show relatively mild eccentricity and few others high ones, but most of the objects lies in circular orbit.

Among most interesting cases I underline those of GJ 272 and GJ 671. The former shows two super-earths in close orbits and the latter a low-mass hot Neptune and a GJ 876 c-like dwarf-jovian within system's habitable zone.

Feedback is welcome.
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Re: Amateur Finds

Post by Sirius_Alpha on 21st October 2009, 2:09 pm

When fitting these planets in Systemic, what kind of values did you get for the F-test?

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Re: Amateur Finds

Post by Edasich on 21st October 2009, 4:16 pm

Gives me chi-square close to 0 and jitter = NaN
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Re: Amateur Finds

Post by Lazarus on 21st October 2009, 4:19 pm

One of the things to watch out for is effect of rotation, which may mimic a planet.
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Re: Amateur Finds

Post by Edasich on 21st October 2009, 4:21 pm

Even activity must be accounted. I say this little research of mine has few scientific feasibility, but it's a nice speculative work.

However the GJ 687's case is interesting, since seems to not rule out the long period superplanet in eccentric orbit and hints the presence of a super-earth too.
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Re: Amateur Finds

Post by Sirius_Alpha on 21st October 2009, 9:13 pm

Edasich wrote:Gives me chi-square close to 0 and jitter = NaN
What about F-test?

Edit: After looking at the data plots in the paper you referenced, I can certainly see how you got your planets. With so few points though, it doesn't look too robust, like you said. Don't forget your fits! Maybe you can compare them later to future detections of planets around these stars.

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Re: Amateur Finds

Post by Sedna on 25th October 2009, 10:44 am

Edasich wrote:Among most interesting cases I underline those of GJ 272 and GJ 671. The former shows two super-earths in close orbits and the latter a low-mass hot Neptune and a GJ 876 c-like dwarf-jovian within system's habitable zone.

Hey Edasich,

What are your parameters for this star ? Because after my calculations, GJ 671 c does not lie in the HZ. Or am I wrong ?

Bye

Sedna

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Re: Amateur Finds

Post by Edasich on 25th October 2009, 10:59 am

Sedna wrote:
Edasich wrote:Among most interesting cases I underline those of GJ 272 and GJ 671. The former shows two super-earths in close orbits and the latter a low-mass hot Neptune and a GJ 876 c-like dwarf-jovian within system's habitable zone.

Hey Edasich,

What are your parameters for this star ? Because after my calculations, GJ 671 c does not lie in the HZ. Or am I wrong ?

Bye

Sedna

As I've said in another thread, I have used parameters from NsTed database

http://nsted.ipac.caltech.edu/
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Re: Amateur Finds

Post by Sedna on 27th October 2009, 5:57 am

Oh, excuse me, I didn't read the other thread. I used NstED too; so why a difference with the same data ?

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