Nu Ophiuchi and Tau Geminorum b as planets?

View previous topic View next topic Go down

Nu Ophiuchi and Tau Geminorum b as planets?

Post by Edasich on 3rd January 2011, 8:22 am

avatar
Edasich
dM star
dM star

Number of posts : 1516
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Sirius_Alpha on 3rd January 2011, 11:45 am

That's odd. I would have considered them brown dwarfs.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3493
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Edasich on 3rd January 2011, 1:30 pm

It seems the planetary domain is being stretched up to 20-25 Jupiter masses according to Sahlmann et al. (2010).
avatar
Edasich
dM star
dM star

Number of posts : 1516
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Sirius_Alpha on 3rd January 2011, 1:48 pm

I guess that means we get Alcor b as a planet. That's kinda cool.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3493
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Lazarus on 3rd January 2011, 5:54 pm

Going by what was updated today it looks like four objects have been confirmed at the Planets Beyond the Main Sequence conference, the other two being 91 Aquarii b and HD 59686 b, which were all announced at a previous conference back in 2004 but still have no discovery paper yet.

As for the inclusion cutoff for EPE, the readme states that the cutoff being used is 20 Jupiter masses to 2 sigma. Not entirely sure what they are using in the case where error bars are not available.
avatar
Lazarus
dG star
dG star

Number of posts : 2843
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Sirius_Alpha on 3rd January 2011, 6:11 pm

Both 91 Aqr b and HD 59686 b were confirmed before the EPE updated.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3493
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Lazarus on 3rd January 2011, 6:18 pm

True, but they both now have a note from 3-Jan-2011 to the effect that they are now confirmed.

In fact that was fairly inconsistent to have two of them treated as confirmed and two as unconfirmed, though I guess the 91 Aqr and HD 59686 systems had more follow-up papers?
avatar
Lazarus
dG star
dG star

Number of posts : 2843
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Edasich on 4th January 2011, 5:26 am

Sirius_Alpha wrote:I guess that means we get Alcor b as a planet. That's kinda cool.

Alcor b?? Or Alioth b (epsilon UMa)?
avatar
Edasich
dM star
dM star

Number of posts : 1516
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Sirius_Alpha on 4th January 2011, 12:13 pm

Yeah, Alioth b, my mistake.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3493
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Edasich on 4th January 2011, 1:51 pm

Indeed I don't understand why it is not listed in EPE.
avatar
Edasich
dM star
dM star

Number of posts : 1516
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Sirius_Alpha on 4th January 2011, 9:19 pm

Planets around Giant Stars
http://arxiv.org/abs/1101.0615

We present results from a radial-velocity survey of 373 giant stars at Lick Observatory, which started in 1999. The previously announced planets iota Dra b and Pollux b are confirmed by continued monitoring. The frequency of detected planetary companions appears to increase with metallicity. The star nu Oph is orbited by two brown dwarf companions with masses of 22.3 M_Jup and 24.5 M_Jup in orbits with a period ratio close to 6:1. It is likely that the two companions to nu Oph formed in a disk around the star.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3493
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Lazarus on 5th January 2011, 4:56 am

Nice. More evidence against the usefulness of the 13 Jupiter mass cutoff.
avatar
Lazarus
dG star
dG star

Number of posts : 2843
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Lazarus on 16th April 2011, 10:57 am

An Affine-Invariant Sampler for Exoplanet Fitting and Discovery in Radial Velocity Data

Contains a more complete set of orbital elements for Nu Ophiuchi (=HIP 88048), and also a 2-companion model for HD 59686 (=HIP 36616), which apparently has a stellar companion in a ~33 year orbit in addition to the giant planet.
avatar
Lazarus
dG star
dG star

Number of posts : 2843
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Edasich on 16th April 2011, 1:06 pm

Uhm, nice find about these few rated giant star-exoplanet systems Smile
avatar
Edasich
dM star
dM star

Number of posts : 1516
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Sirius_Alpha on 16th April 2011, 11:41 pm

Lazarus wrote:HD 59686 ... which apparently has a stellar companion in a ~33 year orbit in addition to the giant planet.
Where are you seeing that? I haven't managed to find reference to that in the paper yet (though I'm guessing it's right in front of my face...).

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3493
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Lazarus on 17th April 2011, 9:07 am

Sirius_Alpha wrote:Where are you seeing that? I haven't managed to find reference to that in the paper yet (though I'm guessing it's right in front of my face...).
Taking the orbital elements in table 2 and converting them to the usual ones that are more familiar, using a stellar mass of 1.5 times solar (ignoring errors on stellar mass):

InnerOuter
Period (d)298.78 0.3712000 410
Minimum mass (mJ)5.78 0.14657.5 7.4
Semimajor axis (AU)1.0025 0.000813.2 0.3
Assuming my calculation for the secondary mass from the mass function is correct, the outer companion has a minimum mass of around 0.63 solar masses...
avatar
Lazarus
dG star
dG star

Number of posts : 2843
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Lazarus on 17th April 2011, 1:49 pm

For reference the equivalent parameters for Nu Ophiuchi are as follows, for a stellar mass of 2.7 solar masses (again neglecting uncertainty in stellar mass):

InnerOuter
Period (d)529.93 0.213211 35
Minimum mass (mJ)22.295 0.09724.73 0.24
Semimajor axis (AU)1.7893 0.00055.95 0.04
avatar
Lazarus
dG star
dG star

Number of posts : 2843
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Nu Ophiuchi and Tau Geminorum b as planets?

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum