Kapteyn's Star - Ancient two-planet system with one planet in the HZ

View previous topic View next topic Go down

Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Sirius_Alpha on 3rd June 2014, 7:39 pm

Two planets orbit nearby ancient star
http://phys.org/news/2014-06-astronomers-ancient-worlds-galaxy-door.html

Surprised it was made public this soon.

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

Number of posts : 3468
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Sirius_Alpha on 3rd June 2014, 8:22 pm

Two planets around Kapteyn's star : a cold and a temperate super-Earth orbiting the nearest halo red-dwarf
http://arxiv.org/abs/1406.0818

Exoplanets of a few Earth masses can be now detected around nearby low-mass stars using Doppler spectroscopy. In this paper, we investigate the radial velocity variations of Kapteyn's star, which is both a sub-dwarf M-star and the nearest halo object to the Sun. The observations comprise archival and new HARPS, HIRES and PFS Doppler measurements. Two Doppler signals are detected at periods of 48 and 120 days using likelihood periodograms and a Bayesian analysis of the data. Using the same techniques, the activity indicies and archival ASAS-3 photometry show evidence for low-level activity periodicities of the order of several hundred days. However, there are no significant correlations with the radial velocity variations on the same time-scales. The inclusion of planetary Keplerian signals in the model results in levels of correlated and excess white noise that are remarkably low compared to younger G, K and M dwarfs. We conclude that Kapteyn's star is most probably orbited by two super-Earth mass planets, one of which is orbiting in its circumstellar habitable zone, becoming the oldest potentially habitable planet known to date. The presence and long-term survival of a planetary system seems a remarkable feat given the peculiar origin and kinematic history of Kapteyn's star. The detection of super-Earth mass planets around halo stars provides important insights into planet-formation processes in the early days of the Milky Way.

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

Number of posts : 3468
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Led_Zep on 3rd June 2014, 9:37 pm

We have a Kepler-186f at only 13 light years !! Great !
avatar
Led_Zep
Jovian
Jovian

Number of posts : 517
Location : France
Registration date : 2011-09-09

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Sirius_Alpha on 3rd June 2014, 9:42 pm

Kepler-186f is probably not a mini-Neptune/gas dwarf, as the minimum-mass of Kapteyn's Star b would seem to imply.

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

Number of posts : 3468
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Shellface on 3rd June 2014, 9:55 pm

I… yeah. Wow. I'm… impressed. Not sure how else to put it.

Nice to see they have more reasonable parameter errors this time. Was getting concerned.

I suppose we get to look at an inaccurate depiction of the system tomorrow?

Shellface
Neptune-Mass
Neptune-Mass

Number of posts : 282
Location : g2 17.∞ 997 t
Registration date : 2013-02-14

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Sunchaser on 3rd June 2014, 11:49 pm

Complete with green continents!


How's this?
http://phl.upr.edu/press-releases/kapteyn
-M-
avatar
Sunchaser
Planetesimal
Planetesimal

Number of posts : 133
Age : 46
Registration date : 2011-12-23

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Lazarus on 4th June 2014, 1:42 am

Old, metal-poor, extragalactic origin... nice to have something fill the gap since HIP 13044b got disproven.
avatar
Lazarus
dG star
dG star

Number of posts : 2819
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Edasich on 4th June 2014, 3:28 am

Now there are Barnars and Luyten's star left to have exoplanets detected (or confirmed).  What a Face 
avatar
Edasich
dM star
dM star

Number of posts : 1510
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by tommi59 on 4th June 2014, 6:21 am

Any probability for transit for planet b?
avatar
tommi59
Jovian
Jovian

Number of posts : 546
Age : 39
Location : Baile Atha Cliath
Registration date : 2010-07-31

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Daniel on 4th June 2014, 12:05 pm

Sirius_Alpha wrote:Kepler-186f is probably not a mini-Neptune/gas dwarf, as the minimum-mass of Kapteyn's Star b would seem to imply.

After the Kepler-10c a giant super-earth also found around an old star like this article say,I wouldn't be surprise that  Kapteyn b & c can be a super-earth instead of a gas dwarf,without the size we can't know for sure.  

Kepler-10c boosts case for life on other worlds

http://www.smh.com.au/technology/sci-tech/astronomy/kepler10c-boosts-case-for-life-on-other-worlds-20140603-zrwdx.html
avatar
Daniel
SuperEarth
SuperEarth

Number of posts : 238
Registration date : 2009-11-14

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Sirius_Alpha on 4th June 2014, 2:06 pm

I don't know how appropriate it is to cherry-pick planets for which to set expectations. While I definitely admit Kapteyn's Star b could be rocky, it is still true that the overwhelming majority of planets with masses similar to the minimum mass of Kapteyn's Star b are low-density planets.

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

Number of posts : 3468
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Lazarus on 7th June 2014, 9:32 am

The optimistic scenario is that the planet is not habitable and never was.

If the universe was building habitable planets at 11 Ga, it makes it more likely that the reason for the Great Silence is likely to be something that is located in our future, e.g. that technological civilisations have short lifetimes and don't last long enough to engage in interstellar travel.
avatar
Lazarus
dG star
dG star

Number of posts : 2819
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Daniel on 7th June 2014, 10:48 am

Lazarus wrote:The optimistic scenario is that the planet is not habitable and never was.

If the universe was building habitable planets at 11 Ga, it makes it more likely that the reason for the Great Silence is likely to be something that is located in our future, e.g. that technological civilisations have short lifetimes and don't last long enough to engage in interstellar travel.

This can be consider only one of many hypotheses for why of the Great Silence (Fermi Paradox),could be civilizations that are so old that we could not ever detect them because they are too sophisticate to we understand them,we just don't know...
avatar
Daniel
SuperEarth
SuperEarth

Number of posts : 238
Registration date : 2009-11-14

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by PlutonianEmpire on 7th June 2014, 2:10 pm

I noticed that they used the visible earth cloud map to use as the dark spots on the planet in the press release. Razz

_________________
Circumbinary sunset! I love you
avatar
PlutonianEmpire
Planetesimal
Planetesimal

Number of posts : 136
Age : 32
Location : Minnesota
Registration date : 2012-01-29

View user profile http://www.plutonianempire.net/

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Led_Zep on 12th May 2015, 9:21 pm

Kapteyn b : another fake ?

http://arxiv.org/abs/1505.02778

Stellar activity mimics a habitable-zone planet around Kapteyn's star

Kapteyn's star is an old M subdwarf believed to be a member of the Galactic halo population of stars. A recent study has claimed the existence of two super earth planets around the star based on radial velocity (RV) observations. The innermost of these candidate planets--Kapteyn b (P = 48 days)--resides within the circumstellar habitable zone. Given recent progress in understanding the impact of stellar activity in detecting planetary signals, we have analyzed the observed HARPS data for signatures of stellar activity. We find that while Kapteyn's star is photometrically very stable, a suite of spectral activity indices reveals a large-amplitude rotation signal, and we determine the stellar rotation period to be 143 days. The spectral activity tracers are strongly correlated with the purported RV signal of "planet b," and the 48-day period is an integer fraction (1/3) of the stellar rotation period. We conclude that Kapteyn b is not a planet in the Habitable Zone, but an artifact of stellar activity.
avatar
Led_Zep
Jovian
Jovian

Number of posts : 517
Location : France
Registration date : 2011-09-09

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Lazarus on 13th May 2015, 2:01 am

Ouch. Looks more and more like this kind of analysis should be done before making announcements about planets. (Interesting that these activity artifacts seem to occur mainly at periods that would correspond to planets near the HZ, I guess this is an unfortunate consequence of typical M-dwarf rotation periods?)
avatar
Lazarus
dG star
dG star

Number of posts : 2819
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Daniel on 13th May 2015, 7:40 am

I consider this a good news,more space for truly earth mass/size exoplanet in the habitable zone of this star that soon can be detected with the next generation of instruments and telescopes like the E-ELT or the EXPRESSO high precision radial velocity of VLT among other numerous other instruments that been in development or in test phase.
avatar
Daniel
SuperEarth
SuperEarth

Number of posts : 238
Registration date : 2009-11-14

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Lazarus on 13th June 2015, 9:52 am

Lazarus wrote:Old, metal-poor, extragalactic origin... nice to have something fill the gap since HIP 13044b got disproven.
Or maybe not extragalactic after all?

Navarette et al. (2015) "The Kapteyn moving group is not tidal debris from ω Centauri"
http://arxiv.org/abs/1506.02041
avatar
Lazarus
dG star
dG star

Number of posts : 2819
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Led_Zep on 30th June 2015, 9:05 pm

Fight !! Shocked

http://arxiv.org/abs/1506.09072

No evidence for activity correlations in the radial velocities of Kapteyn's star

Stellar activity may induce Doppler variability at the level of a few m/s which can then be confused by the Doppler signal of an exoplanet orbiting the star. To first order, linear correlations between radial velocity measurements and activity indices have been proposed to account for any such correlation. The likely presence of two super-Earths orbiting Kapteyn's star was reported in Anglada et al. (2014, MNRAS 443L, 89A), but this claim was recently challenged by Robertson et al. (2015, ApJ 805L, 22R) arguing evidence of a rotation period (143 days) at three times the orbital period of one of the proposed planets (Kapteyn's b, P=48.6 days), and the existence of strong linear correlations between its Doppler signal and activity data. By re-analyzing the data using global optimization methods and model comparison, we show that such claim is incorrect given that; 1) the choice of a rotation period at 143 days is unjustified, and 2) the presence of linear correlations is not supported by the data. We conclude that the radial velocity signals of Kapteyn's star remain more simply explained by the presence of two super-Earth candidates orbiting it. We also advocate for the use of global optimization procedures and objective arguments, instead of claims lacking of a minimal statistical support.
avatar
Led_Zep
Jovian
Jovian

Number of posts : 517
Location : France
Registration date : 2011-09-09

View user profile

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

Post by Sirius_Alpha on 1st July 2015, 4:21 pm

That seems rather caustic Neutral

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

Number of posts : 3468
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Kapteyn's Star - Ancient two-planet system with one planet in the HZ

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