New Alpha Centauri planets quest, thanks to TPS ! Options

[ngunn]

it's intriguing to consider whether there is a negative relationship, that inner planets are a sign that planets will not be found at longer periods (~50-500d).

I've just looked through the known multiple planet systems (3+planets) and way over half of them have planets with both under 20d and over 50d periods. It's anecdotal, I suppose, but my impression is that the correlation is positive.

[Reed]

In the paper, they state that they have enough data to detect a 4 Earth-mass planet in the habitable zone of Alf Cen B if it were there.

I don't think this is quite what they said. I assume you are referring to:

However, the observed radial-velocity semi-amplitude is equivalent to the one induced by a four Earth minimum mass planet in the habitable zone of the star (P = 200 days). The HARPS spectrograph has therefore the precision to detect a new category of planets: Habitable super-Earths.

The way I read that, they are only saying HARPS has the sensitivity to detect such a planet. The current detection is based on observing many orbits to identify a periodic signal, and for a habitable zone (200 day) planet they would have far fewer.

[Bill]

I don't know if this is the right thread, but it seems that nobody talked about this future mission selected by ESA which could study Alpha Centauri, among other things.

CHEOPS on ESA website
Cheops Website

[K-P]

It seems we have even more interesting planet system available in our "galactic neighborhood" now.

Science team led by Finnish astronomer Mikko Tuomi found 5 (!) planets around Tau Ceti.

It's getting crowded in this corner of our spiral arm...

http://www.space.com/18967-nearby-habitabl...t-tau-ceti.html

[ngunn]

Link to the paper (from BBC News): http://star-www.herts.ac.uk/~hraj/tauceti/paper.pdf
Orbital data are on page 16.

[0101Morpheus]

I've heard about this system last night while lurking on another forum. It's more hard line than this forum though, so I recommend if you want to make an account there you should have a general knowledge about exoplanet mechanics.

http://solar-flux.forumandco.com/

Now I am going to be the skeptic here. While I am not surprised that Tau Ceti could have planets, the inclination of the system is very unknown. Previous studies have given inclinations ranging from near edge on to face on. Now the star is known to have a dust disk and that would normally constrain things, given that low mass systems tend to be coplanar, but there are just as many models of the inclination of the disk as there are the star!

http://adsabs.harvard.edu/abs/2004MNRAS.351L..54G

The RV method only gives minimum masses, if there is a high inclination then these are neptune sized worlds, not super-earths. There are to many to many assumptions right now, and the team used the assumptions that favored their model. There is a better case for Alpha Centauri Bb then these planets found by an experimental method that has yet to be verified.

If I were in charge a followup, I would look for planet b and work my way up. HARPS is in the best position to do this since Tau Ceti is visible in both the North and Southern hemisphere.

[TheAnt]

A bit late perhaps but I happened upon what I think is the original press release for the Tau Ceti system findings.
Nothing new not covered in the other sources you others already have linked though.

University of Hertfordshire news page

The study is part of the European RoPACS program where the same University of Hertfordshire are coordinating the work.