There are reports from Torino about HARPS observations of Gliese 581(g)
Vogt et al reported on additional possible planets in the multi-planet low mass Gliese 581(g) system.
In particular they showed a ~ 3 sigma detection of a possible 3+ earth mass planet in a circular orbit with an orbital period consistent with a temperate surface.
The paper used a combination of historic Keck data, published HARPS data up through 2008 and new high cadence Keck data.
There was some concern when the paper came out that the False Alarm Probability was underestimated (see Cumming et al for discussion of False Alarm Probability estimates and general considerations ).
The two new planets reported by Vogt et al, were both coming in close to the detection threshold and there have been problems disentangllng closely packed multi-planet systems, due to aliasing and harmonic contamination. Gliese 581, in particular, has had a couple of claims about its planets backed out before.
What everyone in the community was waiting for is what the HARPS group could say, since they ought to have a couple of years more data, presumably with high cadence also, and very high velocity precision.
IAU 276 The Astrophysics of Planetary Systems: Formation, Structure, and Dynamical Evolution just got underway in Torino, Italy (good week to be in Italy – meeting in Sardinia also, Wish I Was There).
Ray Jay reports on social networks:
” ”We cannot confirm it [Gliese 581g] in our HARPS data” – Francesco Pepe (Geneva team) at IAU 276 in Torino.”
This is interesting, but not totally surprising.
It will be very interesting to see the HARPS paper, and how this shakes out.
Gliese 581g could still be there, it could be in the orbit reported, but this needs some more work.
PS: additional oral reports from the meeting.
HARPS statement is stronger than “we don’t see it” – they find that if they force a solution they get a negative signal appearing, implying the planet is not there, not just that they are not sensitive to it.
50% more data since 2008 published series.
This could get interesting.