Steinn Sigurðsson (Pennsylvania State) has been reporting from the Greek island of Santorini, where he is attending the Extreme Solar Systems conference. I want to send you at once to Steinn’s Dynamics of Cats weblog, where updates are being filed and will presumably continue through today, the conference’s last day. It sounds like a terrific gathering filled with the energizing news of discoveries, its theme being, in addition to finding Earth-like planets, the study of exoplanets in tricky places like dense star clusters, near giant stars and orbiting pulsars.
That last is fitting enough, given that the first extrasolar planets of Earth-like mass were discovered 15 years ago around the pulsar PSR 1257+12; in fact, the conference meets on the occasion of that anniversary and celebrates as well the sixtieth birthday of Alex Wolszczan, the discoverer of those worlds. All of that and beauteous Santorini too, though as Steinn reports, the heat has been the worst since 1916, as per locals who should know.
Steinn has to honor embargos and there are things he can’t speak about, but among the more interesting things to emerge is that the California-Carnegie team has found a true Jupiter analogue around a G8V main sequence dwarf, orbiting at about 4.4 AU. From Steinn’s notes:
This is a Jupiter – a cold gaseous giant planet in the right place, which does not look to have migrated or done anything messy. It is of course a fabulous target for low mass rocky planets interior to the current known giant, including in the habitable zone. It is also a very promising indicator that the large number of known “trending” systems being monitored will resolve out to be solar system analogs – maybe 20-30% of stars being monitored may be solar system like if this all pans out – but that is speculative at this stage.
Some other intriguing notes:
- Nine nearby white dwarfs are now known to have confirmed warm debris disks;
- Planets around giant stars seem to be proliferating. The California-Carnegie team has reported three confirmed Jovian planets and four other candidates; the East-Asian Planet Search Network (EAPSNET) likewise has a detection around a K giant in an open cluster and several candidates; and the Pennsylvania State-Poland search team also announces several detections with a whopping thirty candidates.
- A number of low-mass planet candidates are emerging around K and M stars, but no formal announcements as yet. Take note of Steinn’s provocative comment: “I don’t think the “Rare Earth” hypothesis is holding up well, the pieces of the argument are being dismantled wholesale as we find more systems and gain more understanding.”
And this should interest those interested in the nearest stars, quoting Steinn again:
There is now data on Barnard’s star and Proxima Cen with good velocity sensitivity (~ 3 m/sec). Barnard’s star (old nearby M dwarf) is active and velocity variability correlates with photometric variability – Proxima Cen is very variable, but the fluctuations in velocity do not correlate with the fluctuations in brightness. Maybe something there if the data can be dug into. Should have better than 1 m/sec observations with UVES spectrograph on the VLT telescope. This will get to sensitivity of one earth mass in the “habitable zone” (which isn’t really, the star is variable). Maybe there is a low mass planet in moderately short period orbit around Proxima Cen – be interesting if that turnsout to be the case.
I don’t want to go any further here (we’ll be discussing many of these findings here in days to come), but I do urge you to read through Steinn’s postings as Santorini winds down. There is much of interest — the Swiss group alone has twelve new planets — and the chance to follow a conference from afar at this level of detail is most welcome. A glance at photos of Santorini from the conference site as well as Steinn’s own snapshots has me thinking about how to get there myself one day soon.