Still working on an
30 new planets reported at "Towards Other Earths" Porto conference.
Some of them are rather interesting.
The Extrasolar Planet Encyclopaedia reported 30 new planets reported by 7 different teams at the Towards Other Earths conference in Porto - wish I could have been there, too many meetings going on, too little time.
This is going to be the trend for a while - most planet discoveries will be announced in batches, unless there is something startling, unexpected or record breaking found.
With about 400 extrasolar planets now known, finding just one is not news, unless it is different.
One of the nice things about this batch is the appearance of some more "real Jupiters" - planets with masses of about a jupiter mass, and orbital periods of many years - over 10 years in a couple of cases. Some are in multi-planet systems. And some may have reasonably low orbital eccentricities.
So, normal, almost Solar System like configurations.
Not the first, JJ got the first as I recall, but building up statistics is important.
What caught my eye though, is that Santos has three long period Jovians, with parent stars whose metallicity is significantly sub-solar.
There is a well known planet-metallicity correlation, with the probability o an planet being observed about a roughly solar mass star being proportional to about Z2, for metallicitiies close to or higher than solar.
For short orbital period planets
I've long argued on speculative theoretical grounds that there was an observational selection effect, and that some of the correlation was orbital period biased - that we ought to see proportionately more long period jovian planets in lower metallicity systems as we got more data on low metallicity stars with longer baselines (for obvious reasons the stars monitored frequently and precisely at the beginning of surveys were biased towards solar like stars, including near solar metallicity).
It is too early to tell for sure, but the Santos group noted some time ago that the Z correlation seemed to flatten at sub-solar metallicity, and the 3 new planets ought to strengthen that trend. How big the effect is depends on how large the monitored sample is and the completeness to date - if they were looking at very many low Z stars for all this time, then the result is less significant. We'll see when the paper comes out.
Anyway, I'm reassured by the reports of the Santos detections - I like to have my theoretical prejudices occasionally confirmed.
Now to understand what is going on...
Physical Science
Comments
On the other hand this is also consistent with the metallicity of the short period hosts being boosted by pollution by the planets. Remember seeing something about the metallicity effect being seen in main sequence stars but not in the more convective evolved stars which follows along the same lines.
Or is that in fact your speculative theoretical argument? The description above leaves enough to the imagination that it could be.
Posted by: Arunav | October 23, 2009 12:45 PM
Are there any long-term projects aimed at detecting planets in open clusters? Various surveys for hot Jupiters keep coming up with nothing, maybe these environments favour longer-period planets too.
Posted by: andy | October 23, 2009 3:45 PM
@Arunav - we looked at the pollution issue, and it doesn't seem to work out in detail, although if "Last of the Mohican" scenarios for planet formation/migration are correct it would be an issue
@andy - several long term projects looking at nearby open clusters.
I'm strongly inclined to conjecture that disk truncation in dense environment inhibit migration - that the "hot Jupiters" are generally from isolated or low density star forming regions, and that "solar system like" systems are from denser richer star forming associations where radiative and/or dynamic truncation of disks inhibited type II migration.
Not at all a settled question though, but I am glad to see some long period jovians in sub-solar metallicity systems
Posted by: Steinn Sigurdsson | October 23, 2009 3:50 PM
Although there are a variety of star masses, the 1st Solar System Displacement of a Jupiter-like mass is common. In some cases, the Jupiter-like mass is large enough to form a minor star. In other cases, the star itself will separate into two or more stars before its 1st Solar System Displacement.
The basic template of polarized First Space is used is all cases of initial mass displacement. However, the mass-unit value of each star system is a variable - i.e., the Earth is not the unit value of every star system.
Posted by: Frank Hatch | October 24, 2009 11:07 PM
Well that's good to know that searches for longer-period planets are going on for open clusters. If solar-system type configurations are more common in such dense environments, that makes M67 look like a very interesting place for planets. Maybe also Terzan 5... come on, B1620-26 cannot be the only planetary system in a globular cluster.
Posted by: andy | October 25, 2009 5:37 PM
Things I learned in school science lessons: 1) there are no known extrasolar planets. 2) neurons are not created during adult life. 3) coal was the fuel of the future.
Posted by: Alex | October 27, 2009 6:02 AM
@Andy - you are correct, 1620-26 cannot be the only planetary system in a globular cluster. .. ;-)
Ter 5 is hard - very high dispersion.
@Alex - 2 out of 3 ain't bad. So far. Can't burn coal for much longer, something will give one way or another.
Posted by: Steinn Sigurdsson | October 27, 2009 5:06 PM
You have to forgive Bradford Local Education Authority for missing neurogenesis; Elizabeth Gould had only just started redesigning the monkey house then.
Coal? Well...we still learned about how great the new Selby coalfield was and how Yorkshire would power the British economy for the next 200 years. This rang a tad hollow after the big shutdown in 1990.
Posted by: Alex | October 28, 2009 4:35 AM