Then i would say a body has to be dense enough and hot enough for it to fuse, but that's my own opinion about a definition But yes, it's not really science anyway, but more just about word juggling - aka. end of discussion, ok?

Two more exoplanets to go and we're even with last year. And in that case we've gotten both quantity as well as quality improvements of exoplanets.

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It looks like the flood gates are open. A probable giant planet imaged in the Beta Pictoris disk -- this one's ~8M_J and only 8AU from Beta Pictoris. Direct Imaging and Spectroscopy of a Planetary Mass Candidate Companion to a Young Solar Analog claims to have imaged a ~8M_J object 330AU from 1RXS J160929.1-210524 (that'll never fly in the media). Meanwhile Ralph Neuhaeuser keeps studying the object near GQ Lup he imaged in 2005. Unfortunately the best estimate for its mass is now 30M_J, so his earlier claim of having imaged an exoplanet probably wont stand up.

Well, this is interesting... Two planets/brown dwarf + planet (19.2 M_J + 8 M_J) found orbiting HW Virginis. The transiting binary system consists of a subdwarf B star (post-red giant star) + red dwarf. This is the first discovery using the eclipse timing method. Also, the planets are circumbinary making them the first known circumbinary planets to have formed from a protoplanetary disk (the first circumbinary planet PSR B1620-26 C that orbits a pulsar in M4 was most likely captured along its parent star PSR B1620-26 B by the pulsar).

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It's interesting that they are circumbinary, but other than that it's yet another system with super-Jovian planets in eccentric orbits. The authors seem keen to classify both objects as planets, even suggesting that they must have accreted mass during the primary's red giant phase. Oops, taboo topic.

I think I agree with timb here (or earlier). We seem to have planet inflation. Some strict taxonomy might help.

I think the current criterion is arbitrary and unphysical, but as long as it's there then publishing astronomers should use it.

The lure of the lights.

*sigh*

I follow the Extrasolar Planets Encyclopaedia, and try to report every discovery it mentions. Systems of massive Jovians may not be terribly fascinating anymore, but I really want to talk about the discoveries rather than semantics.

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Sorry

Circumbinary? And what is the eclipse timing method exactly? If this is a first, i would definate welcome this discovery whatever it is boring planets or not

I did a little calculation and there's a small fun task in it for you guys since i can't remember much math from collage and i'm too lazy looking through it all atm.

OK, if we consider the first discovery to be in 1995 (i know this isn't what http://exoplanet.eu/catalog-all.php?mdAff=stats#tc says, but it is the general thought) and consider those 61 planets found last year, we can do a little calculation on how fast the exoplanet searching is progression making an exponential function of the progress so far (way too early, but i can't wait several years to do this calculation ). So, we have:

Planets discovered in 2007 = 61
n = 13 (13 years since the first discovery of an exoplanet)
x = ? (the progress per year - what i wanted to find out)

Exponential function:
y = (1+x)^13

Here goes...:

61 = (1+x)^13
13\sqr{61} = 1+x
13\sqr{61}-1 = x
x = 0,372 = 37,2% progress per year.

So in 2008 we need 61*1,372=84, which is another 25 exoplanets to go for december.

So let's take a look at the total for each year for a moment:

2008: 354
2009: 486 (first year with more than 100 new exoplanets)
2010: 666 (this is probably where we find imperialist aliens with warp drive, just by new years eve 2010/2011 )
2011: 914
2012: 1254

So 1.000 exoplanets by 2012 in this holds water (isn't that an english expression or just danish?)

Trying to find out when all exoplanets in the galaxy have been discovered - just for fun.

Let's say there are 200*10^9 stars in Milkyway, and each solar system (can we settle something here: Is it called a solar system or a star system?) has 8 exoplanets, so that will be 10^12 exoplanet in total.

y = 10^12 (exoplanets in Milkyway)
x = 0,372 (progress per year)
n = ? (how many years from year 1995 that we will have all exoplanet discovered)

y = (1+x)^n
10^12 = (1+0,372)^n
10^12 = 1,372^n

So how is it that i can isolate n in this equation? I just can't remember what i learnt at the university

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log (10^12) = log (1372^n)
log (10^12) = n*log (1372)
log (10^12) / log (1372) = n
12 / log (1372) = n
3.825- = n

Sorry. Was that a decimal?

12 / log (1 decimal 372) = 87.365+

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Circumbinary -- around both components of a binary. The eclipse timing method relies on variations in the time between eclipses in an eclipsing binary due to the motions of the stars induced by orbiting planets. To find out exactly I suggest you read the paper I linked to previously.

Take logarithms.

The HW Virginis system may reveal more about the evolution of planets around stars similar to the Sun as they go through their red giant phase. HW Virginis B, now a red dwarf of mass 0.142, may have originally been a warm brown dwarf that accreted mass from HW Virginis A and spiralled in under the drag of the red giant's extended envelope.

Try 'Planetary System'
http://en.wikipedia.org/wiki/Planetary_system
that distinguishes it from our own solar system, and from any star systems which have multiple stars but no planets.

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The paper has been withdrawn due to a new solution to the data being found.

Seems inconsistent. Notice it's the solar system, ie it's named after the star. That's why some people refer to systems of exoplanets and the star they orbit as stellar systems. You might prefer that terminology if you think that planets are just an external feature of stars, or it could be considered a broader term than "planetary system". Most stars probably have something orbiting them, if only residual rocks and icebergs. Secondary stars, sub-stellar companions, dust disks, planets, rocks and icebergs could all be considered part of a star's "system". How about "planetary system" for systems of planets and "stellar system" (name of star substitutable for "stellar") for the system around and including a star?

I think solar/star system should be a star with its planets and planet system should be that of i.e. Jupiter, Europa, Io and so forth. A moon system should be something that hasn't been found but what i believe exists though rarely to be found - a moon with some items around it. Imagine a star with a planet at 13.9M_jup (or whatever the exact definition of a maximized planet is) with a moon at say 1M_earth, which then had an astroide around it at for instance 1M_moon. That would be a moon system in my eyes. Those are teoretically realistic, right?

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If people said "a star's system" or "a system of planets", "a planet's system" or "a system of moons", etc, there would be no ambiguity.

Sure, though the second smallest body may have trouble keeping its satellite because of the perturbations caused by the larger ones and the likelihood that its own rotation would be synchronous and therefore slow.

Don't see why it would be ambiguity. Just hard to keep track of, but as long as people don't get confused with the not defined expressions today, i guess we can ignore it

Yeah, i figured it should be possible, because there is no difference between the sun, Earth and the moon and if you have a planet at sun's location, a moon at Earth's location and the small body at the location of the moon there is no difference and it is only word juggling (just ignoring the star of that system or put it 1,000AU away).

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http://www.space.com/scienceastronom...nt-planet.html

New paper Stability of the directly imaged multiplanet system HR 8799: resonance and masses says Marois et al's masses and orbits don't work: the system is unstable with a lifetime ~0.1Ma. If the inner two planets are in a 1:2 resonance and the planetary masses are somewhat smaller (which makes them interestingly hot) than Marois estimates, then the system is stable. If the planets are in a 1:2:4 resonance then the system is stable even if the planets are 90% more massive than Marois' estimates.

Good find. Question: these simulations take considerable time I presume? Otherwise Marois would have done them?

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There is a technical report available on the discovery of the 4.5 M_J hot jovian OGLE2-TR-L9. The interesting aspect is that the star is F3, the hottest main sequence star yet found to harbor planets, and it rotates every 2 days which is quite quick. This may have implications for planet formation models, or not. The planet's period is 2.5 days, so the total angular momentum may be about right.

From your report link..."The measured vsini and estimated stellar radius combine to
a rotation period of the host star of ∼1.97±0.04 days. It means
that the rotation of the star is not locked to the orbital period
of OGLE2-TR-L9b. A vsini of 39 km/sec is within the normal
range for stars of this spectral type. The mean vsini of F5 to F0
stars in the solar neighbourhood range from 10^2 to 10^3 km/sec
respectively."

I would guess the 2 days should have stated a 20 day rotation period?

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No, two days matches 39 km/s if you do the calculations. Stars earlier (blech) than about F7 tend to be fast rotators, and this has been related to the scarcity of planet detections around such stars. The story I heard was that later stars rotate slowly because they have transfered most of their angular momentum to a protoplanetary disk. So this detection could challenge that story, but two days actually seems to be a little on the slow side if the normal range of velocities is 10² to 10³ km/s.

Sorry timb, I'm going to pester you again.

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Your question is rather like "how long is a piece of string?". Depending on how many years you want your simulation to run and how many trials you want to make you can invest as much CPU time as you want. To account for chaotic behavior and the fact that the initial elements of the system are always uncertain in the case of exoplanetary systems, the simulation is run many many times. Hundreds of supercomputer CPU years would be common, I think.

Why don't you read the Marois paper if you want to know what computational investigations he made of the orbits?

Nah, you're answer's good enough. Thanks timb!

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Isn't Fomalhaut the hottest main-sequence star yet found to have a planet?

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Good point. My error. That should be hottest fast-rotating main-sequence star yet found to have a planet.