Most scientists believe that the gas giants form much further out (beyond the "snow line") and then spiral in.Originally Posted by William
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Most scientists believe that the gas giants form much further out (beyond the "snow line") and then spiral in.
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Nitpick: The minimum mass of the planet is half the mass of Jupiter. It is probably Jupiter-sized (unless it is a "puffed-up" planet). But since it is not transiting (inclination 90°), we don't know big it is or what its actual mass is (the actual mass increases when the inclination decreases; at 0° we would see the system above its pole).
As t@nn said, it is believed that hot Jupiters migrate beyond the snow line (the line in protoplanetary disk beyond which water ice can form). There are no known mechanisms which could explain how such giant planet could form so close to its star.
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djellison @ Planetary Societ Weblog: Europlanet : CoRoT - Preliminary Results:
New targets not already discussed include another planet around a 14th magnitude sun-like star with a period of 33 days (very long for [transiting] exo-planets), another with a period of 8 days around a type G5 star, and another 1.7 day orbit around a 12.5 magnitude K0 star. He also showed a few graphs of eclipsing binary stars. These produce strange graphs as the two stars (typically one bright and one dim) add up their light, then hide one another, producing weird double peaked graphs. Malcolm also showed a few graphs of magnitude versus time to which he simply said ‘God knows what it is'. Their very first suspected transit was infact a red dwarf star grazing the disc of another star. CoRoT will provide huge amounts of data for a whole swathe of stellar investigation - not just transits and seismology.
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Haven't updated this thread lately, but on the other hand there has been a dearth of new planet announcements until now.
Two new transiting planets:
- HAT-P-4 b, a fairly ordinary if not somewhat inflated planet with a radius of 1.27 RJ
- HD 17156 b, a transiting planet with the largest orbital period by far, 21.2 days and eccentricity, 0.67.
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HD 17156 b is the first discovery by the Transitsearch.org.
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Where the heck is Corot? Wasn't that supposed to be showing us New Earth by now?
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The COROT team has released a single light curve of a transit, but not the auxiliary information on the star (which star? RA, Dec?). They are probably busy analyzing tens or hundreds of transit candidates.
Wait a few months.
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That should make 254 total, 43 for the year.
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But it is certainly not the number of discovered planets in this year. That number is much higher. The number of published planets will also have a jump before the end of the year. There will be a COROT press event sometime in this month or so where some of the detected planets (around 10) will be published.
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Interesting blog. He speculated, after saying he didn't want to, that it might be 20. 10 new ones might just be on track to meet that wild extrapolation, done earlier in this thread, of 61 by the end of the year.
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Two unconfirmed massive planets in very wide orbits from the California-Carnegie team:
- HD 104304 b: m = 17.2 MJ, p = 2752 d, e = 0.38 -- this one could be a low-mass brown dwarf instead
- HD 111031 b: m = 2.87 MJ, p = 5986 d, e = 0.32
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Yet another score for the HATNet:
- HAT-P-5b: m = 1.06 MJ, p = 2.788491 d, e = 0
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HATNet goes to hyperdrive:
- HAT-P-6b: m = 1.057 MJ, r = 1.33 RJ, p = 3.852985 d, e = 0
It should be noted that HATNet project searchs for transiting planets -- all these planets have been found transiting.
Last edited by Kullat Nunu; 2007-Oct-16 at 12:36 PM.
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Three new planets orbiting former type A stars 30% - 60% more massive than the Sun:
- Kappa Coronae Borealis b: m = 1.8 MJ, a = 2.7 AU, p = 1191 d, e = 0.19
- HD 16175 b: m = 4.5 MJ, a = 2.07 AU, p = 856 d, e = 0.48
- HD 167042 b: m = 1.6 MJ, a = 1.3 AU, p = 416.1 d, e = 0.03
The trend suggests that massive stars have on average more massive planets than Sun-like stars. Which is not surprising, since it is already known that low-mass stars have more low-mass companions. It seems that the mass of a planet depends on the mass of its star. In addition, it looks like that more massive stars don't have closely-orbiting planets.
Main sequence type A stars rotate so rapidly that their spectral lines become blurred which makes it impossible to detect planetary signals. When the hydrogen fusion ceases at the core of an A star, it changes to an orange subgiant such as these. Fortunately for us, at that phase the star rotates slowly and is spectroscopically quiet which allows the search for planets.
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This makes sense as the more massive accretion disks should produce a more massive host and planetary system, I assume.
I wonder why not? Did they once exist but migrated into their host during the early formation years?In addition, it looks like that more massive stars don't have closely-orbiting planets.
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Who knows? Maybe the protoplanetary disks of more massive stars have bigger central holes compared to the protoplanetary disks of Sun-like stars. If there is no material left inside a planet's orbit, it can't migrate further. This is also the likely reason why hot Jupiters didn't get eaten.
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That makes sense; there's likely little one can fatten-up on when one is in a lion's den. I still like the migration idea since it has more drama.
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Could be that the inner disk is royally disrupted and blown outward by the newborn's stellar winds. Figuring that the bigger the star, the harder it belches.
Order of Kilopi
Yes, that is likely. Further, the big stars, I think, are known to rotate rapidly, at least in the early years. This should also cause lighter materials to push outward since the wind is being slung.
But what happens to the heavier objects formed in the disk? Will the disk dynamics create density waves causing them to grow and migrate inward at a faster rate, thus limiting, somewhat, the amount of void around the star? Also, there was one model I saw illustrated that showed an inward, and outward, flow of material caused by an orbiting planet in the disk. What would be the net effect of this?
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Not sure, the math to calculate that is so far above my head, it can't be seen with a radio telescope...
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Hi!
What about these highly eccentric jovians?
HD 156846 (Ophiuchus)
HD 4113 (Sculptor)
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After a long hiatus, a new transiting OGLE planet:
- OGLE-TR-182b: m = 1.01 MJ, r = 1.13 RJ, a = 0.051 AU, p = 3.9791 d, e = 0
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Hello again Edasich, and welcome to the forum. Nice to see other Extrasolar Visionists on this forum.
You beat me only a few minutes...
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No problem.
I think there will be some interesting stuff here
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Not one, two, but three transiting planets from the SuperWASP project:
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Only two more transiting planets and the number of them discovered in 2007 is equal to all transiting planets discovered in previous years put together.
And the COROT team hasn't even published its results yet!
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From your post #129...
Looks like it is getting pretty close to that number.
This makes 51 for 2007. [I'm still hoping for 62.]
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Scientists Discover New Member of Exoplanet Family -- "new findings about a planetary system similar to our own". Details to be revealed next Tuesday.
Debra Fischer & Geoff Marcy means this is a radial velocity discovery.
Order of Kilopi
Wow, that looks great!!
Of course, I am a bit dubious since they show a yellow star in their depiction. I hope that is not the basis of their claim!
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