Massive Exoplanet Discovered, Challenges Established Planet Formation Theories

sfcrazy writes "A giant exoplanet that is in the most distant orbit ever seen around its host star, has been recently discovered. Dubbed HD 106906 b, the newly discovered planet is relatively young (13 million years old, compare this to our 4.5 billion years old Earth) and bigger than any other planet discovered till date. It is 11 times the size of Jupiter, and that's what makes it a most singular discovery."

Re:Can someone who knows about astronomy fill me i

[Virtucon]

http://www.scientificamerican.com/article.cfm?id=how-do-scientists-determi [scientificamerican.com]

Re:11 times the size of Jupiter?

[SJHillman]

If it's 11 times the diameter, then gravity would be pretty tame at the surface unless it's extremely dense. For example, Jupiter's diameter is 11.2 times that of Earth, but the surface gravity is only 2.64 times that of Earth. Saturn and Uranus both have equatorial surface gravities roughly equal to Venus, in spite of being 9.44 and 4 Earth diameters, respectively.

Source: http://www.windows2universe.org/our_solar_system/planets_table.html [windows2universe.org]

Re:Can someone who knows about astronomy fill me i

[bigHairyDog]

OK I answered my own question with some googling.

The age of the exoplanet is not independently derived, but instead, taken from the age of the host star. This too can be difficult to determine. For isolated stars, there are precious few methods (such as gyrochronology) and they generally have large errors associated with them. Thus, instead of looking for isolated stars, astronomers searching for young exoplanets have tended to focus on clusters which can be dated more easily using the main sequence turn off method.

http://www.universetoday.com/76495/the-hunt-for-young-exoplanets/ [universetoday.com]

Re:Upper limit on planets? Lower limit on stars

[Zephyn]

That's the mass threshold for deuterium fusion. No fusion = planet, deuterium fusion = brown dwarf, hydrogen fusion = main sequence star.

So at 11 Jovian masses, the planet is close, but not quite big enough to reach brown dwarf status.

headline isn't quite correct

[The Bad Astronomer]

The headline as submitted isn't really correct. The planet is not the biggest found; there are several whose mass may be larger, like the exoplanets announced just last week (and this planet has 11 times the mass of Jupiter; we don't know its actual size). The real issue with HD 106906 b is that it is so far out from its parent star, much farther out than planets with that ass should form. Either it formed farther in and got tossed out (which is unlikely) or it formed where it was, which current theories say is difficult; usually objects forming that far out have much higher mass. I explain all this in my own blog post about it [slate.com].

Re:Can someone who knows about astronomy fill me i

[Shadowmist]

And what exactly do we know about planet formation? If anything, we have a hunch how our system formed, but it's neither certain nor do we have any clue whether it's the norm. We already know that our system is in some ways "special", from the rather high amount of trans-HE material to its position in the galactic disc to the mere fact that it's not a multi-star system.

Actually we still don't know enough about stellar formation to determine how far from the norm, the Solar System actually is. The reason that we find so many oddball systems and planets is that those are the easiest systems and planets to find. We are in a form golden area of our Galaxy, far enough from the galactic center that we're not subject to it's nasty radiation and stellar activity, yet not so far that we'd lack in heavy elements. Keep in mind also that most planet detection methods rely on the target solar system being oriented edge on towards us so the planet can intercept the star's light by passing between it and us. That's going to leave a lot out.