Kepler Discovers 'Phantom' Exoplanet

astroengine writes "The Kepler space telescope has spotted an extra-solar planet with a very odd orbit. Sometimes Kepler-19b slows down by five minutes during its 9-day orbit. Other times it speeds up by five minutes. Johannes Kelper's laws of orbital dynamics never said a celestial body can arbitrarily speed up and slow down; another planetary body must therefore be gravitationally acting on Kepler-19b. Enter Kepler-19c, a world that hasn't been observed, but its gravitational effects have. This is an unprecedented discovery, one that could potentially be used in multi-planetary star systems to discover more 'phantom' worlds that would have otherwise gone unnoticed."

Comments

Not 'unprecedented'

[bennetts2]

This is an unprecedented discovery

Er, no. Neptune and Pluto were both discovered because of the perturbations they caused of the orbit of Uranus.

Re:Not 'unprecedented'

[nedlohs]

They aren't exoplanets, and hence not a precedent.

Re:Unprecedented?

[Anonymous Coward]

From TFA:

This is the first time that an "invisible" exoplanet has been discovered through its gravitational influence on another exoplanet.

So that's the exact criterion that makes it unprecedented.

Binary planet?

[gstrickler]

+/- 5 minutes in a 9 day orbit is a huge variation. This almost has to be a binary planet system, or planet with a massive moon, or something similar. Enough gravitational force to slow or speed up a planet large enough that we can detect it by transit dimming of it's star 650 LY from Earth, that's either a really light planet, or it's got a massive companion orbiting it. The other possibility is that there is a dark star (white/brown dwarf) orbiting the same star, but we should be able to detect that wobble via doppler shift, so the companion moon/planet seems more likely.

Re:Binary planet?

[Mt._Honkey]

I did the calculation, after finding the details of the planet on the Kepler website. They don't have a mass value for 19b, just an upper limit at 14 earth masses. I just plugged in a value of 10 earth masses for my calculation, and I get 10^30 J, or about 200 zettatons of TNT equivalent, or enough energy to accelerate 3.6 billion pounds of bacon to the speed of the LHC beam.