Sensationalist headline. Actually just a candidate for supporting liquid water (and then only for some of it's fairly elliptic orbit).
And it's pretty damn big, so not likely to be a rock, more like a gas giant (If it _doesn't _ have a large gaseous atmosphere it would I think be the biggest rock planet ever discovered.)
So "habitable exo-planet" is stretching things............... a lot.
Yeah well it's an unfortunate by-product of a) research institutions feeling the pressure to spin their output in a way which is consumer-friendly and b) the publishing industry turning that spin into an absurd attention-grabbing headline.
It's more a by-product of the fact that the Kepler mission has produced so many planet candidates (with an estimated ~50% false positive rate) that it would require about 30 years of telescope time on the world's largest telescopes to actually confirm that the stars have planets.
Can you cite a source for your 50% false positive rate? I found a source[1] that argues for a ten percent false positive rate.
What do you mean to "confirm" that the stars have planets? I could imagine, directly imaging them is confirmation, but, as I understand it, that's nearly impossible for the average exoplanet we've found. What types of data are Kepler and COROT lacking which you desire for confirmation?
The false positive rate seems to have been revised to 40% since I last checked, but my reference is here (though they cite the Morton & Johnson paper, too):
The 10% false positive rate is for rank 2 targets, but the majority of targets are rank 4, which have a 40% false positive rate. (See section 2.2.2)
To confirm that the stars have planets, one would do spectroscopic follow up. You would see the slight wobbling of the host star due to the gravitational influence of the planet, and this would manifest itself in a slight Doppler shifting of the spectral lines of the host star. The problem is that most of the stars that Kepler is observing are so faint that ground-based spectroscopic follow-up is impossible except on the largest telescopes, and even then you can only do it for a handful of the thousands of candidates that Kepler is discovering.
By its nature, a big rocky planet could hold on to a thicker atmosphere; it would also have greater internal heat, a thinner crust, so more geologic activity, greater volcanism.
And it's pretty damn big, so not likely to be a rock, more like a gas giant (If it _doesn't _ have a large gaseous atmosphere it would I think be the biggest rock planet ever discovered.)
So "habitable exo-planet" is stretching things............... a lot.