Pardon me, I’ve got gas #2

Planets! Everyone loves planets, right? After all, some of my best friends live on planets. But the first thing I’ve heard this year which piqued my interest was a little story about a planet named KOI-314c.

As usual, this may not be a particularly inspiring name, but KOI-314c is a curious little world. For a start, it’s more or less Earth-sized. Detected using data gathered by Kepler, this little world is the lightest ever to have had both its mass and size measured. And therein lies the interesting thing about it.

You see, KOI-314c may be roughly the same mass as Earth, but to quote David Kipping from Harvard Smithsonian, it’s “certainly not Earth-like”. In fact, its diameter is 60% larger than Earth’s, which suggests that it has a very thick, dense atmosphere. Either that or, I might speculate, it’s also composed of relatively low density material – though I’m unable to speculate exactly how that might occur. That would still be only be half the story though. This planet’s of such a low density that the only conclusion has to be that it contains a lot of gas.

Yes I know it's unlikely to have an Earthy blue atmosphere, but I'm allowed to use a little artistic license, right?

In any case, being only around 30% denser than water implies that its atmosphere must be mostly hydrogen and helium. A heavy atmosphere hundreds of kilometres deep. In fact, given its tight orbit with a red dwarf companion star (with a year lasting just 23 Earth days and an average surface temperature over 100°C) it’s possible that KOI-314c is a chthonian planet in the making – a former gas giant in the process of losing its atmosphere.

In any case, it’s an interesting little world. Also, seeing as it transits its host star, it should be relatively easy to probe its atmosphere and test that hypothesis. With modern technology, it’s actually not all that difficult to peer into the atmosphere of a transiting exoplanet. All you need to do is point a telescope in the right direction at the right time and grab a spectrum as the planet passes in front of its parent star. In fact, it’s already been done!

Admittedly, the problem here is that red dwarfs are noisy little beasts with messy spectra. They’re also very dim, so transit spectroscopy on little KOI-314c would be difficult. To say the least. But I’m pretty sure it’s possible…

(But don’t quote me on that!)

Source: Harvard Smithsonian
Image credit: Invader Xan/
(It always feels so meta to include my own name as a credit line…)

About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
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2 Responses to Pardon me, I’ve got gas #2

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