Kepler 10b

Here’s a heads-up on an impressively weird new exoplanet.

Kepler-10b (‘Kepler 10’ being the designation for the star and ‘b’ meaning it’s the first planetary companion detected aroudn that star) apparently has both a transit measurement and a radial velocity measurement. This means a direct measurement of its radius and also a direct measurement of its mass. In addition these numbers tell us about its orbit.

So, what we know … it’s 1.4 Earth diameters wide, it masses 4.6 Earth masses and it orbits its star at the absurdly close distance of 3 million or so kilometres. (The Earth, by contrast, averages about 149 million kilometres from the Sun.) So it’s a very reasonable bet that 10b will have a scorchingly hot surface!

In fact, day time temperatures will probably be a couple of thousand degrees. On the planet’s sunward face, the surface will likely be a hemisphere-wrapping sea of molten rock. Presumably the nightside will be cooler, as it faces space, not Kepler-10. So there will possibly be a crust of solid rock on the nightside.

Also, I used ‘night’ and ‘day’ deliberately for these hemispheres. An object this clsoe to its sun is almost certainly tidally locked – that is, it spins in the same time it takes to orbit the star, so that one hemisphere is permanently sun-facing and one pointed forever away.

Kepler-10b is a very, very weird planet. (And that’s the way I like them!)


3 Responses to “Kepler 10b”

  1. I think the artist’s impression on the BBC site captured the diffrence between the two sides quite nicely. Lets say I wouldn’t want to go any where near the day side of a planet like this. I’m wondering whether you’d see volacanic activity on the night side. With the day side being pretty well molten I’d have thought there would be some pretty powerful convection currents going on there that would effectively recycle the planet. I bet the gravitational forces it experiences are pretty extreme too.

    • I think vulcanism is pretty likely! If the orbit is even a little eccentric, then the star’s tides will stretch and squeeze the planet, like Jupiter does to Io, and that will give the mantle a good stir.

      Actually, another thought. At 3m km from its star, it must be at several thousand Celsius – which might actually be hot enough for rocky elements to evaporate. (Titanium oxide vapour, for instance, is present in the atmospheres of M dwarf stars, at about 3000 – 2500K.) Or, to phrase it another way, it’s not beyond imagining that there might be a lava weather system. It could literally rain lava!

  2. […] Recently, I mentioned Kepler 10b. […]

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