A Planet Literally Boils Under the Heat of Its Star

The Bad Astronomer writes "Astronomers have found what appears to be a planet so hot it's literally vaporizing, boiling away from the heat of its star. KIC 12557548b was found using the transit method, periodically blocking some light from its star as it orbits around. But the amount of light blocked changes every transit. Given it's less than a million miles from the surface of the star, astronomers interpret this (PDF) as the planet itself turning to vapor, and the expanding cloud of rock-laden gas is what's blocking the starlight. The planet is most likely somewhat bigger than Mercury, but losing 100,000 tons of matter every second it'll only be around another few hundred million years."

Re:100,000 tons

[AtariEric]

Hopefully, that's metric tons; and therefore mass, not weight.

Re:100,000 tons

[Rhywden]

A ton is a unit of mass and thus independent of gravity. I also dare say that we're talking about metric tons here, i.e. 1 ton = 10E3 Kg.

Re:This Doesn't Make Sense

[v1]

I'm no rocket scientist so maybe I'm missing something here, but if a planet loses mass in this way it should not affect its orbit. Take as an example, lets say some supergiant transformer takes out his sword and slices the moon in half. Each half has 50% of the mass of the moon. That doesn't cause both pieces of the moon to plummet toward the sun.

(circular) orbit is the equilibrium reached when the gravitational pull toward an attractor is balanced by the inertial energy of the mass which is trying to move the object away from the attractor. Both have a linear relation to change of mass of the object in orbit, and the two contribute an opposite force, so if you change the mass, the object should remain in the same orbit. (if you lower the mass, you lower the gravitational attraction and lower the inertial energy)

This is the same reason astronauts don't get hurled off into space when they step out of their spacecraft. And the spacecraft also remains in the same orbit when the astronaut leaves it.

If you want to make something fall toward its attractor, you need to slow it down. That lowers its inertial energy without affecting the gravitational attraction. Or let it collide with a mass that does not have the same inertial vector. (increasing the mass attraction, without an equal increase in overall inertial energy)

I suppose another basic way to view an object in orbit is to view all the particles of the object as independently in the same orbit. Group them any way you want, they are still in the same orbit. Even if some of it turns from rock to gas. The gas remains in the same orbit along with the rock.