A chthonian planet ( /ˈkθoʊniən/, sometimes misspelled 'cthonian') is a hypothetical class of celestial objects resulting from the stripping away of a gas giant's hydrogen and helium atmosphere and outer layers, which is called hydrodynamic escape. Such atmospheric stripping is a likely result of proximity to a star. The remaining rocky or metallic core would resemble a terrestrial planet in many respects.
HD 209458 b is an example of a planet that is in the process of having its atmosphere stripped away, though it is not itself a chthonian planet nor is it expected to become one in the near future.
COROT-7b may be the first chthonian planet discovered, followed by Kepler-10b.
Chthonia (from Greek: χθων) means "of the Earth". The term was coined by Hébrard et al., since the term chthonian generally refers to Greek deities from the infernal underground.
Famous quotes containing the words chthonian and/or planet:
“It is not menstrual blood per se which disturbs the imagination—unstanchable as that red flood may be—but rather the albumen in the blood, the uterine shreds, placental jellyfish of the female sea. This is the chthonian matrix from which we rose. We have an evolutionary revulsion from slime, our site of biologic origins. Every month, it is woman’s fate to face the abyss of time and being, the abyss which is herself.”
—Camille Paglia (b. 1947)
“Spring is strong and virtuous,
Broad-sowing, cheerful, plenteous,
Quickening underneath the mould
Grains beyond the price of gold.
So deep and large her bounties are,
That one broad, long midsummer day
Shall to the planet overpay
The ravage of a year of war.”
—Ralph Waldo Emerson (1803–1882)