In cold clouds of interstellar gas, carbon hides inside carbon monoxide (CO) molecules, like sugar dissolved in tea. But near hot, massive stars, this 'tea' boils: harsh radiation tears the molecules apart, and carbon escapes as lone atoms or ions. Seeing all three states at once from Earth was impossible because the atmosphere absorbs the necessary wavelengths.
The Antarctic Terahertz Explorer telescope, with a 60-centimeter mirror, installed at Dome A station, has for the first time mapped two states of carbon simultaneously in two regions of active star formation. The data were combined with already known maps of ionized carbon. The result is a complete picture of the cycle: carbon in molecules in some places, in atoms in others, and in ions elsewhere.
This is the first successful survey of its kind from Dome A — a site with the driest and clearest skies for submillimeter waves. The result not only proves that Antarctic astronomy works but also shows that feedback from massive stars stirs up cloud chemistry more than previously thought. The carbon cycle in space turns out to be livelier than in our kitchen.
Dome A station sits at an altitude of over 4000 meters, and the air there is so dry that it contains less water vapor than the Atacama Desert — making it an ideal spot for submillimeter observations.
In Liu Cixin's novel 'The Three-Body Problem,' a signal from space is received using a giant antenna in the mountains — Antarctic telescopes solve the same problem, but for carbon molecules.