LOFAR discovers largest carbon atoms outside our Milky Way

© Leah Morabito (Background Image credit: J. Gallagher, M. Mountain, and P. Puxley)

An international team of astronomers, led by Leah Morabito (Leiden Observatory) and involving ASTRON astronomer Raymond Oonk, has for the first time discovered the largest carbon atoms outside our Milky Way in the nearby galaxy M82. This discovery was carried out with the LOFAR radio telescope. In the future astronomers will be able to use these large Carbon atoms to measure how cold and how dense the gas around these atoms is. The results are published in the journal Astrophysical Journal Letters on 28 October.

Carbon atoms are about half a million times smaller than the average thickness of a human hair, but in very cold and sparse gas they can be up to a billion times larger(*). The weak spectral signature of these very large atoms can be observed at very low radio frequencies.

In the past most radio telescopes have either not been sensitive enough or not been tuned to the right frequencies to be able to detect these lines outside of our own Galaxy. However, the LOFAR radio telescope, that stretches from the northeast of the Netherlands across Europe, is perfect for these kind of observations because of its wide frequency range and excellent sensitivity.

The LOFAR study of the nearby starburst galaxy M82 has now, for the first time, been able to detect the spectral signature from large carbon atoms outside of our own Milky Way. These observations, in combination with future measurements, present us with a new tool to study the properties of the cold and sparse gas in M82 and what role this gas plays in evolution of this galaxy.

(*) Such large atoms are called Rydberg atoms (see e.g. wikipedia).