Details of a factory of stars and planets in a far away galaxy seen by the ALMA telescope

Pictures of the galaxy SDP.81. On the left a picture taken by the Hubble Space Telescope. In the middle, the galaxy as an Einsetin ring and on the left as it's seen after being processed to eliminate the gravitational lensing distorsion (Image ALMA (NRAO/ESO/NAOJ)/Y. Tamura (The University of Tokyo)/Mark Swinbank (Durham University))
Pictures of the galaxy SDP.81. On the left a picture taken by the Hubble Space Telescope. In the middle, the galaxy as an Einsetin ring and on the left as it’s seen after being processed to eliminate the gravitational lensing distorsion (Image ALMA (NRAO/ESO/NAOJ)/Y. Tamura (The University of Tokyo)/Mark Swinbank (Durham University))

ESO’s telescope ALMA (Atacama Large Millimeter / submillimeter Array) in Chile allowed to take the most detailed images ever obtained of a galaxy called HATLAS J090311.6+003906 or SDP.81. It’s about 11.4 billion light years from Earth and its light is distorted by the phenomenon called gravitational lensing. A galaxy between it and the Earth distorts its light with its huge gravity and the result is that we see an almost perfect ring, called an Einstein ring.

ALMA is a telescope formed by a series of antennas completed just over two years ago. They form an array that works in perfect sync as a single giant telescope. In this way, it was able to capture images of the galaxy SDP.81 with a resolution up to six times higher than those taken at infrareds by the Hubble space telescope.

These new images were analyzed independently by seven different groups of scientists. This amount of research has revealed a lot of new information on the galaxy SDP.81 including its internal structures. In particular, it’s been possible to identify dust clouds that are believed to be factories of solar systems.

The details never seen before were obtained using sophisticated algorithms to process the images to compensate for the distortion caused by the effect of gravitational lensing. In essence, in the resulting reconstruction the ring visible in the center of the image has become a proper photo of a galaxy visible in the right section of the image.

We see the galaxy SDP.81 as it was 11.4 billion years ago, when the universe was only about 2.4 billion years old. The consequence is that we’re seeing the formation of ancient stars and that many of them are already dead. Those huge gas clouds have been compared to a much larger version of the Orion Nebula, and a substantial amount of stars may have be born there.

ALMA is allowing observations of very distant galaxies in unprecedented details. In the case of the galaxy SDP.81, the analyzes still go on, for example to see if it’s the result of a collision between two galaxies. The opportunity to examine in such depth distant areas of the universe is a great help for astronomical research.



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