‘Bridge’ of stars connects two of the most famous galaxies around

8 Feb 20179 Shares

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A number of photos were taken at the Paranal observatory in Chile and stitched together to produce this panorama. The Milky Way is arching across the entire picture, while the Large and the Small Magellanic Clouds can be seen just above the horizon. Image: D Erkal

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A new investigation into the two Magellanic Cloud galaxies has discovered a ‘bridge’ of stars between them, with the larger galaxy ripping some away from its smaller neighbour.

The Magellanic Clouds, best visible to astronomers in the southern hemisphere, have proved somewhat of an enigma to scientists.

The two largest satellite galaxies of the Milky Way, the duo have been the subject of intense investigation this millennium, thanks to a galactic stellar census undertaken by the European Space Agency observatory, Gaia.

Galaxy

Among all space instruments, Gaia has the largest number of pixels to take images of the entire sky.

A research team led by the University of Cambridge has been poring over Magellanic Cloud data in recent months, establishing a direct link between the two.

Streams of stars form when a dwarf galaxy or star cluster feels the tidal force of the larger body around which they orbit. Slowly, stars start to abandon the satellite, leaving a luminous trace on the sky and thus revealing the satellite’s orbit.

The Magellanic Clouds in the night sky. The Large and the Small Magellanic Clouds are visible. The Clouds are moving towards the bottom left corner. Image: V. Belokurov and A. Mellinger

The Magellanic Clouds in the night sky. The Large and the Small Magellanic Clouds are visible, moving towards the bottom left corner. Image: V Belokurov and A Mellinger

“Stellar streams around the Clouds were predicted but never observed,” said Dr Vasily Belokurov, who worked on the study.

“Having marked the locations of the Gaia RR Lyrae on the sky, we were surprised to see a narrow bridge-like structure connecting the two clouds.

The white line gives the approximate (average) track of the stellar bridge and the blue line shows the track of the gaseous bridge. The stars and the gas do not follow the same path. Image: V. Belokurov and A. Mellinger

The white line gives the approximate (average) track of the stellar bridge while the blue line shows the track of the gaseous bridge. The stars and the gas do not follow the same path. Image: V Belokurov and A Mellinger

“We believe that, at least in part, this ‘bridge’ is composed of stars stripped from the Small Cloud by the Large. The rest may actually be the Large Magellanic Cloud stars pulled from it by the Milky Way.”

Pale white veils and the narrow bridge between the Clouds represent the distribution of the RR Lyrae stars detected with the data from the Gaia satellite. Image: V. Belokurov, D. Erkal and A. Mellinger

Pale white veils and the narrow bridge between the galaxies represent the distribution of the RR Lyrae stars detected with data from the Gaia satellite. Image: V Belokurov, D Erkal and A Mellinger

Gordon Hunt is a journalist at Siliconrepublic.com

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