Science. A stellar stream extending 1,600 light-years across the Milky Way

Madrid, 8 (European Press)

Astrophysicists led by Luke Boma of Princeton University have confirmed that open cluster NGC 2516, also known as the Southern Beehive, spans at least 1,600 light-years.

To an Earth-centric stargazer, that might seem as large as 40 full moons, side by side, stretching across the sky.

“Looking back at the past, the existence of this great stellar stream is not very surprising,” said Boma, who presented the discovery at the 238th meeting of the American Astronomical Society (AAS). One explanation might be that the group begins as a narrow group that expands over time to form “tidal tails” that extend in front and behind as it moves through the Milky Way.

“The broader meaning is that there will definitely be other huge open groups like this,” he said. “The visible part of the cluster, where we can easily see stars together, may be just a small part of a much larger stream.”

“I’ve seen the Southern Beehive many times through binoculars under the dark Chilean skies,” said Gaspar Bacos, professor of astrophysics and director of the Princeton Planetary and Life Program. “The cluster adapts very well to binoculars’ view, because its apparent size in the sky is like the tip of my thumb at my arm’s length. And it’s funny to know, thanks to Luke’s research, that the cluster really includes such a large area while my palm is all skyward.”

Puma and colleagues used data from the Transiting Exoplanet Survey Satellite (TESS) to precisely measure the rotation rates of stars determined by Gaia’s study of NGC 2516. The researchers showed that many stars with similar masses all orbit at (or very close to) the same rate, confirming that they were born in the same stellar nursery.

Puma said this open group also had an interesting connection to Greek mythology. “In the southern night sky, NGC 2516 lies near a constellation called Argo Navis, the ship on which Jason and the Argonauts sailed for the Golden Fleece.” “Jason and the Argonauts are navigating a chain of stars created by the open cluster NGC 2516,” he commented.