Sharpless 273, Fox Fur Nebula

Tadpole Nebula (IC 410)

MilkyWay by nairam13

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Strange star system may hold first evidence of an ultra-rare 'dark matter star'

In a distant star system, a sunlike star orbits an invisible object that may be the first example of a 'boson star' made of dark matter, new research suggests.

Astronomers long thought that a peculiar star system observed by the European Space Agency’s Gaia satellite was a simple case of a star orbiting a black hole.

But now, two astronomers are challenging that claim, finding that the evidence suggests something far stranger: Possibly, a never-before-seen type of star made of invisible dark matter. Their research, which has yet to be peer-reviewed, was published April 18 on the preprint server arXiv.

The system itself consists of a sunlike star and, well, something else. The star weighs a little less than the sun (0.93 solar mass) and has roughly the same chemical abundance as the sun. Its mysterious companion is much more massive — around 11 solar masses. The objects orbit each other at a distance of 1.4 astronomical units, about the distance at which Mars orbits the sun, making a complete orbit every 188 days.

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El Gordo Galaxy Cluster

IC-1396, The Elephant’s Trunk Nebula by CosmicWreckingBall

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Very Large Telescope sees star dance around supermassive black hole, proves Einstein right

This research was presented in the paper "Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole" to appear in Astronomy & Astrophysics.

Observations made with ESO’s Very Large Telescope (VLT) have revealed for the first time that a star orbiting the supermassive black hole at the centre of the Milky Way moves just as predicted by Einstein’s general theory of relativity. Its orbit is shaped like a rosette and not like an ellipse as predicted by Newton’s theory of gravity. This long-sought-after result was made possible by increasingly precise measurements over nearly 30 years, which have enabled scientists to unlock the mysteries of the behemoth lurking at the heart of our galaxy.

“Einstein’s General Relativity predicts that bound orbits of one object around another are not closed, as in Newtonian Gravity, but precess forwards in the plane of motion. This famous effect—first seen in the orbit of the planet Mercury around the Sun—was the first evidence in favour of General Relativity. One hundred years later we have now detected the same effect in the motion of a star orbiting the compact radio source Sagittarius A* at the centre of the Milky Way. This observational breakthrough strengthens the evidence that Sagittarius A* must be a supermassive black hole of 4 million times the mass of the Sun,” says Reinhard Genzel, Director at the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany and the architect of the 30-year-long programme that led to this result.

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The pixel scale of the Hubble Space Telescope’s WFC3 camera with the Event Horizon Telescope for Black Hole image by akashdalai

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Sharpless 273, Fox Fur Nebula