Discovery of a strange galaxy that has no stars at all: ScienceAlert

A newly discovered object expands our understanding of what makes up a galaxy.

This massive blob called J0613+52, about 270 million light-years away, appears to contain no stars at all. At least, nothing to be seen. It's just a fog made of the kind of interstellar gas found in normal galaxies, drifting along on its own like a completely hideous person.

Its mass and motion seem normal for what we would expect from a spiral galaxy… In fact, if you extracted stars from a spiral galaxy like the Milky Way or Andromeda, J0613+52 is pretty much what you'd end up with.

According to a team of astronomers led by astrophysicist Karen O'Neill of Green Bank Observatory, this may be the first discovery of a primordial galaxy in the nearby universe, a galaxy composed mostly of gas that formed at the beginning of time.

The space area where J0613+52 can be found. (O'Neill et al.)

The discovery – which was made purely by chance – It was presented At the 243rd Meeting of the American Astronomical Society.

“GBT was mistakenly directed to the wrong coordinates and this object was found.” O'Neill says. “It's a galaxy made only of gas, and it has no visible stars. The stars could be there, but we can't see them.”

The researchers were using the Green Bank Observatory to search and study what are known as low surface brightness, or LSB, galaxies. These are galaxies, mostly small dwarf galaxies, that do not emit much light, because most of their content is made up of gas and dark matter. Compared to other galaxies, it contains very few stars.

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The researchers were looking to measure the gas content and mass of LSB galaxies, so the survey focused on searching for gas, rather than stars, using the Green Bank Telescope, the Arecibo Telescope, and the Nançay Radio Telescope. Green Bank and Nançay were supposed to be looking at the same patch of sky in part of the survey, but someone made a typo in Green Bank's coordinates, pointing instead to a patch of sky that had never been examined before.

Image showing the Doppler shift of light determined by the team. (O'Neill et al.)

There, researchers found a signature of hydrogen gas, with a strength expected from a spiral galaxy. Researchers were even able to determine a Doppler shift of radio waves associated with the galaxy's rotation, which lengthens wavelengths in the part rotating away from us, and shortens wavelengths in the part rotating toward us.

But in the Green Bank Radio data, there was no sign of stars at all. The object appears to be isolated and undisturbed, having not experienced any gravitational interactions over 13.8 billion years that would have disrupted the gas, either tearing it apart, or pushing it into the masses needed to significantly stimulate star formation. This makes J0613+52 an object unlike any other we've seen before.

“What we know is that it is an incredibly gas-rich galaxy.” O'Neill says.

“It does not show star formation as we would expect, perhaps because its gas is so diffuse. At the same time, it is too far away from other galaxies to help stimulate star formation by any encounters. J0613+52 appears to be equally unaffected.” And undeveloped. “This may be our first discovery of a nearby galaxy composed of primordial gas.”

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Because it's so dark, studying it deeper can be difficult. It may not be possible to see it at wavelengths other than radio. This appears to be rare, as this is the first of its kind ever discovered. The researchers point out that it may be useful to scan the sky with powerful radio telescopes to search for other objects like it.

Given the way matter in the universe appears to be clumped together, J0613+52 may be unique, at least in near space — a cloud of gas unchanged since the dawn of the universe, drifting on its own for billions of years. . What an absolute wonder.

The discovery has been made At the 243rd Meeting of the American Astronomical Society.

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