What we thought was a perfectly normal spiral galaxy not far from the Milky Way has revealed a hidden surprise.
Located about 56 million light-years away, NGC 4632 is surrounded by a massive ring of gas that wraps around the galaxy at a very tilted angle relative to its galaxy. Hungarian plane. Why haven’t we seen it yet? It is invisible in most of the electromagnetic spectrum, and only appears when we stare at the sky with radio telescopes.
This discovery could place NGC 4632 in the category of extremely rare galaxies known as Polar ring galaxies But it also suggests that these galaxies may not be as rare as we thought. Alternatively, NGC 4632 may mean we’ve been looking at it in the wrong light.
“The results suggest that between 1 and 3 percent of nearby galaxies may contain gaseous polar rings, a much higher proportion than optical telescopes suggest. Polar ring galaxies may be more common than previously thought.” says astrophysicist Nathan Degg From Queen’s University in Canada.
“Although this is not the first time astronomers have observed polar ring galaxies, NGC 4632 is the first time it has been observed using ASKAP, and there may be more to come.”
Polar ring galaxies are pretty much what they sound like: galaxies containing a ring of material — dust, gas, and stars — orbiting around or near the galaxy’s poles; that it, Perpendicular to the galactic plane.
They usually look quite stunning, with their sparkling rings angled like a torus Von Braun space station.
We don’t know how they got this way, but there it is Two current main contenders.
The first is that matter travels along the cosmic web through intergalactic space, and ends up in orbit around the galaxy, forming part of it.
The second, more plausible explanation is that the ring consists of gravitationally engulfed matter from another galaxy that approached and interacted with the polar ring galaxy.
Interestingly, they tend to be galaxies lenticular And Elliptical Species containing polar rings. These are mysterious, disorganized galaxies, without the well-defined spiral arms we see in galaxies like the Milky Way.
Visual observations revealed polar rings around it About 0.5 percent From nearby lenticular galaxies. But there is much more to the universe than meets our limited human eyes.
However, Deeg and an international team of astronomers did not necessarily expect a hidden polar ring around spiral galaxy NGC 4632.
Featured in data collected by the Widefield ASKAP L-band Legacy All-sky Blind Survey (Wallaby) was conducted using the Australian Pathfinder Square Kilometer Array, a powerful radio telescope array located in the Western Australian desert. The goal of WALLABY is to survey hundreds of thousands of galaxies in the southern sky, in order to map the distribution of gas in them.
“NGC 4632 is one of two polar ring galaxies we identified out of 600 galaxies mapped in our first small WALLABY survey.” Says astronomer Barbil Korybalski Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia.
“Using ASKAP over the coming years we expect to detect more than 200,000 hydrogen-rich galaxies, including many unusual galaxies such as those with polar rings.”
NGC 4632 doesn’t immediately tell us how polar ring galaxies get their rings. But it – along with the second polar ring spiral galaxy that the team discovered, NGC 6156 – indicates that there may be a large number of them that we have not found yet.
It could also indicate that the formation mechanism of polar ring spiral galaxies is different from that of previously identified polar ring galaxies.
The team hopes that further observations will reveal more of these mysterious objects. This should reveal whether the type of ring – gaseous or star-filled – is related to the structure of the host galaxy. We’ll also take a closer look at NGC 4632 and NGC 6156.
“As better observations and more sophisticated models of both galaxies become available, it will be possible to constrain the parameters of the progenitor ring (if indeed it was formed via mergers or flybys).” The researchers write.
“Understanding whether these result from interactions or gas accretion will provide constraints on galaxy formation and evolution.”
The research was published in Monthly Notices of the Royal Astronomical Society.
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