What Is the Biggest Star?

Space.com ^ | 07/25/18 | Nola Taylor Redd

[Simon Green]

The sun may appear to be the largest star in the sky but that's just because it's the closest. On a stellar scale, it's really quite average — about half of the known stars are larger; half are smaller. The largest known star in the universe is UY Scuti, a hypergiant with a radius around 1,700 times larger than the sun. And it's not alone in dwarfing Earth's dominant star. The largest of all

In 1860, German astronomers at the Bonn Observatory first cataloged UY Scuti, naming it BD -12 5055. During a second detection, the astronomers realized it grows brighter and dimmer over a 740-day period, leading astronomers to classify it as a variable star. The star lies near the center of the Milky Way, roughly 9,500 light-years away.

Located in the constellation Scutum, UY Scuti is a hypergiant, the classification that comes after supergiant, which itself comes after giant. Hypergiants are rare stars that shine very brightly. They lose much of their mass through fast-moving stellar winds.

Of course, all stellar sizes are estimates, based on measurements taken from far away.

"The complication with stars is that they have diffuse edges," wrote astronomer Jillian Scudder of the University of Sussex. "Most stars don't have a rigid surface where the gas ends and vacuum begins, which would have served as a harsh dividing line and easy marker of the end of the star."

Instead, astronomers rely on a star's photosphere, where the star becomes transparent to light and the particles of light, or photons, can escape the star.

"As far as an astrophysicist is concerned, this is the surface of the star, as this is the point at which photons can leave the star," Scudder said.

[glock rocks]

UY Scuti is a hypergiant, the classification that comes after supergiant, which itself comes after giant.

Sort of like canned black olives.

[JPG]

[DungeonMaster]

The sun is so often called average. 45 years ago when I first got interested in astronomy I ignored the sun. Now I find it amazing all the things that go on inside and on the surface of the sun.

Imagine picking any random star and placing it where the sun is and then waiting to see how long before everyone on earth was dead. 99 out of 100 random stars and we'd all be dead very quickly. Maybe the 100th random star would allow us 2 last days.

[IrishBrigade]

‘Located in the constellation Scutum, UY Scuti is a hypergiant’

scutum; Latin, second declension neuter noun meaning ‘shield’; scuti, genitive singular of scutum, expressing the phrase ‘of the shield’...

[Joe Brower]

It was just the Tin Man dropping by for a snack.

[Lou L]

Wow, and I thought Betelgeuse was one of the biggest. I always enjoy these scientific postings!

[SunkenCiv]

What zeestephen said. Anyway, pinging the former APoD list.

[Red Badger]

I’m pretty sure it ain’t Uranus..............

[left that other site]

Thanks for the ping!

I still love our APOD and GGG postings. :-)

[Conan the Librarian]

Thanks for the post!

UY Scuti is one of those things that makes astronomy very interesting. Eta Carina is another.

There be Monsters out there, and UY Scuti is one of the biggest.

[null and void]

That’s a stretch, unless one lives in West Hollywood...

[Red Badger]

The question was ‘What is the Biggest Star?’, not ‘What is the Biggest Black Hole?’................B^)

[null and void]

*nvrmnd*

[SunkenCiv]

I think something wiped out Uranus.

[SunkenCiv]

Thanks for the kind remark!

[Bloody Sam Roberts]

It's a Mutant Star Goat.

[outofsalt]

Canis Majoris is now ranked at about # 6 according to this,

https://www.quora.com/Are-both-UY-Scuti-and-VY-Canis-Majoris-the-same-stars

[PrairieLady2]

Well son of a sun sucker! I’ve never seen anything like that before!

[sargon]

Instead, astronomers rely on a star's photosphere, where the star becomes transparent to light and the particles of light, or photons, can escape the star.

An utterly ignorant statement, exposing the fact that the writer has no knowledge of physics whatsoever...

[PIF]

There’s an outside chance it’s some kind of natural phenomenon, isn’t there?

—

Sure something natural ... what could be more natural that someone’s ship? And there are many of them in the video, most are round, but one has a closeup showing rings, another is tripod shaped. All of them are huge - almost planet sized.

They scoot away because they are full of plasma which they use as fuel or convert into fuel, and to make room for more of them to suck plasma.

Sort of like the photino birds made of Dark Matter in Steve Baxter’s Xeelee series ... trying to convert the sun and all other stars into stable red dwarfs which do not threaten their existence by exploding.