Post by swamprat on Aug 4, 2019 16:46:37 GMT
Size Matters
What Is the Biggest Star?
By Nola Taylor Redd | July 26, 2018
The radius of UY Scuti is about 1,700 times larger than the sun's radius.
(Image: © Philip Park)
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.
If UY Scuti replaced the sun in the center of the solar system, its photosphere would extend just beyond the orbit of Jupiter. The nebula of gas stripped from the star extends even farther out, beyond the orbit of Pluto to 400 times time the Earth-sun distance.
But UY Scuti doesn't remain stagnant. Scudder pointed out that the star varies in brightness as it varies in radius, with a margin of error of about 192 solar radii. These errors could allow other stars to beat out UY Scuti in the race for size. In fact, there are as many as 30 stars whose radii fit within UY Scuti's smallest estimated size, so it shouldn't sit too securely on its throne.
When speaking of bigness among stars, you have to define your terms. There are very heavy stars. And there are giganticstars, in terms of sheer physical size. The heaviest star is thought to be R136a1. It’s 265 times more massive than our sun – nearly twice as massive as what astronomers thought was possible. It’s the most massive star known at this time. But there are more ways than one to measure stars’ bigness. In terms of sheer physical size, the star UY Scuti is considered the biggest known. It’s only 30 times the sun’s mass, but has a radius more than 1,700 greater than the sun.
UY Scuti vs Earth – Let’s suppose the Earth is the size of a football (soccer, America). In this scenario, the sun would be 22 metres wide, about the size of a seven story building.
And UY Scuti would be 38 km wide – four times the height of Mt Everest.
www.space.com/41290-biggest-star.html
What Is the Biggest Star?
By Nola Taylor Redd | July 26, 2018
The radius of UY Scuti is about 1,700 times larger than the sun's radius.
(Image: © Philip Park)
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.
If UY Scuti replaced the sun in the center of the solar system, its photosphere would extend just beyond the orbit of Jupiter. The nebula of gas stripped from the star extends even farther out, beyond the orbit of Pluto to 400 times time the Earth-sun distance.
But UY Scuti doesn't remain stagnant. Scudder pointed out that the star varies in brightness as it varies in radius, with a margin of error of about 192 solar radii. These errors could allow other stars to beat out UY Scuti in the race for size. In fact, there are as many as 30 stars whose radii fit within UY Scuti's smallest estimated size, so it shouldn't sit too securely on its throne.
When speaking of bigness among stars, you have to define your terms. There are very heavy stars. And there are giganticstars, in terms of sheer physical size. The heaviest star is thought to be R136a1. It’s 265 times more massive than our sun – nearly twice as massive as what astronomers thought was possible. It’s the most massive star known at this time. But there are more ways than one to measure stars’ bigness. In terms of sheer physical size, the star UY Scuti is considered the biggest known. It’s only 30 times the sun’s mass, but has a radius more than 1,700 greater than the sun.
UY Scuti vs Earth – Let’s suppose the Earth is the size of a football (soccer, America). In this scenario, the sun would be 22 metres wide, about the size of a seven story building.
And UY Scuti would be 38 km wide – four times the height of Mt Everest.
www.space.com/41290-biggest-star.html