In terms of star size, the Sun is only average, about half of the known stars are larger than the Sun, the other half are smaller. The largest star ever discovered in the universe is UY Scuti – A Super star-super giant with a radius 1708 times larger than the Sun. However, UY Scuti’s top position is not solid at all.
In 1860, UY Scuti was first cataloged by German astronomers at the Bonn Observatory under the number BD – 12 5055.. When they observed it a second time, they found that it grew brighter and then faded again over the course of 740 days. It is because of this feature that astronomers consider it a variable star. UY Scuti is located near the center of the Milky Way, about 9500 light years away.
Size correlation of the stars Sun, Sirius, Pollux, Arcturus and UY Scuti. Source: Onedio
Located in the constellation Scutum (the Shield), UY Scuti is a super supergiant star (hypergiant), a larger type of star super giant star (supergiant), and of course larger giant star (giant) a lot. Supergiant stars are rare bright stars. They lose a lot of mass due to the dispersion of high-speed stellar winds.
Of course, the size of each star is an estimate, based on measurements taken at very long distances. The star’s radius is calculated as the distance from the center to the photosphere, the region considered the star’s surface because from which photons leave the star to enter the universe. The radius of the Sun is about 695700 km, this number is called 1 solar rays (R☉).
If UY Scuti were to move the center of the Sun in the solar system, its photosphere would exceed the orbit of Jupiter. The gas escaping from UY Scuti even extends beyond the orbit of Pluto, 400 times further than the distance from the Sun to Earth.
Size correlation of celestial bodies in the solar system and some stars. Source: Wikipedia
The size of UY Scuti has not yet been precisely determined. Scientists show that the brightness of this star will change because its radius is calculated differently, with a margin of error of about 192 R☉. This difference puts UY Scuti at risk of being “usurped” by other stars in the race for size. In fact, there are up to 30 stars with a radius equal to UY Scuti’s estimated minimum size, so this star’s “largest star” title is still in play.
Also, UY Scuti’s huge radius wasn’t enough to make one why is it the heaviest?this honor goes to R136a1, about 300 times more massive than the Sun, but only 30 times larger in radius. Meanwhile, the mass of UY Scuti is only 30 times that of the Sun.
From left to right: size correlation of red dwarfs, suns, B main sequences and R136a1. Source: ESO
CANDIDATE FOR “THE GREATEST STAR”
So which star will “usurp” UY Scuti if its size does not reach 1708 times the radius of the Sun? The following “good candidates” can be mentioned:
- WHO G64, with dimensions 1504 -1730 R☉, is a supergiant star located in the Large Magellanic Cloud. Like UY Scuti, the brightness of the OMS G64 has also not been precisely determined. Its radius is estimated to be up to 3000 R☉. Why is there such a big difference? partly because the presence of dust affected the calculation of brightness and radius.
Location of WOH G64 in the Large Magellanic Cloud. Source: Universe Today
- RW Cephei has dimensions equal to 1535 CHEAP. This star is an orange supergiant in the constellation Cepheus, which is also a variable star.
- Westerland 1-26 sizes range from 1530 to 2550 R. With the above data, assuming that this star replaces the position of the Sun, its photosphere could “overwhelm” Saturn’s orbit. Unlike other stars, Westerlund 1-26 has a change in temperature, but the brightness remains the same.
- KY Cygni, is a red supergiant located in the constellation Swan (Swan), with sizes ranging from 1420 to 2850 CHEAP. The larger estimate above is considered ambiguous by astronomers, while the smaller estimate is consistent with other stars studied. in the same investigation, as well as with the theoretical model of stellar evolution.
Simulation of the size correlation between the Sun and the star VY Canis Majoris. Source: Wikipedia
- VY Canis Mayoris sizes between 1300 and 1504 CHEAP. Previously, estimates of the size of this red supergiant ranged from 1800 to 2200 R☉, but these data contradict the theory of stellar evolution. Recent results turn out to be consistent, although some sources still consider it the largest star.
The universe is vast, the number of stars in a single galaxy like our Milky Way has reached hundreds of billions, so sooner or later the stars considered the largest today will also be replaced by larger stars. Our job is to wait for the latest research reports from scientists.
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