UY Scuti, the largest star in the universe, has a radius that is 1,700 times larger than our sun's. Such a star is also able to undergo Nuclear Fusion of much denser and heavier objects. In other words, it is able to produce a LOT more energy than our sun.In addition to that, UY Scuti is also 340,000 times more luminous than our sun. It is still incredibly easy to see despite being many thousands of light years away.Fun fact, UY Scuti also has a circumference of 4.7 billion miles. To put that in perspective, the sun's circumference is 2.7 million miles.&nbsp;That is one very big star.

What is the Biggest Star in the Universe?

UY Scuti (BD-12°5055) is a <a href="https://en.wikipedia.org/wiki/Red_supergiant" title="Red supergiant" dir="ltr">red supergiant</a> <a href="https://en.wikipedia.org/wiki/Star" title="Star" dir="ltr">star</a> in the <a href="https://en.wikipedia.org/wiki/Constellation" title="Constellation" dir="ltr">constellation</a> <a href="https://en.wikipedia.org/wiki/Scutum_(constellation)" title="Scutum (constellation)" dir="ltr">Scutum</a>. It is considered one of the <a href="https://en.wikipedia.org/wiki/List_of_largest_stars" title="List of largest stars" dir="ltr">largest known stars</a> by radius and is also a <a href="https://en.wikipedia.org/wiki/Pulsating_variable_star" title="Pulsating variable star" dir="ltr">pulsating variable star</a>, with a maximum brightness of <a href="https://en.wikipedia.org/wiki/Apparent_magnitude" title="Apparent magnitude" dir="ltr">magnitude</a> 8.29 and a minimum of magnitude 10.56. It has an estimated radius of 1,708 <a href="https://en.wikipedia.org/wiki/Solar_radius" title="Solar radius" dir="ltr">solar radii</a> (1.188×109 <a href="https://en.wikipedia.org/wiki/Kilometre" title="Kilometre" dir="ltr">kilometres</a>; 7.94 <a href="https://en.wikipedia.org/wiki/Astronomical_unit" title="Astronomical unit" dir="ltr">astronomical units</a>), thus a volume nearly 5 billion times that of the Sun. It is approximately 2.9 <a href="https://en.wikipedia.org/wiki/Parsec#Parsecs_and_kiloparsecs" title="Parsec" dir="ltr">kiloparsecs</a> (9,500 <a href="https://en.wikipedia.org/wiki/Light-year" title="Light-year" dir="ltr">light-years</a>) from <a href="https://en.wikipedia.org/wiki/Earth" title="Earth" dir="ltr">Earth</a>. If placed at the center of the <a href="https://en.wikipedia.org/wiki/Solar_System" title="Solar System" dir="ltr">Solar System</a>, its <a href="https://en.wikipedia.org/wiki/Photosphere" title="Photosphere" dir="ltr">photosphere</a> would at least engulf the orbit of <a href="https://en.wikipedia.org/wiki/Jupiter" title="Jupiter" dir="ltr">Jupiter</a>.
<h2>Contents</h2><h2>Nomenclature and history</h2>UY Scuti was first catalogued in 1860 by German astronomers at the <a href="https://en.wikipedia.org/wiki/Friedrich_Wilhelm_Argelander" title="Friedrich Wilhelm Argelander" dir="ltr">Bonn Observatory</a>, who were completing a survey of stars for the <a href="https://en.wikipedia.org/wiki/Durchmusterung" title="Durchmusterung" dir="ltr">Bonner Durchmusterung Stellar Catalogue</a>.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-Universe_Guide-10" dir="ltr">[10]</a> It was designated BD-12°5055, the 5,055th star between 12°S and 13°S counting from 0h <a href="https://en.wikipedia.org/wiki/Right_ascension" title="Right ascension" dir="ltr">right ascension</a>.
On detection in the second survey, the star was found to have changed slightly in brightness, suggesting that it was a new <a href="https://en.wikipedia.org/wiki/Variable_star" title="Variable star" dir="ltr">variable star</a>. In accordance with the international standard for <a href="https://en.wikipedia.org/wiki/Variable_star_designation" title="Variable star designation" dir="ltr">designation of variable stars</a>, it was called UY Scuti, denoting it as the 38th variable star of the constellation Scutum.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-11" dir="ltr">[11]</a>
UY Scuti is located a few degrees north of the <a href="https://en.wikipedia.org/wiki/Stellar_classification#Class_A" title="Stellar classification" dir="ltr">A-type</a> star <a href="https://en.wikipedia.org/wiki/Gamma_Scuti" title="Gamma Scuti" dir="ltr">Gamma Scuti</a> and northeast of the <a href="https://en.wikipedia.org/wiki/Eagle_Nebula" title="Eagle Nebula" dir="ltr">Eagle Nebula</a>. Although the star is very luminous, it is, at its brightest, only 9th magnitude as viewed from Earth, due to its distance and location in the <a href="https://en.wikipedia.org/wiki/Zone_of_Avoidance" title="Zone of Avoidance" dir="ltr">Zone of Avoidance</a> within the <a href="https://en.wikipedia.org/wiki/Great_Rift_(astronomy)" title="Great Rift (astronomy)" dir="ltr">Cygnus rift</a>.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-12" dir="ltr">[12]</a>
<h2>Characteristics</h2><img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/UY_Scuti_size_comparison_to_the_sun.png/220px-UY_Scuti_size_comparison_to_the_sun.png" width="220" height="287" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/UY_Scuti_size_comparison_to_the_sun.png/330px-UY_Scuti_size_comparison_to_the_sun.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/UY_Scuti_size_comparison_to_the_sun.png/440px-UY_Scuti_size_comparison_to_the_sun.png 2x"><div class="caption" dir="ltr">An illustration of the approximate size of UY Scuti compared to the <a href="https://en.wikipedia.org/wiki/Sun" title="Sun" dir="ltr">Sun</a></div><img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/41/Comparison_of_planets_and_stars_%282017_update%29.png/300px-Comparison_of_planets_and_stars_%282017_update%29.png" width="300" height="197" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/4/41/Comparison_of_planets_and_stars_%282017_update%29.png/450px-Comparison_of_planets_and_stars_%282017_update%29.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/4/41/Comparison_of_planets_and_stars_%282017_update%29.png/600px-Comparison_of_planets_and_stars_%282017_update%29.png 2x">UY Sct is a dust-enshrouded bright red supergiant<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-vanloon-13" dir="ltr">[13]</a> and is classified as a semiregular variable with an approximate pulsation period of 740 days.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-gcvs-5" dir="ltr">[5]</a><a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-aavso-14" dir="ltr">[14]</a><a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-jura-15" dir="ltr">[15]</a>
In the summer of 2012, <a href="https://en.wikipedia.org/wiki/AMBER_(Very_Large_Telescope)" title="AMBER (Very Large Telescope)" dir="ltr">AMBER</a> <a href="https://en.wikipedia.org/wiki/Interferometry" title="Interferometry" dir="ltr">interferometry</a> with the <a href="https://en.wikipedia.org/wiki/Very_Large_Telescope" title="Very Large Telescope" dir="ltr">Very Large Telescope</a> (VLT) in the <a href="https://en.wikipedia.org/wiki/Atacama_Desert" title="Atacama Desert" dir="ltr">Atacama Desert</a> in <a href="https://en.wikipedia.org/wiki/Chile" title="Chile" dir="ltr">Chile</a> was used to measure the parameters of three red supergiants near the <a href="https://en.wikipedia.org/wiki/Galactic_Center" title="Galactic Center" dir="ltr">Galactic Center</a> region:<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-Torres2013-3" dir="ltr">[3]</a> UY Scuti, <a href="https://en.wikipedia.org/wiki/AH_Scorpii" title="AH Scorpii" dir="ltr">AH Scorpii</a>, and <a href="https://en.wikipedia.org/wiki/KW_Sagittarii" title="KW Sagittarii" dir="ltr">KW Sagittarii</a>. They determined that all three stars are over 1,000 times bigger than the <a href="https://en.wikipedia.org/wiki/Sun" title="Sun" dir="ltr">Sun</a> and over 100,000 times more luminous than the Sun. The stars' sizes were calculated using the <a href="https://en.wikipedia.org/wiki/Opacity_(optics)" title="Opacity (optics)" dir="ltr">Rosseland radius</a>, the location at which the <a href="https://en.wikipedia.org/wiki/Optical_depth" title="Optical depth" dir="ltr">optical depth</a> is 2⁄3,<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-opacity-16" dir="ltr">[16]</a> with distances adopted from earlier publications. UY Scuti was found to be the largest and the most luminous of the three stars measured, at 1,708&nbsp;±&nbsp;192&nbsp;<a href="https://en.wikipedia.org/wiki/Solar_radius" title="Solar radius" dir="ltr">R☉</a> (1.188×109&nbsp;±&nbsp;134,000,000&nbsp;<a href="https://en.wikipedia.org/wiki/Kilometre" title="Kilometre" dir="ltr">km</a>; 7.94&nbsp;±&nbsp;0.89&nbsp;<a href="https://en.wikipedia.org/wiki/Astronomical_unit" title="Astronomical unit" dir="ltr">AU</a>) based on an <a href="https://en.wikipedia.org/wiki/Angular_diameter" title="Angular diameter" dir="ltr">angular diameter</a> of 5.48±0.10&nbsp;<a href="https://en.wikipedia.org/wiki/Milliarcsecond" title="Milliarcsecond" dir="ltr">mas</a> and an assumed distance of 2.9±0.317&nbsp;<a href="https://en.wikipedia.org/wiki/Kiloparsecs" title="Kiloparsecs" dir="ltr">kiloparsecs</a> (kpc) (about 9,500±1,030&nbsp;light-years) which was originally derived in 1970 based on the modelling of the spectrum of UY Sct.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-lee-9" dir="ltr">[9]</a> The luminosity is then calculated to be 340,000&nbsp;<a href="https://en.wikipedia.org/wiki/Solar_luminosity" title="Solar luminosity" dir="ltr"><var dir="ltr">L</var>☉</a> at an effective temperature of 3,365 ± 134 <a href="https://en.wikipedia.org/wiki/Kelvin" title="Kelvin" dir="ltr">K</a>, giving an initial mass of 25&nbsp;<var dir="ltr">M</var>☉ (possibly up to 40&nbsp;<var dir="ltr">M</var>☉ for a non-rotating star).<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-Torres2013-3" dir="ltr">[3]</a>
A hypothetical object travelling at the <a href="https://en.wikipedia.org/wiki/Speed_of_light" title="Speed of light" dir="ltr">speed of light</a> would be observed to take about seven hours to travel along UY Scuti's <a href="https://en.wikipedia.org/wiki/Great_circle" title="Great circle" dir="ltr">great circle</a> whereas it would take 14.5 seconds to circle the Sun.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-17" dir="ltr">[17]</a>
Direct measurements of parallax of UY Sct by the <a href="https://en.wikipedia.org/wiki/Gaia_Data_Release_2" title="Gaia Data Release 2" dir="ltr">Gaia Data Release 2</a> have recently given a parallax of 0.6433±0.1059&nbsp;mas, yielding a much shorter distance of approximately 1.55 kiloparsecs (5,100&nbsp;ly),<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-dr2-18" dir="ltr">[18]</a> and consequently much lower luminosity and radius values of around 86,300–87,100&nbsp;<var dir="ltr">L</var>☉ and 755&nbsp;<var dir="ltr">R</var>☉ respectively.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-messineo2019-19" dir="ltr">[19]</a> However, the Gaia parallax might be unreliable, at least until further observations, due to a very high level of astrometric noise.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-gaia-6" dir="ltr">[6]</a>
UY Scuti's mass is uncertain, primarily because it has no visible companion star by which its mass can be measured through gravitational interference. However, it is expected to be between 7 and 10&nbsp;<var dir="ltr">M</var>☉.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-Torres2013-3" dir="ltr">[3]</a> Mass is being lost at 5.8×10−5&nbsp;<var dir="ltr">M</var>☉ per year, leading to an extensive and complex circumstellar environment of gas and dust.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-sylvester-20" dir="ltr">[20]</a>
<h2>Supernova</h2>Based on current models of <a href="https://en.wikipedia.org/wiki/Stellar_evolution" title="Stellar evolution" dir="ltr">stellar evolution</a>, UY Scuti has begun to fuse <a href="https://en.wikipedia.org/wiki/Helium" title="Helium" dir="ltr">helium</a>, and continues to fuse hydrogen in a shell around the core. The location of UY Scuti deep within the Milky Way disc suggests that it is a <a href="https://en.wikipedia.org/wiki/Metallicity" title="Metallicity" dir="ltr">metal-rich</a> star.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-21" dir="ltr">[21]</a>
After fusing heavy elements, its core will begin to produce iron, disrupting the balance of gravity and radiation in its core and resulting in a <a href="https://en.wikipedia.org/wiki/Supernova" title="Supernova" dir="ltr">core collapse supernova</a>. It is expected that stars like UY Scuti should evolve back to hotter temperatures to become a <a href="https://en.wikipedia.org/wiki/Yellow_hypergiant" title="Yellow hypergiant" dir="ltr">yellow hypergiant</a>, <a href="https://en.wikipedia.org/wiki/Luminous_blue_variable" title="Luminous blue variable" dir="ltr">luminous blue variable</a>, or a <a href="https://en.wikipedia.org/wiki/Wolf%E2%80%93Rayet_star" title="Wolf–Rayet star" dir="ltr">Wolf–Rayet star</a>, creating a strong stellar wind that will eject its outer layers and expose the core, before exploding as a type <a href="https://en.wikipedia.org/wiki/Type_II_supernova#Type_IIb_supernovae" title="Type II supernova" dir="ltr">IIb</a>, <a href="https://en.wikipedia.org/wiki/Type_II_supernova#Type_IIn_supernovae" title="Type II supernova" dir="ltr">IIn</a>, or type <a href="https://en.wikipedia.org/wiki/Type_Ib_and_Ic_supernovae" title="Type Ib and Ic supernovae" dir="ltr">Ib/Ic</a> supernova.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-groh-22" dir="ltr">[22]</a>
<h2>See also</h2><UL><LI><a href="https://en.wikipedia.org/wiki/R136a1" title="R136a1" dir="ltr">R136a1</a> – one of the most massive and luminous stars known.</LI><LI><a href="https://en.wikipedia.org/wiki/Stephenson_2-18" title="Stephenson 2-18" dir="ltr">Stephenson 2-18</a> – one of the largest known stars, having an estimated radius of approximately 2,150 solar radii.</LI></UL><OL><LI>^ </LI></OL>

scienceandnature

Science & Nature

UY Scuti (BD-12°5055 ) is a <a href="https://en.wikipedia.org/wiki/Red_supergiant">red supergiant </a><a href="https://en.wikipedia.org/wiki/Star">star </a>in the <a href="https://en.wikipedia.org/wiki/Constellation">constellation </a><a href="https://en.wikipedia.org/wiki/Scutum_(constellation)">Scutum </a>. It is considered one of the <a href="https://en.wikipedia.org/wiki/List_of_largest_stars">largest known stars </a>by radius and is also a <a href="https://en.wikipedia.org/wiki/Pulsating_variable_star">pulsating variable star </a>, with a maximum brightness of <a href="https://en.wikipedia.org/wiki/Apparent_magnitude">magnitude </a>8.29 and a minimum of magnitude 10.56. It has an estimated radius of 1,708 <a href="https://en.wikipedia.org/wiki/Solar_radius">solar radii </a>(1.188× 109 <a href="https://en.wikipedia.org/wiki/Kilometre">kilometres </a>; 7.94 <a href="https://en.wikipedia.org/wiki/Astronomical_unit">astronomical units </a>), thus a volume nearly 5 billion times that of the Sun. It is approximately 2.9 <a href="https://en.wikipedia.org/wiki/Parsec#Parsecs_and_kiloparsecs">kiloparsecs </a>(9,500 <a href="https://en.wikipedia.org/wiki/Light-year">light-years </a>) from <a href="https://en.wikipedia.org/wiki/Earth">Earth </a>. If placed at the center of the <a href="https://en.wikipedia.org/wiki/Solar_System">Solar System </a>, its <a href="https://en.wikipedia.org/wiki/Photosphere">photosphere </a>would at least engulf the orbit of <a href="https://en.wikipedia.org/wiki/Jupiter">Jupiter </a>.

UY Scuti was first catalogued in 1860 by German astronomers at the <a href="https://en.wikipedia.org/wiki/Friedrich_Wilhelm_Argelander">Bonn Observatory </a>, who were completing a survey of stars for the <a href="https://en.wikipedia.org/wiki/Durchmusterung">Bonner Durchmusterung Stellar Catalogue </a> .<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-Universe_Guide-10">[10] </a> It was designated BD-12°5055, the 5,055th star between 12°S and 13°S counting from 0h <a href="https://en.wikipedia.org/wiki/Right_ascension">right ascension </a>.

On detection in the second survey, the star was found to have changed slightly in brightness, suggesting that it was a new <a href="https://en.wikipedia.org/wiki/Variable_star">variable star </a>. In accordance with the international standard for <a href="https://en.wikipedia.org/wiki/Variable_star_designation">designation of variable stars </a>, it was called UY Scuti, denoting it as the 38th variable star of the constellation Scutum.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-11">[11] </a>

UY Scuti is located a few degrees north of the <a href="https://en.wikipedia.org/wiki/Stellar_classification#Class_A">A-type </a>star <a href="https://en.wikipedia.org/wiki/Gamma_Scuti">Gamma Scuti </a>and northeast of the <a href="https://en.wikipedia.org/wiki/Eagle_Nebula">Eagle Nebula </a>. Although the star is very luminous, it is, at its brightest, only 9th magnitude as viewed from Earth, due to its distance and location in the <a href="https://en.wikipedia.org/wiki/Zone_of_Avoidance">Zone of Avoidance </a>within the <a href="https://en.wikipedia.org/wiki/Great_Rift_(astronomy)">Cygnus rift </a>.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-12">[12] </a>

UY Sct is a dust-enshrouded bright red supergiant<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-vanloon-13">[13] </a> and is classified as a semiregular variable with an approximate pulsation period of 740 days.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-gcvs-5">[5] </a> <a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-aavso-14">[14] </a> <a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-jura-15">[15] </a>

In the summer of 2012, <a href="https://en.wikipedia.org/wiki/AMBER_(Very_Large_Telescope)">AMBER </a><a href="https://en.wikipedia.org/wiki/Interferometry">interferometry </a>with the <a href="https://en.wikipedia.org/wiki/Very_Large_Telescope">Very Large Telescope </a>(VLT) in the <a href="https://en.wikipedia.org/wiki/Atacama_Desert">Atacama Desert </a>in <a href="https://en.wikipedia.org/wiki/Chile">Chile </a>was used to measure the parameters of three red supergiants near the <a href="https://en.wikipedia.org/wiki/Galactic_Center">Galactic Center </a>region:<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-Torres2013-3">[3] </a> UY Scuti, <a href="https://en.wikipedia.org/wiki/AH_Scorpii">AH Scorpii </a>, and <a href="https://en.wikipedia.org/wiki/KW_Sagittarii">KW Sagittarii </a>. They determined that all three stars are over 1,000 times bigger than the <a href="https://en.wikipedia.org/wiki/Sun">Sun </a>and over 100,000 times more luminous than the Sun. The stars' sizes were calculated using the <a href="https://en.wikipedia.org/wiki/Opacity_(optics)">Rosseland radius </a>, the location at which the <a href="https://en.wikipedia.org/wiki/Optical_depth">optical depth </a>is 2 ⁄3 ,<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-opacity-16">[16] </a> with distances adopted from earlier publications. UY Scuti was found to be the largest and the most luminous of the three stars measured, at 1,708 ± 192 <a href="https://en.wikipedia.org/wiki/Solar_radius">R ☉ </a>(1.188× 109  ± 134,000,000 <a href="https://en.wikipedia.org/wiki/Kilometre">km </a>; 7.94 ± 0.89 <a href="https://en.wikipedia.org/wiki/Astronomical_unit">AU </a>) based on an <a href="https://en.wikipedia.org/wiki/Angular_diameter">angular diameter </a>of 5.48± 0.10 <a href="https://en.wikipedia.org/wiki/Milliarcsecond">mas </a> and an assumed distance of 2.9± 0.317 <a href="https://en.wikipedia.org/wiki/Kiloparsecs">kiloparsecs </a> (kpc) (about 9,500± 1,030 light-years ) which was originally derived in 1970 based on the modelling of the spectrum of UY Sct.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-lee-9">[9] </a> The luminosity is then calculated to be 340,000 <a href="https://en.wikipedia.org/wiki/Solar_luminosity">L ☉ </a>at an effective temperature of 3,365 ± 134 <a href="https://en.wikipedia.org/wiki/Kelvin">K </a>, giving an initial mass of 25 M ☉ (possibly up to 40 M ☉ for a non-rotating star).<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-Torres2013-3">[3] </a>

A hypothetical object travelling at the <a href="https://en.wikipedia.org/wiki/Speed_of_light">speed of light </a>would be observed to take about seven hours to travel along UY Scuti's <a href="https://en.wikipedia.org/wiki/Great_circle">great circle </a>whereas it would take 14.5 seconds to circle the Sun.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-17">[17] </a>

Direct measurements of parallax of UY Sct by the <a href="https://en.wikipedia.org/wiki/Gaia_Data_Release_2">Gaia Data Release 2 </a>have recently given a parallax of 0.6433± 0.1059 mas , yielding a much shorter distance of approximately 1.55 kiloparsecs (5,100 ly),<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-dr2-18">[18] </a> and consequently much lower luminosity and radius values of around 86,300–87,100 L ☉ and 755 R ☉ respectively.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-messineo2019-19">[19] </a> However, the Gaia parallax might be unreliable, at least until further observations, due to a very high level of astrometric noise.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-gaia-6">[6] </a>

UY Scuti's mass is uncertain, primarily because it has no visible companion star by which its mass can be measured through gravitational interference. However, it is expected to be between 7 and 10 M ☉ .<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-Torres2013-3">[3] </a> Mass is being lost at 5.8× 10−5  M ☉ per year, leading to an extensive and complex circumstellar environment of gas and dust.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-sylvester-20">[20] </a>

Based on current models of <a href="https://en.wikipedia.org/wiki/Stellar_evolution">stellar evolution </a>, UY Scuti has begun to fuse <a href="https://en.wikipedia.org/wiki/Helium">helium </a>, and continues to fuse hydrogen in a shell around the core. The location of UY Scuti deep within the Milky Way disc suggests that it is a <a href="https://en.wikipedia.org/wiki/Metallicity">metal-rich </a>star.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-21">[21] </a>

After fusing heavy elements, its core will begin to produce iron, disrupting the balance of gravity and radiation in its core and resulting in a <a href="https://en.wikipedia.org/wiki/Supernova">core collapse supernova </a>. It is expected that stars like UY Scuti should evolve back to hotter temperatures to become a <a href="https://en.wikipedia.org/wiki/Yellow_hypergiant">yellow hypergiant </a>, <a href="https://en.wikipedia.org/wiki/Luminous_blue_variable">luminous blue variable </a>, or a <a href="https://en.wikipedia.org/wiki/Wolf%E2%80%93Rayet_star">Wolf–Rayet star </a>, creating a strong stellar wind that will eject its outer layers and expose the core, before exploding as a type <a href="https://en.wikipedia.org/wiki/Type_II_supernova#Type_IIb_supernovae">IIb </a>, <a href="https://en.wikipedia.org/wiki/Type_II_supernova#Type_IIn_supernovae">IIn </a>, or type <a href="https://en.wikipedia.org/wiki/Type_Ib_and_Ic_supernovae">Ib/Ic </a>supernova.<a href="https://en.wikipedia.org/wiki/UY_Scuti#cite_note-groh-22">[22] </a>

<ul><li><a href="https://en.wikipedia.org/wiki/R136a1">R136a1 </a>– one of the most massive and luminous stars known. </li><li><a href="https://en.wikipedia.org/wiki/Stephenson_2-18">Stephenson 2-18 </a>– one of the largest known stars, having an estimated radius of approximately 2,150 solar radii. </li> </ul>

UY Scuti

What is the Biggest Star in the Universe?

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