All We Know About the Stephenson 2 – 18 Star

With the first color deep space photograph taken by the James Webb Space Telescope, we once again realized that as humans, we are very small in this universe. For example, the Sun, which gives life to our Earth, seems huge to us and we cannot imagine anything bigger than it. But there is a star named Stephenson 2 – 18 in the same galaxy as us, which is thousands of times larger and hotter than the Sun, which we see huge.

Stephenson 2 – 18 is already the largest star ever discovered. Although it is thousands of light years away from us, we know a lot about it thanks to the space studies that accelerated with the development of technology. But we still don’t really know him, because he is far, far away. Let’s examine all the known facts about the star Stephenson 2 – 18 in detail and get to know this supergiant a little more closely.

First, what is Stephenson 2 – 18?

Before moving on to the known details, let’s define what Stephenson 2 – 18 is. Stephenson 2 – 18 is a red supergiant in the constellation Scutum and a member of the Stephenson 2 open cluster. Stephenson 2 – 18, which is thousands of times larger and much hotter than the Sun, is thousands of light-years away from our Earth.

Stephenson 2 – 18 vs Sun: How big is Stephenson 2 – 18 from the Sun?

How sure is the size of the Stephenson 2 – 18, everyone is very curious. Let’s think about it, if Stephenson 2 – 18 were where the Sun is, the space between Mercury, Venus, Earth, Mars and Jupiter would be completely covered by it. Because Stephenson 2 – 18 is exactly 2150 times larger than the Sun. In terms of volume, Stephenson 2 – 18 is exactly 10 billion times larger than the Sun.

Stephenson 2 – 18 biggest star?

Stephenson 2 – 18 is a red supergiant of spectral type M6. The magnitude of Stephenson 2 – 18 is defined as 2150 Sun radii. Considering that the Sun is about 700 thousand kilometers in diameter, calculate it. In this respect, Stephenson 2 – 18 is the largest star ever discovered. Of course, the universe is infinite, who knows how many bigger stars there are.

Previously, experts had discovered the stars MY Cephei in the constellation Cepheus, which is 2061 times the size of the Sun, and WY Velorum in the Vela constellation, which is 2028 times the size of the Sun, closest to the Stephenson 2 – 18 radius. Even earlier, the largest known stars were WOH G64 at 1540 Sun radius and UY Scuti at 1730 Sun radius. So every day we discover a bigger star.

When was Stephenson 2 – 18 discovered, what is known about it?

Stephenson 2 – Stephenson 2, which contains 18 stars, is one of the largest open clusters in the Milky Way Galaxy. This cluster was first discovered by the American astronomer Charles Bruce Stephenson in June 1990. The cluster emerged after a space deep infrared objective prism survey.

A 2007 study revealed that the Stephenson 2 cluster contains 26 red supergiants, the largest known population in the Milky Way Galaxy. The cluster is estimated to be about 17 million years old with plus or minus 3 million years. The Stephenson 2 cluster contains 20% of the known red supergiants in the galaxy. In another study conducted in 2023 on M-class supergiants in the cluster, maser emission was detected. This means that the two brightest stars with maser emission detected have a much higher mass loss rate than the others.

Another study revealed that the star Stephenson 2 – 18 has a radial velocity 20 km/s slower than the other stars in the cluster. Stephenson 2 – 18 is a red supergiant, but investigations have shown that its outer layers are changing and gradually turning into a bright blue color.

Where is Stephenson 2 – 18?

The distance between Stephenson 2 – 18, the largest star ever discovered, and our Earth is exactly 18900 light years. Stephenson 2 – 18; It is a member of the Stephenson 2 open cluster, located in the constellation Scutum. The Stephenson 2 open cluster covers 1.8 percent of the sky but is invisible because it is covered with dust. Visible with infrared lights, the Stephenson 2 cluster is located at the intersection of sky regions called Alpha and Beta Scuti.

Scutum constellation with Stephenson 2 – 18:

Stephenson 2 – The full name of the constellation Scutum, in which 18 red supergiants are located, is Scutum Sobiescianum. This name was given by the Polish astronomer Johannes Hevelius, who discovered it. When we examine the origins of the name, we see that this name was given to honor the Polish king of the period.

Scutum is one of the smallest and faintest constellations in the sky. Scutus, the 84th largest constellation, occupies only 109 square degrees of the sky. No star in the constellation Scutum makes it to the list of the 300 brightest stars in the sky.

The most popular members of the Scutum constellation are the white giant star Delta Scuti and the variable red supergiant UY Scuti. Other known members of the Scutum constellation are open clusters such as Messier 11, Messier 26 and Stephenson 2, called the Wild Duck Cluster.

Technical information about Stephenson 2 – 18:

• Spectral class M6
• apparent magnitude of 15.2631 ± 0.0092 G
• 7150 J apparent size
• 4698 H apparent size
• 2.9K apparent size
• 18900 light years, 5800 parsecs distance
• −0.0081 ± 0.3120 mas parallax
• RA: −3.045 ± 0.511 mas/year
• Range: -5.950 ± 0.480 mas/year suitable movement
• 440 thousand L (90 thousand – 630 thousand L) brightness
• 2150 R radius
• 3 million 200 thousand degrees temperature
• Location of the constellation Scutum
• 18h 39d 02. 3709099153s rise
• −06° 05′ 10.535778038″ deviation
• Names and designations: Stephenson 2-18, St2-18, Stephenson 2 DFK 1, Gaia DR2 4253084565963481856, MSX6C G026.1044-00.0283, IRAS 18363-0607, 2MASS J18390238-0605106

We have detailed all the known facts about Stephenson 2 – 18, the largest known star that is thousands of times larger and hotter than the Sun. Who knows, maybe as you read this, astronomers are discovering a new biggest star. You can share your thoughts in the comments.