Stephenson 2-18 facts for kids
 Dense starfield around the red supergiant star St2-18 (brightest star in the image) as seen from the 2MASS astronomical survey. The picture was published in 2003. Credit: Université de Strasbourg/CNRS |
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| Observation data Epoch J2000 Equinox J2000 |
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|---|---|
| Constellation | Scutum |
| Right ascension | 18h 39m 02.3709s |
| Declination | -06° 05′ 10.5357″ |
| Characteristics | |
| Evolutionary stage | Red supergiant |
| Spectral type | ~M6 |
| Apparent magnitude (G) | 15.2631±0.0092 |
| Apparent magnitude (J) | 7.150 |
| Apparent magnitude (H) | 4.698 |
| Apparent magnitude (K) | 2.9 |
| Astrometry | |
| Proper motion (μ) | RA: −3.045±0.511 mas/yr Dec.: −5.950±0.480 mas/yr |
| Parallax (π) | −0.0081 ± 0.3120 mas |
| Distance | 19,560 ly (6,000 pc) |
| Details | |
| Radius | 2,150 R☉ |
| Luminosity | 90,000–440,000; 630,000 L☉ |
| Temperature | 3,200 K |
| Other designations | |
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Stephenson 2-18, Stephenson 2 DFK 1, RSGC2-18, 2MASS J18390238-0605106, IRAS 18363-0607
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| Database references | |
| SIMBAD | data |
Stephenson 2-18 (St2-18) is a truly enormous star. It is known as a red supergiant. This means it is one of the biggest and brightest types of stars in the universe.
This star is found in the Scutum constellation. It is very far away from Earth. Scientists estimate it is about 6,000 parsecs (or 20,000 light-years) from us.
How Big is Stephenson 2-18?
Stephenson 2-18 is one of the largest stars ever discovered. Imagine our Sun. Stephenson 2-18 has a radius 2,150 times bigger than the Sun's radius!
To give you an idea, its volume is more than 10 billion times larger than the Sun's. If Stephenson 2-18 were in our Solar System, it would stretch past the orbit of Saturn. It might even reach the orbit of Neptune!
What Makes It Special?
Stephenson 2-18 is not just huge; it's also incredibly bright. It is one of the most luminous (brightest) red supergiant stars we know.
It has a special color and temperature. Its spectral type is M6. This means it is a very cool star for its size, with a temperature of about 3,200 Kelvin. Our Sun, for comparison, is around 5,778 Kelvin.
Stephenson 2-18 is also thought to be part of a group of stars. This group is called the Stephenson 2 open cluster.
Images for kids
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Comparison of the sizes of selected different stars. From left to right are Cygnus OB2 #12, V382 Carinae, V915 Scorpii, UY Scuti and Stephenson 2-18. Orbits of Saturn and Neptune are also shown for comparison.
See also
In Spanish: Stephenson 2-18 para niños
