RSGC3 (''Red Supergiant Cluster 3'') is a young massive

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, an ...

belonging to the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...

galaxy. It was discovered in 2010 in the GLIMPSE survey data. The cluster is located in the constellation

Scutum The ''scutum'' (; plural ''scuta'') was a type of shield used among Italic peoples in antiquity, most notably by the army of ancient Rome starting about the fourth century BC. The Romans adopted it when they switched from the military formati ...

at the distance of about 7 kpc from the Sun. It is likely situated at the intersection of the northern end of the Long Bar of the Milky Way and the inner portion of the

Scutum–Centaurus Arm The Scutum–Centaurus Arm, also known as Scutum-Crux arm, is a long, diffuse curving streamer of stars, gas and dust that spirals outward from the proximate end of the Milky Way's central bar. The Milky Way has been posited since the 1950s to ...

—one of its two major spiral arms. The age of RSGC3 is estimated at 18–24 million years. The 16 detected

red supergiant Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Ant ...

cluster members with masses of about are

type II supernova A Type II supernova (plural: ''supernovae'' or ''supernovas'') results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, but no more than 40 to 50 times, the mass of the Sun () to undergo th ...

progenitors. The cluster is heavily obscured and has not been detected in the

visible light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...

. It lies close to other groupings of red supergiants known as

RSGC1 RSGC1 (''Red Supergiant Cluster 1'') is a young massive open cluster in the Milky Way galaxy. It was discovered in 2006 in the data generated by several infrared surveys, named for the unprecedented number of red supergiant members. The cluster ...

, Stephenson 2, Alicante 7, Alicante 8, and Alicante 10. The total mass of RSGC3 is estimated at 20 thousand solar masses, which makes it one of the most massive open clusters in the Galaxy. More work has identified a population of at least 30 additional red supergiants in the vicinity of RSGC3, 7 of which are tightly grouped and have been assumed to form a cluster named Alicante 7. The number of red supergiants identified in the several small areas studied in this region of the sky forms a significant fraction of all those known in the galaxy, suggesting very unusual properties for the region near the end of the galactic bar.

References

{{DEFAULTSORT:RSGC3 RSGC3 Scutum (constellation) Scutum–Centaurus Arm