FSR 1758 is a large and bright but heavily obscured

globular cluster A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of memb ...

belonging to the

Milky Way galaxy 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 ey ...

. It is located at a distance of about 11.5 kpc from the Sun and about 3.7 kpc from the center of the galaxy. As FSR 1758 lies behind the

galactic bulge In astronomy, a galactic bulge (or simply bulge) is a tightly packed group of stars within a larger star formation. The term almost exclusively refers to the central group of stars found in most spiral galaxies (see galactic spheroid). Bulges ...

, it is heavily obscured by the foreground stars and dust. It was first noticed in 2007 in

2MASS The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, a ...

data and believed to be an open cluster, until data from the

Gaia mission ''Gaia'' is a space observatory of the European Space Agency (ESA), launched in 2013 and expected to operate until 2025. The spacecraft is designed for astrometry: measuring the positions, distances and motions of stars with unprecedented preci ...

revealed in 2018 that it is a globular cluster. The size and brightness of FSR 1758 may be comparable to or exceed that of the

Omega Centauri Omega Centauri (ω Cen, NGC 5139, or Caldwell 80) is a globular cluster in the constellation of Centaurus that was first identified as a non-stellar object by Edmond Halley in 1677. Located at a distance of , it is the largest-known globular clus ...

cluster, which is widely believed to be the nucleus of a dwarf galaxy that merged into Milky Way in the past. Therefore, FSR 1758 may be the nucleus of dwarf galaxy tentatively named Scorpius Dwarf galaxy. It may also be similar to another globular cluster,

Messier 54 Messier 54 (also known as M54 or NGC 6715) is a globular cluster in the constellation Sagittarius. It was discovered by Charles Messier in 1778 and then included in his catalog of comet-like objects. It is easily found in the sky, being close ...

, which is known to be the nucleus of

Sagittarius Dwarf Spheroidal Galaxy The Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph), also known as the Sagittarius Dwarf Elliptical Galaxy (Sgr dE or Sag DEG), is an elliptical loop-shaped satellite galaxy of the Milky Way. It contains four globular clusters ...

References

{{Sky, 17, 31, 12, -, 39, 48, 30, 87400 Globular clusters Scorpius