3MM-1 (also known as COS-3mm-1) is a star-forming galaxy about 12.5 billion light-years away that is obscured by clouds of

dust Dust is made of particle size, fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian processes, aeolian process), Types of volcan ...

. It is located in the constellation of

Sextans Sextans is a faint, minor constellation on the celestial equator which was introduced in 1687 by Polish astronomer Johannes Hevelius. Its name is Latin for the astronomical sextant, an instrument that Hevelius made frequent use of in his obs ...

. It was first detected in spectroscopic data on rotational transitions of

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

obtained using the

Atacama Large Millimeter Array The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of 66 radio telescopes in the Atacama Desert of northern Chile, which observe electromagnetic radiation at millimeter and submillimeter wavelengths. The ar ...

from 23 to 24 December 2018, as detailed in an article that was published on 22 October 2019. The authors of this article described the discovery as " serendipitous", since the focus of their planned observations had been on galaxies at

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...

s near 1.5 that are quiescent — i.e. do not form stars — and directly observable, yet 3MM-1 was found at a redshift of about 5.5, is forming stars and not directly observable. In the same dataset, another dust-obscured star-forming galaxy, 3MM-2, was found at a redshift of about 3.3. In early 2021, a more precise estimate of 3MM-1's redshift was published, according to which the value is z = 5.857 ± 0.001. 3MM-1 has a

mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...

of about 10^10.8

solar mass The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxie ...

es, and stars form in it at about 100 times the rate as in the

Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...

References

Galaxies Sextans {{galaxy-stub