Using astrometric, photometric and optical spectroscopy data from ESA’s Gaia mission and the 2MASS survey, astronomers have discovered a large, populous, young open cluster in the constellation of Scutum.
This image shows Valparaiso 1, a young open cluster located 7,500 light-years away in the constellation of Scutum. Image credit: Gabriel Pérez Díaz, SMM & IAC.
Open clusters are large collections of stars weakly bound by the shackles of gravity, all of which formed from the same molecular cloud.
Because of this, all the stars have the same composition and age, but vary in their mass because they formed at different positions within the cloud.
This unique property gives astronomers a cosmic laboratory in which to study the formation and evolution of stars — a process that is thought to depend strongly on a star’s mass.
The newly-discovered open cluster resides approximately 7,500 light-years away in the constellation of Scutum.
Named Valparaiso 1, the cluster belongs to the Sagittarius arm of our Milky Way Galaxy.
It is about 75 million years old, and contains at least 15,000 stars.
Ten luminous bright giant or supergiant stars are members of the cluster, including the well-known Cepheid CM Sct.
“Unlike in younger clusters, the bright evolved members of Valparaiso 1 do not stand out at all over their neighbors,” said Dr. Ignacio Negueruela, an astronomer at the University of Alicante.
“Although they are among the brightest stars in the field, there are several dozen stars of comparable (or higher) brightness with similar colors.”
The core of Valparaiso 1 is comparable in size and mass to the most massive open clusters in the Solar neighborhood.
“Previous searches tried to locate open clusters, but Valparaiso 1 does not look like a cluster similar to those which we usually find, and that is why it was not discovered before,” said Dr. Ricardo Dorda, an astronomer at the University of Alicante, the Instituto de Astrofísica de Canarias, and the University of La Laguna.
The discovery is reported in a paper in the Monthly Notices of the Royal Astronomical Society.
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I. Negueruela et al. A massive open cluster hiding in full sight. MNRAS, published online April 24, 2021; doi: 10.1093/mnras/stab1117
