Your name is long: star 2MASS J20395358+4222505, but it is one of the brightest in our galaxy. It is located near the heart of the nearest massive star formation region, Cygnus-Xfor some 5,700 light years from the earth.
However, it is an unknown star. The reason for his near-anonymity is that he is behind dense clouds of gas and dust that reduce their visible light nearly 10,000 times before reaching us. In this way, what would intrinsically be a star of magnitude 4, visible to the naked eye (the eye reaches up to magnitude 6) is just another entry in the catalogs, a star of magnitude 14 (in astronomy, when a star is a smaller, brighter star is its magnitude).
Due to its peculiar characteristics, J20395358+4222505 was observed during the fine-tuning of the multi-object spectrograph MEGARA after installation on large canary telescope (GTC or Grantecan) located at the Roque de los Muchachos Observatory, on the Canary Island of La Palma).
The result, published in the journal Monthly notices from the Royal Astronomical Society, has been triply revealing to researchers.
First, the star turned out to be a powerful blue supergiant. With a mass nearly 50 times the mass of the Sun, a radius nearly 40 times that of the Sun and a luminosity approaching a million times that of the Sun, it is one of the most massive and luminous stars in the Milky Way.
Second, the star is located in a rare stage of evolution, reaching the end of its life in the main sequence (where stars spend 90% of their lives) and about to undergo major changes that will transform it. The researchers believe the star is likely to become a blue hypergiant, of which very few are known in the Milky Way.
your strange speed
The third and most unexpected surprise is that the star appears vary your speed a lot. Two observations made on consecutive days show a change in the star’s speed of up to 60 km/s. Such a high velocity, in such a massive star, implies an enormous gravitational influence that forces it to move so quickly.
The researchers shuffle two possible explanations: a comparable star or a compact object (neutron star or black hole) as companions in a Binary System. However, the observations show no sign of a companion star, which further narrows the options. Had it been a compact object, the parent star would have been one of the most massive in our galaxy.
“At the moment, we have already discovered that it is a blue colossus hidden behind a wall of interstellar gas and dust, astronomically, in the garden of our house”, he explains. Artemio Smithprofessor at the University of La Laguna (ULL) and researcher at the IAC who directed the study.
“Further observations are needed to unravel the true nature of J20395358+4222505, whose history, both past and future, makes it one of the most peculiar objects in the galaxy,” he adds. Sara Rodriguez Berlanas, researcher at the University of Alicante, PhD student at IAC/ULL and co-author of the article. The new observations should confirm the velocity changes and allow a possible orbit to be determined.
For Armando Gil de Pazastrophysicist at the Universidad Complutense de Madrid (UCM) and principal investigator of the MEGARA instrument, “this project demonstrates that the detailed spectroscopic information provided by instruments such as MEGARA, together with large telescopes such as the GTC, are essential to unravel many of the mysteries that objects as irrelevant as J20395358+4222505 hide”.
In addition to the IAC, the ULL and the UCM, the European Southern Observatory (ESO), the Center for Astrobiology (CAB), the University of Munich, the University of Innsbruck, the UCM and the company Fractal participated in this study.