An article published in the journal “Astronomy & Astrophysics” describes the discovery of a twin star of the Sun. It’s HD 186302, studied by a team of researchers led by Vardan Adibekyan of the Instituto de Astrofísica and Ciências do Espaço (IA), in Portugal, starting from the data collected by the AMBRE project that collected about 230,000 star spectra, along with other data collected by ESA’s Gaia space probe. HD 186302 is really similar to the Sun not only as an age and chemical composition but also in mass and size and this offers hopes that it has planets similar to the Earth.
About 184 light years away from Earth, the star HD 186302 was probably born in the same nursery of the Sun and who knows how many other stars born in the same cluster. In the course of over 4.5 billion years, they moved away so today it’s difficult to reconstruct the history of this cosmic family. AMBRE was defined as a galactic archeology project created from the collaboration between ESO and the Côte d’Azur Observatory to determine the atmospheric parameters of the stellar spectra in the archives of ESO’s FEROS, HARPS, UVES and GIRAFFE spectrographs.
The researchers made a series of selections between 17,000 stars in the AMBRE project archive based on their characteristics, from age to chemical composition. The first selection, also based on the Gaia’s mission Data Release 2, reduced the candidates to 55 and each parameter allowed to shrink the group to get very few stars of which the researchers tried to reconstruct the movements in the course of their lives to see if they formed in the same cluster as the Sun.
In the end, HD 186302 was found to be the star that has the characteristics with the highest compatibility with those of a Sun’s sibling. Other candidates show interesting characteristics but also greater differences with the Sun in terms of atmospheric parameters and chemical composition compared to HD 186302.
In May 2014, the announcement of the identification of the star HD 162826 as Sun’s sibling arrived. HD 186302 is even more similar to the Sun in size and mass so it was defined as its twin. Discovering the Sun’s siblings is important because it offers more information about its birth and the possibility that they have planets, with all the consequences that this entails.
Vardan Adibekyan mentioned the chance that in the period called the Late Heavy Bombardment, about 4 billion years ago, early life forms spread among different solar systems, since at that time they were much closer than today. In essence, not only those stars were born together with the Sun but there’s also the chance that they host some Earth’s sibling life forms.
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I think that astronomy my well be the fastest paced of the all of the sciences. I can easily recall within my own lifetime that legitimate professional astronomers would not acknowledge a belief that other stars elsewhere in our galaxy may have had planets revolving around them! Now we know of some 5,000 such planets, even assigning them the nomenclature of “exoplanets,” —all of which at first were super-Jupiters. Now we know that the abundance of super-Jupiters was simply an artifact of their size being a part of the ease of their being detected, as now we know of numerous exoplanets of earth’s size and type.
Now we are looking for and finding the lost siblings of our own sun scattered around the galaxy, made possible with great ease from their spectrographic signatures, along with our capacity to collect, collate,and analyze data with almost instantaneous ease with modern computers. I think it’s fascinating that our sun may have had many thousands of siblings, all having been created at the same time from a supermassive galactic cloud of dust and gas that some force compressed into being a star nursery, maybe even when our galaxy encountered a small or a dwarf Galaxy, out beyond the Milky Way’s periphery and adding it to our galaxy’s body creating our own Sagittarius spiral arm.
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Well, technological progress helps improve astronomical studies, so we’re quickly learning a lot about what’s out there obtaining new answers but also getting new questions.