Regardless of the scientific discipline involved, it seems that the idea of producing a twin, or a perfect replica, of a species, fascinates whether it involves some of our closest biological relatives or even digging into the past to return life to extinct animals like the long forgotten Siberian lion.
Even more exciting is when scientific studies leading to the discovery of previously unknown duplicates existing in nature. Now, it seems, a group of researchers has discovered evidence of the mother of all twins: the Sun.
An international team researchers of the Instituto de Astrofísica e Ciências do Espaço (IA) carried out the exciting work related to finding the stellar twin. Named HD 186302, the identical binary twin is located a staggering 184 light years away. Although the existence of solar siblings is relatively well known, finding the stellar twin proved a very time-consuming challenge for the researchers.
A Painstaking Process of Elimination
The operation was part of the team's AMBRE project, the name describing "the very large spectra database of solar vicinity stars". To narrow down the list of roughly 17,000 candidates which were identified as part of the group, the researchers used a combination of (1) Gaia DR2 astrometric data and (2) high-resolution spectroscopic parameters to make some age determination.
Next, the pool was dramatically sized down to 55 stars, based on their similar metallicities. Once the list of stars whittled down to a mere dozen, they knew they were truly on to something. Comparing the stellar ages cut the numbers down to only four, and once they discovered only a couple of these had carbon isotopic ratios compatible with the sun, HD 186302 rose to the top among the final four.
Vardan Adibekyan, of IA and the University of Porto, explains the unique challenges, and opportunities, that their work presented: “Since there isn’t much information about the Sun’s past, studying these stars can help us understand where in the Galaxy and under which conditions the Sun was formed.”
Expanding the Research
Most significantly, as astronomers are only intimately familiar with life in our Solar System, there is a possibility that solar twins can provide many clues, for everything from planetary formation to kinematics. After all, HD 186302 possesses the same luminosity, temperature, size, age and chemical composition of the sun.
Still, Adibekyan believes that we should reserve our excitement for now: “Some theoretical calculations show that there is non-negligible probability that life spread from Earth to other planets or exoplanetary systems, during the period of the late heavy bombardment.
If we are lucky, and our sibling candidate has a planet, and the planet is a rocky type, in the habitable zone, and finally if this planet was 'contaminated' by the life seeds from Earth, then we have what one could dream – an Earth 2.0, orbiting a Sun 2.0.”
Details about the study appear in a paper, titled "The AMBRE project: searching for the closest solar siblings," which was published November 16th in the Astronomy & Astrophysics journal.