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It’s been suspected for a long time that our sun has a lost twin, let’s find out more about it.

Our sun, it turns out, when it came into being, some 4.6 billion years back, was not alone. It was more like a middle child in a family of thousands of siblings! Though most of its kinfolks have now spread far and wide by now, one supposedly long-lost sibling had been spotted. Not only that, the one that had been found can very well be the sun’s ‘twin’. And that’s very exciting news indeed, as it might lead astronomers to extraterrestrial life forms.

This is not a fortuitous find as the search read on for decades. Since the 80s, a hypothesis started to circulate that our star has an ‘evil twin’ which was named ‘Nemesis’. It was so named because every time it would pass by our solar system every 36 million years or so, it’d inevitably portend a wave of comets crashing onto it, which some theorists believe that led to the mass extinction events.

Sifting Through AMBRE

Though the said Nemesis is still absconding, it did prompt researchers to sift through a huge database of the spectra of thousands of closeby stars. Know as AMBRE; this data comprises the chemical composition and age of those stars which can be cross-referenced with findings from Gaia survey.

Shortlisting Suns

Out of the 17,000 catalogued stars, 55 seemed to be potential family-members, owing to its metal contents resembling that of our sun. A further sieve by the chemical abundances of certain elements whittled the list to a dozen. Determining their age narrowed the possibilities to four, and finally, measurement of the carbon isotopic ratios helped scientists to zero in on one.

Solar Twinning

The one that glowed checked out with our sun’s stats in terms of mass, age, metallic content, chemical abundance and carbon isotope ratios. Provisionally known as HD 186302, it was found out to be more than a sibling. It’s was an almost identical twin. Residing about 184 light-years from Earth, it is a G3 type main-sequence star. 

Incidentally, though HD 162826 was the first-ever Sun sibling that was found, HD 186302, is the closest match.

Another Sun; Another Earth?

Till now that’s no evidence that HD 186302 harbours any planets. However, theoretic calculations exhibit that there’s a slim probability that life could have spread from Earth to other planets or exoplanetary systems, during the heavy disruptions period. If this Sun has a rocky type planet in the habitable zone and if the building blocks of life could have made it there, then we might be looking at a twin Earth of a twin Sun.

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