BENGALURU: An Indian scientist from the Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital — Alok C Gupta — is part of a team of 22 scientists from an international group which has proposed that those parts of space where multiple stars seem to disappear could be the best places to look for extraterrestrial intelligence (ETI).

The Vanishing and Appearing Sources during a Century of Observations (VASCO) team has chanced upon a hundred missing stars-like objects by comparing old and new observations of about 600 million heavenly objects recorded in US Naval Observatory (USNO).

While searching for extraterrestrial life and intelligence has been a fascinating subject for more than two decades, the VASCO team does not claim that it has already found signs of aliens during its studies. It, however, argues in its latest study published in Astronomical Journal, that unless a star directly collapses into a blackhole, there is no known physical process by which it could physically vanish.

In the context of Search for ETI (SETI), the leader of the project, Beatriz Villarroel of Stockholm University, along with others has “proposed to search surveys for vanished stars in our Galaxy as probes of “impossible effects” that could only be ascribed to an extraterrestrial technology, due to the high likelihood of this as an observational signature.”

Elaborating on why vanishing stars are good places to look for ETI, Gupta told TOI: “These are the most probable places to look for. These stars have not gotten trapped in blackholes as there are no signs of blackholes in the vicinity, which is why we have proposed that there could be ET activity. We are not making any strong claims yet, but this is the first time that such a project is happening, and we will find more.”

The study, while reiterating that it has found no concrete evidence yet to suggest presence of ET, said VASCO will generate large lists of candidate objects in searches for vanishing stars in the next phase.

“Individually, these serve no purpose unless verified...However, if a region of the sky has a tendency to produce an unexpectedly large fraction of candidates relative to the background, this region or “hot spot” may deserve some extra attention,” the study reads.

As a part of VASCO’s research programme, the team plans to combine all the unverified initial results from many different search programmes and aims to visualize the background of the unverified candidates in a two-dimensional projection of the sky.

“Altogether, this noisy background of neglected candidates could reveal “hot spots” of transient activity, where for some reason many candidates are concentrated. Doing this iteratively with reliable clustering methods and zooming in on the most active regions in our SETI (or technosignature) searches, we can identify the most probable locations to host extraterrestrial intelligence,” the study added.

The implications of finding such objects extend from traditional astrophysics fields to the more exotic searches for evidence of technologically advanced civilisations.

Aside from Gupta, VASCO, an international project led by Dr Beatriz Villarroel of Stockholm University and Spain's Instituto de Astrofísica de Canarias consists of scientists from Sweden, Spain, Finland, the US, Netherlands, Belgium, Switzerland , Cremia, Ukraine, and the UK.

The team of scientists has compared old and new observations of about 600 million heavenly objects recorded in USNO catalogue containing 1 billion astronomical objects with Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) catalogue having about 2-3 billion objects.

This is presently the largest digital sky survey located at Haleakala Observatory , Hawaii, USA, consisting of astronomical cameras, telescopes and a computing facility that surveys the sky for moving or variable objects.

For data analysis purpose, the team used very modern and sophisticated 3-TB (terabyte) cloud environment provided by the Uppsala Multidisciplinary Center for Advanced Computational Science (UPPMAX), which is part of the Swedish National Infrastructure for Computing (SNIC).

