Scientists release Exotica catalogue – a list of all known celestial objects in the Universe

Breakthrough Listen, a programme that seeks to find signs of intelligent life in the Universe, released a catalogue – Exotica – a diverse list of celestial objects which can interest astronomers searching for technosignatures (indicators of technology developed by extraterrestrial intelligence).

The team, searching for signs of extraterrestrial intelligence, published a catalogue which comprises a collection of over 700 distinct targets, ranging from comets to galaxies, from mundane objects to the rarest, and even violent celestial phenomena.

The new Exotica catalogue is the centrepiece of Breakthrough Listen’s efforts to expand the diversity of targets. "The crucial principle behind it is the concept of survey breadth – the diversity of objects observed during a program," it said in a release. According to the research paper, this is the first-ever list published with the purpose of "spanning the breadth of astrophysics."

"This catalogue should help astronomers constrain the range of potential habitats for extraterrestrial intelligence, as well as rule out the possibility that any phenomena widely considered natural are in fact artificial. Conversely, it may identify natural events, or confounding data such as interference, that mimic the kinds of artificial signal SETI researchers are on the lookout for," it added.

The catalogue is accompanied by an extensive discussion of the classification of objects, as well as plans for upcoming and potential observations based on this work.

“The publication of this catalogue is a new and significant step for the program,” said Yuri Milner, the founder of the Breakthrough Initiatives.

Exotica catalogue contains four categories of objects – prototypes, superlatives, anomalies and controls. While prototypes is a list containing at least one example of every known kind of celestial object; superlatives serve as a record of objects with the most extreme properties like the hottest planet, stars with unusually high or low metal content, the densest galaxy among others. Anomalies deal with targets whose behaviour is currently not satisfactorily explained; whereas controls sample sources which are not expected to produce positive results.

“Until we understand more about the forms of another civilisation and its technology, we should investigate all plausible targets. Cataloguing them is the first step toward that goal," said S Pete Worden, Executive Director of the Breakthrough Initiatives.

Dr Brian Lacki, the author of the paper, said, “Sometimes a major new discovery was missed when nobody was looking in the right place because they believed nothing could be found there. Are we looking in the wrong places for technosignatures? The Exotica catalogue will help us answer that question.”