Astronomers Unmask a Supernova Impostor

Astronomers have identified that the star AT 2016blu is not an imminent supernova but rather a luminous blue variable star with a previously unseen companion. The star, located about 29 million light years away, is 33 times more massive than the Sun and has erupted 27 times since its discovery in 2012. New research suggests that the outbursts are caused by a binary system in which the primary star is a luminous blue variable, and the companion is a compact object, such as a black hole or neutron star. The study, titled "AT 2016blu: Accretion-Powered Outbursts in a Luminous Blue Variable and Compact Object Binary," presents new x-ray observations that show the star's outbursts are due to accretion of material from its companion. The research indicates that the system is a high-mass X-ray binary, and the outbursts are intermittent, with the mass transfer occurring during periastron passages. The study also highlights that the star is the first known case of an LBV SN impostor whose outbursts are driven by accretion onto a compact companion. The discovery will help improve understanding of how massive stars and their companions evolve and interact.

• AT 2016blu is a luminous blue variable star with a previously unseen companion.
• The star is about 29 million light years away and is 33 times more massive than the Sun.
• The outbursts are caused by accretion of material from a compact companion, not by a supernova.
• The study shows that the system is a high-mass X-ray binary, with the primary star being a luminous blue variable.
• The research indicates that the outbursts are intermittent, with mass transfer occurring during periastron passages.
• The discovery of AT 2016blu as an LBV SN impostor will help improve understanding of how massive stars and their companions evolve and interact.

The research emphasizes that studying such systems will advance understanding of the role of massive stars in the universe, as they forge heavy elements and spread them into space. While astronomers know a lot about luminous blue variables, there are still many open questions about their evolution and how they die. The study also highlights that the discovery of AT 2016blu as an LBV SN impostor connects it to a growing class of models explaining pre-SN transient phenomena. The Vera Rubin Observatory's 10-year sky survey will uncover more of these types of targets.

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