HEN News 02/2024 (The one with Scary Barbie in it)

American Association of Variable Star Observers (AAVSO)
Sun, 01/28/2024 - 20:41

Soon after the Zwicky Transient Facility (ZTF) had recorded the optical transient ZTF20abrbeie, it became clear that this one didn't quite match any of the more frequent types of an extra-galactic transient like a supernova, Gamma Ray Burst afterglow or a common type of AGN outburst. The light curve and spectroscopy hinted that this one was very energetic, and probably of some rarer type. The event also is known as AT 2021lwx, a name that is not as conveniently turned into an easy-to-remember nickname like "The Cow " (AT 2018cow), but we have seen with "The Kwala" (ZTF18abvkwla) that you cal also twist and shake the longer ZTF designations into words, so ZTF20abrbeie enventually became "Barbie" and lately "Scary Barbie" because it is frighteningly energetic. It is now believed that what happens here is a Black Hole shredding a passing star into pieces and then slowly feeding on the remains...scary stuff indeed.

This event still inspires new scientific papers, e.g. see these relatively recent preprints

"AT2021lwx: Another Neutrino-Coincident Tidal Disruption Event with a Strong Dust Echo?" https://arxiv.org/abs/2401.09320

"Scary Barbie: An Extremely Energetic, Long-Duration Tidal Disruption Event Candidate Without a Detected Host Galaxy at z = 0.995"  https://arxiv.org/abs/2302.10932

The second paper is describing the discovery of the event in some detail, and this is what is most interesting for us amateur astronomers perhaps. As you can see from the event name (the naming scheme is the same as for super novae: a, b,...aa...etc) ZTF generates a crazy high number of transients each day, most of them not-so-interesting because they are just new instances of well-understood phenomena. Nothing to see here, please move on! It requires clever computer programs and artificail intelligence to pick out s subset for deeper investigations, and the pipeline that singled out "Scary Barbie" was REFITT (Recommender Engine for Intelligent Transient Tracking). Interestingly, we as amateur  astronomers can subscribe to REFITT and receive a steady stream of observation recommendations for  potentially interesting transients, and REFITT is smart enough to pick targets depending on your equipment capabilities and the location of your observation site. Check it out:  https://refitt.physics.purdue.edu/#get-involved

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