New clues confirm that Tabby’s star is dimmed by dust

KIC 8462852 at infrareds and ultraviolets (Image:  IPAC/NASA for infrareds, STScI (NASA) for ultraviolets)
KIC 8462852 at infrareds and ultraviolets (Image: IPAC/NASA for infrareds, STScI (NASA) for ultraviolets)

An article published in “The Astrophysical Journal Letters” describes the results of new observations of the star KIC 8462852, commonly known as Tabby’s star or sometimes Boyajian’s star. A team of astronomers led by Tabetha S. Boyajian, the astronomer who in 2015 realized that its brightness was changing rapidly, dimming up to 20% within a few days, conducted a research possible thanks to a funding obtained through a campaign on Kickstarter. The conclusions confirm the theory of dust that obscures the star, in particular at certain frequencies.

The story of Tabby’s star’s study mixes classical astronomy based on observations with telescopes with Internet uses such as crowdfunding and what’s called citizen science, as Planet Hunters website’s visitors contributed significantly to the discovery of its brightness changes. Even the most folkloristic part of the Internet was involved because an alien mega-structure is a very common hypothesis in groups that prefer not to spoil a good story with the truth.

The crowdfunding campaign on the Internet allowed to raise over $100,000 to allow to obtain a series of new observations of Tabby’s star with ground-based telescopes. Continued observations were needed to collect more data on its sudden dimmings. Tabetha S. Boyajian directed a large group of astronomers in collaboration with the Las Cumbres Observatory, a global network of robotic telescopes that are coordinated precisely to carry out continuous observations over long periods.

The observations of Tabby’s star went ahead between March 2016 and December 2017. Between May and September 2017 there were dimmings in four separate episodes, each of which received a name thanks to the vote from the fundraising supporters: Elsie, Celeste, Scara Brae and Angkor. The last two names are those of two lost cities, respectively in Scotland and Cambodia, to remember that what we’re seeing happened in the past since the star is almost 1,500 light years from Earth.

An article published in October 2017 in the journal “The Astrophysical Journal” claimed that changes in Tabby’s star’s brightness were caused by a dense cloud of dust orbiting it. The conclusions of Tabetha S. Boyajian’s team are similar after the discovery that some electromagnetic frequencies are obscured far more than others.

According to the original hypothesis of Tabetha S. Boyajian’s team there are exocomets, meaning comets that are part of that star system, which irregularly obscure Tabby’s star. The new clues that confirm the presence of dust masses don’t rule out other possibilities for its origin but rule out the hypothesis of the alien megastructure. It remains an interesting object of study that involved a lot of ordinary people in a scientific research that’s not over yet.

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