Star mysteriously flickered for seven whole years before shining again: A cosmic mystery

(ORDO NEWS) — The huge star blinked for seven years, and at first no one noticed it.

But then the European Space Agency’s Gaia spacecraft saw a star known as Gaia17bpp suddenly flare brightly – and years later, researchers think they’ve finally figured out the cause.

The strange dimming of Gaia17bpp may indicate a small companion surrounded by a huge dusty disk.

The leading hypothesis is that Gaia17bpp, a red giant 55 times the size of the Sun, may be an example of an extremely rare binary star system whose light is blocked by a small companion star surrounded by a huge disk of dusty material that passes in front of a large star every 100 or 1000 years.

The goal of the Gaia spacecraft, launched in 2013, is to observe billions of stars, map their positions and obtain extremely detailed information about their characteristics, including their brightness.

“While exploring the Gaia data set, we came across a very unusual star,” said Anastasios “Andy” Tzanidakis, an astrophysicist at the University of Washington.

Archival data showed that around 2017, Gaia17bpp, which was barely detectable, began to brighten for about two and a half years, Tzanidakis said. The scientist noted that usually the stars do not behave this way.

Mysterious twinkling star

Tsanidakis and his colleagues turned to other archives to find out how the star has behaved in the past. They found Gaia17bpp records dating back to the 1950s. For most of this time, the red giant remained at a constant brightness.

“Then, around 2012, the star suddenly started to fade,” until it completely reappeared in 2019, Andy noted.

He added that the fact that such blinking has not been seen in the archives for more than 70 years suggests that such events occur on time scales of 100 or even 1,000 years.

“These eclipses are probably once in a lifetime and we won’t see them again,” Tsanidakis said.

Although the researchers are still not sure what causes the dimming, they believe that a tiny companion star may be orbiting Gaia17bpp.

This companion may be surrounded by an elongated disk of dust that exceeds the average Earth-Sun distance, the researchers say.

Tsanidakis linked the event to another mysterious star known as Epsilon Aurigae, a giant that undergoes a biennial eclipse every 27 years that could also be surrounded by a disk-bearing companion.

Several other stars are known to experience similar eclipses, but “it is still unclear what the connection is between all these systems,” the scientist said.

Flickering luminaries

The behavior of Gaia17bpp does not seem to be related to what is causing the strange twinkling of the star KIC 8462852, also called Tabby’s star or Boyajian’s star, Tsanidakis told reporters at a conference.

(Among other possible explanations for this star’s mysterious twinkling, some scientists have suggested that the star may be surrounded by an alien megastructure.)

Gaia17bpp’s behavior is also unlike the famous 2019 dimming of the giant star Betelgeuse, he added.

Tzanidakis and his colleagues are left with many questions about the Gaia17bpp flicker, such as whether it was the disc that actually caused the event, and if so, how the disc came about and what it’s made of.

Since this behavior is very rare, it may take some time to unravel these mysteries. But for now, it’s “the longest, deepest flicker we’ve found in public data archives,” Tzanidakis said.

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