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Podcaster: Richard Drumm

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Title: Space Scoop: Poof! A Massive Disappearance!

Organization: 365 Days Of Astronomy

Link : http://365daysofastronomy.org/ ; https://www.unawe.org/kids/unawe2024/

Description: Space scoop, news for children. 

This mischievous star is located 75 million light-years away in the Kinman Dwarf Galaxy, a BCD, or blue compact dwarf galaxy also called PHL 293B, in the constellation Aquarius. Between 2001 and 2011, various teams of astronomers have studied this mysterious massive star, and now it was 2019 and it was time to have another look. To their great surprise, though, the star had disappeared! It was by far the brightest thing in this little galaxy, and it was just plain gone.

Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.

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Transcript:

This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.

Today’s story is…

Poof! A Massive Disappearance!

Like a magician’s astonishing final magic trick, a giant star has recently disappeared from plain sight!

This is one peculiar magician!

This mischievous star is located 75 million light-years away in the Kinman Dwarf Galaxy, a BCD, or blue compact dwarf galaxy also called PHL 293B, in the constellation Aquarius.

Between 2001 and 2011, various teams of astronomers have studied this mysterious massive star. Their research suggested that it was in a late stage of its life. 

It was an LBV, a Luminous Blue Variable. So it was hugely luminous, 2 to 3 million times as bright as our Sun, and with a crazy fast 1,000 km per second stellar wind. It was clear that it was in, as the astronomers called it: an eruptive state.

Recently, a team of European Southern Observatory astronomers decided to take a new look at the star with the ESO’s VLT, the Very Large Telescope at the Paranal Observatory in Chile, to study how massive stars like this one end their lives. 

This star is exactly what they wanted. They’d studied it last in 2011 and now it was 2019 and it was time to have another look. 

To their great surprise, though, the star had disappeared! It was by far the brightest thing in this little galaxy, and it was just plain gone.

Now you see it, now you don’t!

Like curious audience members at a magic show, we are left to ponder how this giant star vanished. 

If the star had died in a giant supernova explosion, as is common for this type of star, it’s believed that astronomers around the world would have noticed this bright event. Would’ve been hard to miss!

Instead, astronomers suggest this star may still be out there, but it’s just that we can no longer detect it. The star may have experienced a transformation into a star that is simply less luminous. 

This would mean it’s not releasing as much energy for the ESO astronomers to detect with their spectroscopes. You see, spectroscopes need lots of photons to give us a nice spectral graph to study.

One possibility is it could have had a simple drop in brightness with a shift to a higher temperature, combined with it simultaneously putting out a massive dust cloud, obscuring the star.

Another possibility is that it collapsed into a black hole, without creating a supernova explosion!

This would be quite an astonishing discovery, as our current understanding of how massive stars die is that they always produce a supernova before collapsing into a black hole or a neutron star. 

Either way, there’s a big, bright flash of light announcing the explosion! 

A third possibility is that the star did produce a supernova but it was missed by astronomers as it would have happened in the late 1990s when no data was available. 

With this scenario the LBV observations in the 2001 to 2011 era would have been the result of ejecta from the supernova hitting a dense circumstellar disk.

The astronomers can’t rule this possibility out as of now.

Future studies hope to better understand the process that explains how this mysterious star seems to have disappeared from our sight. 

Meanwhile we must be patient. [Sigh]

Hey Here’s A Cool Fact:

The ESO’s ELT, the Extremely Large Telescope, due to start observations in 2025, will be the next logical step in studying this weird star. That instrument will be able to resolve the individual stars in this galaxy even better than the Hubble did!

Then we’ll know which of the 3 possible scenarios is correct.

Maybe there’ll be a 4th possibility!

Thank you for listening to the 365 Days of Astronomy Podcast!

End of podcast:

365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by Planetary Science Institute. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. 

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