From MIT Caltech Advanced aLIGO via Science Alert: “Astronomers Detect a Burst of Gravitational Waves From The Direction of Betelgeuse”

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Science Alert

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Betelgeuse captured in 2010. (Rogelio Bernal Andreo/Wikimedia Commons/CC BY-SA 3.0)

20 JAN 2020
EVAN GOUGH

Gravitational waves [below] are caused by calamitous events in the Universe. Neutron stars that finally merge after circling each other for a long time can create them, and so can two black holes that collide with each other. But sometimes there’s a burst of gravitational waves that doesn’t have a clear cause.

One such burst was detected by LIGO/VIRGO on January 14, and it came from the same region of sky that hosts the star Betelgeuse. Yeah, Betelgeuse, aka Alpha Orionis. The star that has been exhibiting some dimming behaviour recently, and is expected to go supernova at some point in the future.

Might the two be connected?

Betelgeuse is a red supergiant star in the constellation Orion. It left the main sequence about one million years ago and has been a red supergiant for about 40,000 years. Eventually, Betelgeuse will have burned enough of its hydrogen that its core will collapse, and it will explode as a supernova.

Recently, Betelgeuse dimmed. That set off all kinds of speculation that it might be getting ready to go supernova. Astrophysicists quickly poured water on that idea. There’s no exact number, but it’s estimated that Betelgeuse won’t go supernova for another 100,000 years. But when a star dims, there’s clearly something going on.

Is this new burst of gravitational waves connected to Betelgeuse’s recent dimming? To its future supernova explosion?

Astronomers understand that Betelgeuse is a variable star, and its brightness can fluctuate. Stars like Betelgeuse aren’t just static entities. It’s a semi-regular variable star that shows both periodic and non-periodic changes in its brightness.

The kind of gravitational waves that LIGO detected are called burst waves. It’s possible that a supernova could produce them, but Betelgeuse hasn’t gone supernova and won’t for a long time.

Some think that the detection of gravitational waves in Betelgeuse’s direction is unrelated to the star itself. In fact, the detection of the burst waves may not have even been real.

Christopher Berry is an astrophysicist studying gravitational waves at Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics.

On Twitter he spoke up about the gravitational burst waves.

Andy Howell from Las Cumbres Observatory studies supernova and dark energy. He had something to say on Twitter too, and appeared to be having fun with the whole thing. He even walked outside to check up on Betelgeuse after the detection of the burst gravitational waves.

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So there you have it. No supernova for now, anyway. The burst gravitational waves may just be a glitch, and Betelgeuse’s dimming is well-understood and not a threat.

One day Betelgeuse will explode, and our night sky will change forever. But for us here on Earth, that supernova poses no problem.

An exploding star is an awesome event. And it produces a cataclysm of deadly radiation. X-rays, ultraviolet radiation, and even stellar material are ejected with great force. The deadliest radiation is gamma rays, and Betelgeuse likely won’t even produce any of those when it blows.

But in any case, we’re about 700 light years away from Betelgeuse, and that’s way too much distance for us to worry.

The biggest fallout is that the Orion constellation will change forever. And there’ll be a new object to study in the sky: a supernova remnant.

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The Collaborations

LIGO is funded by NSF and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council-OzGrav) making significant commitments and contributions to the project. More than 1,200 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. A list of additional partners is available at https://my.ligo.org/census.php.

The Virgo collaboration consists of more than 300 physicists and engineers belonging to 28 different European research groups: six from Centre National de la Recherche Scientifique (CNRS) in France; 11 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; two in the Netherlands with Nikhef; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; Spain with IFAE and the Universities of Valencia and Barcelona; two in Belgium with the Universities of Liege and Louvain; Jena University in Germany; and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy, funded by CNRS, INFN, and Nikhef. A list of the Virgo Collaboration can be found at http://public.virgo-gw.eu/the-virgo-collaboration/. More information is available on the Virgo website at http://www.virgo-gw.eu.


VIRGO Gravitational Wave interferometer, near Pisa, Italy


Caltech/MIT Advanced aLigo Hanford, WA, USA installation


Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger

ESA/eLISA the future of gravitational wave research

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Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)