Category: Stellar Physics

How Big is the Biggest Star in the Universe?

A comparison between the Sun and a hypermassive star. Credit: NASA

So how big is it? According to Fraser at the Universe Today, the largest known star is VY Canis Majoris. This is a massive star, otherwise known as a red hypergiant star and this one sits in the constellation Canis Major, about 5000 light years from Earth. Apparently it is more than 2100 times the size of our Sun, a monster! This star is so big that light takes more than eight hours to cross its circumference. In fact, this star, if placed in the centre of the Solar System, it would reach as far as the orbit of Saturn.

Although VY Canis Majoris is big, it isn’t as big as the biggest star could be. If it was cooler, a similar star could reach over 2600 times the size of our Sun…

Could a Wolf-Rayet Star Generate a Gamma Ray Burst?

Gamma ray bursts (GRBs) are the most energetic events to be seen in the observable universe. On March 19th, a record breaking GRB was observed in the constellation of Boötes by NASA’s Swift Observatory and ground based telescope arrays (i.e. the Polish “Pie of the Sky” GRB detector). This was an explosion unparalleled with anything we have ever seen. Not only was it the brightest GRB, it was the most distant GRB – this explosion occurred 7.5 billion years ago (it was therefore located 7.5 billion light years away). Taking measurements of the spectrum of light from these events not only helps us understand what causes such a massive detonation, but also reveals the nature of the Universe when it was half the age it is now.

In a new publication headed by the University of Utrecht, in The Netherlands, the highly dynamic and self-destructive Wolf-Rayet star has been singled out as a possible GRB progenitor after some complex tidal interactions with a binary partner, spinning-up the star until it collapses and unleashes vast amounts of energy into space…
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How do you catch a Supernova in the Act? Build a Neutrino Detecting, Early Warning Device.

The massive star, Eta Carinae, explodes producing a huge pair of gas and dust clouds captured by the Hubble telescope. Image credit: NASA and Jon Morse, University of Colorado.

Observing a supernova as it happens is a very tough thing to do. If you blink, you’ll miss it. Astronomers are constantly trying to find ways to look in the direction of a massive star just before it blows, but supernova prediction is a very young science. Now, combining the sensitivity of neutrino detectors and attempting to make the data as “real time” as possible, the SuperNova Early Warning System (SNEWS) is born, sending you a neutrino weather forecast direct to your inbox hours before a star explodes.
Continue reading “How do you catch a Supernova in the Act? Build a Neutrino Detecting, Early Warning Device.”