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Saturday, September 23, 2023

Is THIS how the ‘superheroes of the star world’ form? Scientists spot a ‘magnetic monster’ that is about to explode into a supernova and become a mysterious dead magnetar


Astronomers have discovered a new type of star – a ‘magnetic monster’ that will one day explode to become a rare ‘magnetar’. 

Called HD 45166, the star is rich in helium and located about 3,000 light-years away from Earth in the constellation Monoceros.  

But what makes it really special is it’s the only massive helium star astronomers have ever observed that has a magnetic field – and a powerful one at that. 

HD 45166 has such a strong magnetic field – 100,000 times stronger than Earth’s – that astronomers think it will become a magnetar when it explodes into a supernova in around 1 million years. 

Magnetars are compact and highly magnetic stellar remnants with some of the most intense magnetic fields in the universe that violently eject bursts of energy

This artist impression shows HD 45166, a massive star recently discovered to have a powerful magnetic field of 43,000 gauss, the strongest magnetic field ever found in a massive star. Intense winds of particles blowing away from the star are trapped by this magnetic field, enshrouding the star in a gaseous shell as illustrated here. Astronomers believe that this star will end its life as a magnetar, a compact and highly magnetic stellar corpse

What are magnetars? 

Magnetars are neutron stars with an ultra-strong magnetic field – around a thousand trillion times stronger than Earth’s.

They are the most magnetic objects in the universe, but astronomers do not know how they form.  

Only about a dozen magnetars have been discovered so far.

How common are magnetars, and how did they gain their super magnetic strength are the key questions facing astronomers today. 

Source: NASA/Swinburne University of Technology

Not much has been known about the origin of magnetars until now, but experts think HD 45166 finally sheds light on their origin. 

A new study detailing the findings, conducted by an international team of astronomers, has been published today in the journal Science.

‘For the first time, a strong magnetic field was discovered in a massive helium star,’ said author André-Nicolas Chené at NOIRLab, an astronomical research centre based in Tucson, Arizona. 

‘Our study suggests that this helium star will end its life as a magnetar.’

NASA describes magnetars as the ‘superheroes of the star world’ because they’re endowed with a colossal magnetic field strength that has baffled scientists for years. 

Magnetars are a type of neutron star – the collapsed cores of some massive stars that pack roughly the mass of our sun into a region the size of a city. 

In a typical neutron star, the magnetic field is trillions of times that of Earth’s magnetic field, but in a magnetar the magnetic field is another 1,000 times stronger.

Therefore, magnetars are a very special type of neutron star. 

However, astronomers don’t know exactly how magnetars form, how common they are or even how they produce such colossal magnetic fields. 

What’s more, magnetars are extremely small – just 10 to 12 miles (15 to 20 km) across – and so are too distant for even the best telescopes to see any details on their surfaces.

The team therefore made observations using an instrument on the Canada-France-Hawaii Telescope that can detect and measure magnetic fields. 

In particular, they turned their attention towards HD 45166, a star that’s been known about for over a century by astronomers.

The first observations of the star were made in 1922 and astronomer Carol Jane Anger noted in a 1933 publication that was ‘a first of its kind’. 

This artist's impression shows a highly unusual helium star that is destined to become one of the most magnetic objects in the universe - a magnetar. The star is unusual because of its strong magnetic field. In a few million years, HD 45166 will explode as a very bright, but not particularly energetic, supernova. During this explosion, its core will contract, trapping and concentrating the star’s already daunting magnetic field lines. The result will be a neutron star with a magnetic field far greater than its progenitor

This artist’s impression shows a highly unusual helium star that is destined to become one of the most magnetic objects in the universe – a magnetar. The star is unusual because of its strong magnetic field. In a few million years, HD 45166 will explode as a very bright, but not particularly energetic, supernova. During this explosion, its core will contract, trapping and concentrating the star’s already daunting magnetic field lines. The result will be a neutron star with a magnetic field far greater than its progenitor

Pictured, the Canada-France-Hawaii and Gemini Telescopes Located at the Mauna Kea Observatories on the Big Island of Hawaii

Pictured, the Canada-France-Hawaii and Gemini Telescopes Located at the Mauna Kea Observatories on the Big Island of Hawaii

What is a supernova? 

A supernova is the explosion of a star.

It is the largest explosion that takes place in space. 

They can occur at the end of a single star’s lifetime. 

As the star runs out of nuclear fuel, some of its mass flows into its core.

The core gets so heavy that it cannot withstand its own gravitational force.

The core collapses, which results in the giant explosion of a supernova. 

Source: NASA 

Lead author of the new study Tomer Shenar at the University of Amsterdam said he and colleagues suspected the star was ‘weird’, but didn’t think it could be a precursor of a magnetar. 

‘We didn’t know it would be the magnetic monster that it is at first,’ Professor Shenar told MailOnline.

‘Only at a later stage, the hypothesis that it might be magnetic arose and was later proven with the new data presented in our study.’ 

Observations revealed HD 45166 has an incredibly strong magnetic field of 43,000 gauss – a unit of measurement of magnetic induction, also known as Gs.  

This makes it the only massive helium star ever observed with a magnetic field, as well as the strongest magnetic field ever detected in a massive star.

Also, 43,000 gauss is almost 100,000 times stronger than Earth’s magnetic field (which enables compasses to operate and birds to navigate). 

Intense winds of particles blowing away from HD 45166 are trapped by its magnetic field, enshrouding the star in a gaseous shell. 

The team strongly believe that HD 45166 will turn into a magnetar in around one million years’ time – relatively short in an astronomical time scale considering the Earth is 4.5 billion years old. 

Pictured, the evolution of a massive magnetic helium star into a magnetar. Panel one illustrates HD 45166 as it appears today. Panel two illustrates how HD 45166 will explode as a very bright, but not particularly energetic, supernova. During this explosion, its core will contract, trapping and concentrating the star’s already daunting magnetic field lines. Panel three illustrates the ultimate fate of HD 45166 after its core has collapsed, resulting in a neutron star with a magnetic field of around 100 trillion gauss (a magnetar) - the most powerful type of magnet in the universe

Pictured, the evolution of a massive magnetic helium star into a magnetar. Panel one illustrates HD 45166 as it appears today. Panel two illustrates how HD 45166 will explode as a very bright, but not particularly energetic, supernova. During this explosion, its core will contract, trapping and concentrating the star’s already daunting magnetic field lines. Panel three illustrates the ultimate fate of HD 45166 after its core has collapsed, resulting in a neutron star with a magnetic field of around 100 trillion gauss (a magnetar) – the most powerful type of magnet in the universe

For a star to become a magnetar, it needs to fulfill two conditions which the researchers think HD 45166 meets. 

Firstly, it needs to become a neutron star when it dies.

‘This is not a certainty, but it seems to be just about massive enough to undergo core-collapse into a neutron star and this is supported by our models,’ Professor Shenar told MailOnline. 

Secondly, it needs to have a sufficiently strong magnetic field – and the team definitely know that HD 45166 does. 

‘So, if it collapses to a neutron star, the field of the newly-born neutron star is bound to reach hundreds of trillions of gauss – the typical field of a magnetar, Professor Shenar told MailOnline.

According to the academic, HD 45166 has no known planets orbiting it and is ‘unlikely’ to have any yet to be undiscovered.

‘The star is about 100 million years old – that’s more or less the time it takes for planets to form – but we cannot rule it out,’ he told MailOnline. 

SUPERNOVAE OCCUR WHEN A GIANT STAR EXPLODES

A supernova occurs when a star explodes, shooting debris and particles into space.

A supernova burns for only a short period of time, but it can tell scientists a lot about how the universe began.

One kind of supernova has shown scientists that we live in an expanding universe, one that is growing at an ever increasing rate.

Scientists have also determined that supernovas play a key role in distributing elements throughout the universe.

In 1987, astronomers spotted a ‘titanic supernova’ in a nearby galaxy blazing with the power of over 100 million suns (pictured)

In 1987, astronomers spotted a ‘titanic supernova’ in a nearby galaxy blazing with the power of over 100 million suns (pictured)

There are two known types of supernova.

The first type occurs in binary star systems when one of the two stars, a carbon-oxygen white dwarf, steals matter from its companion star.

Eventually, the white dwarf accumulates too much matter, causing the star to explode, resulting in a supernova.

The second type of supernova occurs at the end of a single star’s lifetime.

As the star runs out of nuclear fuel, some of its mass flows into its core.

Eventually, the core is so heavy it can’t stand its own gravitational force and the core collapses, resulting in another giant explosion. 

Many elements found on Earth are made in the core of stars and these elements travel on to form new stars, planets and everything else in the universe.



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