Brought to you by Newscorp Australia

Neutron star amazes with ‘totally unexpected’ light display

Reuters, February 20, 2022 2:30PM Kids News

Print Article

This image shows a new view of the Milky Way from the Murchison Widefield Array, with the lowest frequencies in red, middle frequencies in green and the highest frequencies in blue. The star icon shows the position of the mysterious repeating transient. Picture: Dr Natasha Hurley-Walker/ICRAR/Curtin/GLEAM Team media_cameraThis image shows a new view of the Milky Way from the Murchison Widefield Array, with the lowest frequencies in red, middle frequencies in green and the highest frequencies in blue. The star icon shows the position of the mysterious repeating transient. Picture: Dr Natasha Hurley-Walker/ICRAR/Curtin/GLEAM Team

space

Reading level: orange

Scientists have spotted what seems to be an incredibly dense star behaving unlike anything ever seen – and they suspect it might be an exotic* astrophysical* object whose existence has only been a theory until now.

The object, first spotted in outback WA using the Murchison Widefield Array telescope, unleashed huge bursts of energy roughly three times per hour when viewed from Earth during two months in 2018, researchers said.

It may be the first known example of what is called an “ultra-long period magnetar*,” they said. This is a variety of a neutron star – the compact collapsed core of a massive star that exploded as a supernova*- that is highly magnetised and rotates relatively slowly, as opposed to fast-spinning neutron star objects called pulsars that appear from Earth to be blinking on and off within milliseconds or seconds.

media_cameraAn artist’s impression of what the object might look like if it’s a magnetar, an incredibly magnetic neutron star, some of which sometimes produce radio emission. Picture: ICRAR

“It’s mind-bogglingly wonderful that the universe is still full of surprises,” said radio astronomer Dr Natasha Hurley-Walker at the Curtin University post of the International Centre for Radio Astronomy Research (ICRAR), lead author of the study published this week in the journal Nature.

The object may be continuously beaming strong radio waves from its north and south poles. As that beam swept through the line of sight from Earth’s vantage* point, it appeared to switch on every 18 minutes and 11sec for about 30 to 60sec, then off again. That is an effect similar to a lighthouse, with a rotating light that seems to blink on and off from the perspective* of a stationary* observer.

It was found in a broader research effort mapping celestial* sources of radio waves.

“This is an entirely new kind of source that no one has ever seen before,” Dr Hurley-Walker said. “And while we know the Milky Way must be full of slowly spinning neutron stars, no one expected them to be able to produce bright radio emission like this. It’s a dream come true to find something so totally unexpected and amazing.”

media_cameraPart of the Murchison Widefield Array telescope in outback WA, where the star was spotted during mapping of celestial sources of radio waves. Picture: Pete Wheeler/ICRAR

It is located relatively close to Earth in cosmic terms, roughly 4200 light years away – the distance light travels in a year, or 59.5 trillion km.

“It’s incredibly bright when it’s on – It’s one of the brightest radio sources in the sky,” said study co-author Tyrone O’Doherty, a Curtin ICRAR doctoral student who found the object.

It fits into a category called “transients” – astrophysical objects that appear to turn on for limited amounts of time. “Slow transients” like a supernova can suddenly appear then disappear a few months later as the stellar explosion dissipates*. Pulsars are “fast transients,” rapidly blinking on and off. Transients between these two extremes had remained elusive* until now.

media_cameraThe location of the source in the sky in January 2022, marked with a large white star marker. At this time of year, it is above the horizon during the day. Image source: Stellarium

Neutron stars including pulsars are among the universe’s densest objects. They are roughly 12 km in diameter – akin* to the size of a city – but with more mass than our sun. A neutron star with an extreme magnetic field, a magnetar, could potentially power the radio pulsations, the researchers said.

As for why its rotation is so slow, it could be that it is very old and has slowed over time, according to Curtin ICRAR astrophysicist and study co-author Dr Gemma Anderson.

“This is more likely to be the first of its kind rather than one of a kind,” Dr Anderson said.

It might also be another type of dead star called a white dwarf or something completely unknown, according to Dr Hurley-Walker.

The researchers have not detected it again since 2018.

“We are now monitoring this object using many different radio telescopes in the hope it switches on again,” Dr Anderson said.

media_cameraThis image shows the magnificent Milky Way as viewed from Earth. The star icon shows the position of the mysterious repeating transient. Picture: Dr Natasha Hurley-Walker/ICRAR/Curtin

GLOSSARY

  • exotic: different, exciting, foreign, unknown
  • astrophysical: relating to branch of physics dealing with astronomical phenomena
  • magnetar: neutron star with a much stronger magnetic field than other neutron stars
  • supernova: star that dramatically increases in brightness after a huge explosion
  • vantage: position, view, standpoint
  • perspective: outlook, way of viewing something
  • stationary: not moving, motionless, standing still
  • celestial: in the sky or outer space as observed in astronomy
  • dissipates: disappear, vanish, evaporate, dissolve
  • elusive: difficult to find, slippery, hard to catch
  • akin: similar, related, close to, comparable

EXTRA READING

World’s most powerful space telescope launched

Mystery object spied on the moon

Black hole swallows neutron star

QUICK QUIZ

  1. Where was the object first spotted and using what type of telescope?
  2. The blinking light effect is similar to that created by what type of man-made structure on Earth?
  3. What are transients?
  4. What is the rough diameter of neutron a neutron star?
  5. What year was the neutron star last detected?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Identify key details
This news story goes into a lot of detail to explain different facts and theories about the object. Read the article carefully, highlighting the most important pieces of information only. Then make a dot-point list of key details that scientists believe to be true about the object.

Time: allow 20 minutes to complete this activity
Curriculum Links: English; Science

2. Extension
What has this news article left you wondering?

Write three questions that you hope scientists will find the answer to, in relation to the object in this story.

Time: allow 10 minutes to complete this activity
Curriculum Links: English; Science

VCOP ACTIVITY
Grammar and VCOP
The glossary of terms helps you to understand and learn the ambitious vocabulary being used in the article. Can you use the words outlined in the glossary to create new sentences? Challenge yourself to include other VCOP (vocabulary, connectives, openers and punctuation) elements in your sentence/s. Have another look through the article, can you find any other Wow Words not outlined in the glossary?

Extra Reading in space