Nasa scientists get unprecedented view as black hole rips apart a star

Scientists still don't fully understand the strange and powerful blasts that come out of such an event

Andrew Griffin
Thursday 26 September 2019 11:23 EDT
Comments
NASA scientists get unprecedented view as black hole rips apart a star

Your support helps us to tell the story

From reproductive rights to climate change to Big Tech, The Independent is on the ground when the story is developing. Whether it's investigating the financials of Elon Musk's pro-Trump PAC or producing our latest documentary, 'The A Word', which shines a light on the American women fighting for reproductive rights, we know how important it is to parse out the facts from the messaging.

At such a critical moment in US history, we need reporters on the ground. Your donation allows us to keep sending journalists to speak to both sides of the story.

The Independent is trusted by Americans across the entire political spectrum. And unlike many other quality news outlets, we choose not to lock Americans out of our reporting and analysis with paywalls. We believe quality journalism should be available to everyone, paid for by those who can afford it.

Your support makes all the difference.

Nasa has managed to get an unprecedented view of a black hole ripping apart a star.

The new observations – which allowed scientists to see the cataclysmic phenomenon as it happened – mark the first ever time that scientists have been able to watch the intense event directly in such a way.

Such events are called tidal disruptions and are incredibly rare, happening only once every 10,000 to 100,000 years in a galaxy the size of our Milky Way.

It was spotted by Nasa's Transiting Exoplanet Survey Satellite. That was sent into space to look for other worlds, but allows researchers to look at other phenomena in the universe.

TESS data let us see exactly when this destructive event, named ASASSN-19bt, started to get brighter, which we’ve never been able to do before,” said Thomas Holoien, a Carnegie Fellow at the Carnegie Observatories in Pasadena, California. “Because we identified the tidal disruption quickly with the ground-based All-Sky Automated Survey for Supernovae (ASAS-SN), we were able to trigger multiwavelength follow-up observations in the first few days.

"The early data will be incredibly helpful for modelling the physics of these outbursts.”

The event was first spotted by ASAS-SN, a worldwide network of 20 different telescopes at the beginning of the year. As it did, it sent out an alert to international astronomers, so that they could track it themselves.

Holoien received that alert and pointed two telescopes towards the incident and asked for more to look that way too.

Nasa's TESS was already looking towards the right part of space. It spends its time watching vast parts of the sky known as sectors for 27 days each, with the aim of spotting moments where stars go dark that could indicate a planet has passed in front of them.

Astronomers thought it might also be able to catch the earliest moments of flare-ups around stars, such as supernovae and tidal disruptions. And it did see this one: first spotting a week before ASAS-SN saw it, but unable to tell Earth straight away because it sends back its data once every two weeks, and that must then be processed by Nasa.

Researchers could then look back at that data and see the star as it was being torn up by the black hole.

“The early TESS data allow us to see light very close to the black hole, much closer than we’ve been able to see before,” said Patrick Vallely, a co-author and National Science Foundation Graduate Research Fellow at OSU.

“They also show us that ASASSN-19bt’s rise in brightness was very smooth, which helps us tell that the event was a tidal disruption and not another type of outburst, like from the center of a galaxy or a supernova.”

Much about tidal disruptions is still mysterious to astronomers, but observations of this kind could shed more light on why they happen. They are unclear about why they throw out so much UV emissions but so few X-rays, for instance.

“People have suggested multiple theories — perhaps the light bounces through the newly created debris and loses energy, or maybe the disk forms further from the black hole than we originally thought and the light isn’t so affected by the object’s extreme gravity,” said S. Bradley Cenko, Swift’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “More early-time observations of these events may help us answer some of these lingering questions.”

Join our commenting forum

Join thought-provoking conversations, follow other Independent readers and see their replies

Comments

Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged inPlease refresh your browser to be logged in