'Lucky' observation: Scientists watch a black hole shredding a star

'Lucky' observation: Scientists watch a black hole shredding a star
This illustration shows a tidal disruption, which occurs when a passing star gets too close to a black hole and is torn apart into a stream of gas. Some of the gas eventually settles into a structure around the black hole called an accretion disk. Credit: NASA's Goddard Space Flight Center

A NASA satellite searching space for new planets gave astronomers an unexpected glimpse at a black hole ripping a star to shreds.

It is one of the most detailed looks yet at the phenomenon, called a event (or TDE), and the first for NASA's Transiting Exoplanet Survey Satellite (more commonly called TESS.)

The milestone was reached with the help of a worldwide network of robotic telescopes headquartered at The Ohio State University called ASAS-SN (All-Sky Automated Survey for Supernovae). Astronomers from the Carnegie Observatories, Ohio State and others published their findings today in The Astrophysical Journal.

"We've been closely monitoring the regions of the sky where TESS is observing with our ASAS-SN telescopes, but we were very lucky with this event in that the patch of the sky where TESS is continuously observing is small, and in that this happened to be one of the brightest TDEs we've seen," said Patrick Vallely, a co-author of the study and National Science Foundation Graduate Research Fellow at Ohio State. "Due to the quick ASAS-SN discovery and the incredible TESS data, we were able to see this TDE much earlier than we've seen others—it gives us some new insight into how TDEs form."

Tidal disruption events happen when a star gets too close to a black hole. Depending on a number of factors, including the size of the star, the size of the black hole and how close the star is to the black hole, the black hole can either absorb the star or tear it apart into a long, spaghetti-like strand.

"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, who earned his Ph.D. at Ohio State. "Because we discovered the tidal disruption quickly with the ground-based ASAS-SN, we were able to trigger multiwavelength follow-up observations in the first few days. The early data will be incredibly helpful for modeling the physics of these outbursts."

ASAS-SN was the first system to see that a black hole was ripping a star apart. Holoien was working at the Las Campanas Observatory in Chile on Jan. 29, 2019, when he got an alert from one of ASAS-SN's robotic telescopes in South Africa. Holoien trained two Las Campanas telescopes on the tidal disruption event and then requested follow-up observations by other telescopes around the world.

TESS already happened to be monitoring the exact part of the sky where the ASAS-SN telescope discovered the tidal disruption event. It was not just good luck that the telescopes and satellite aligned—after TESS launched in July 2018, the team behind ASAS-SN devoted more of the ASAS-SN telescopes' time to the parts of the sky that TESS was observing.

When a star strays too close to a black hole, intense tides break it apart into a stream of gas. The tail of the stream escapes the system, while the rest of it swings back around, surrounding the black hole with a disk of debris. This video includes images of a tidal disruption event called ASASSN-19bt taken by NASA’s Transiting Exoplanet Survey Satellite (TESS) and Swift missions, as well as an animation showing how the event unfolded. Credit: NASA's Goddard Space Flight Center

But it was fortunate that the tidal disruption event happened in the systems' lines of sight, said Chris Kochanek, professor of astronomy at Ohio State.

Tidal disruptions are rare, occurring once every 10,000 to 100,000 years in a galaxy the size of the Milky Way. Supernovae, by comparison, happen every 100 years or so. Scientists have observed about 40 tidal disruption events throughout history (ASAS-SN sees a few per year). The events are rare, Kochanek said, mostly because stars need to be very close to a black hole—about the distance Earth is from our own sun—in order to create one.

"Imagine that you are standing on top of a skyscraper downtown, and you drop a marble off the top, and you are trying to get it to go down a hole in a manhole cover," he said. "It's harder than that."

And because ASAS-SN caught the tidal disruption event early, Holoien was able to train additional telescopes on the event, capturing a more detailed look than might have been possible before. Astronomers could then look at data from TESS—which, because it came from a satellite in space, was not available until a few weeks after the event—to see whether they could spot the event in the lead-up. Data from TESS meant that they could see signs of the tidal disruption event in data from about 10 days before it occurred.

Black hole shreds star, UH astronomer on discovery team
After passing too close to a supermassive black hole, the star in this artist's conception is torn apart into a thin stream of gas, which is then pulled back around the black hole and slams into itself, creating a bright shock and ejecting more hot material. Credit: Robin Dienel courtesy of the Carnegie Institution for Science

"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," Vallely said. "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."

Holoien's team used UV data from NASA's Neil Gehrels Swift Observatory—the earliest yet seen from a tidal disruption—to determine that the temperature dropped by about 50%, from around 71,500 to 35,500 degrees Fahrenheit (40,000 to 20,000 degrees Celsius), over a few days. It's the first time such an early temperature decrease has been seen in a tidal before, although a few theories have predicted it, Holoien said.

More typical for these kinds of events was the low level of X-ray emission seen by Swift. Scientists don't fully understand why tidal disruptions produce so much UV emission and so few X-rays.

Astronomers think the supermassive black hole that generated ASASSN-19bt weighs around 6 million times the sun's mass. It sits at the center of a galaxy called 2MASX J07001137-6602251 located around 375 million light-years away in the constellation Volans. The destroyed star may have been similar in size to our sun.


Explore further

Spinning black hole swallowing star explains superluminous event

More information: Discovery and Early Evolution of ASASSN-19bt, the First TDE Detected by TESS, Astrophysical Journal (2019). iopscience.iop.org/article/10. … 847/1538-4357/ab3c66
Journal information: Astrophysical Journal

Citation: 'Lucky' observation: Scientists watch a black hole shredding a star (2019, September 26) retrieved 17 October 2019 from https://phys.org/news/2019-09-lucky-scientists-black-hole-shredding.html
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Sep 26, 2019
TDEs are most likely 3-body events, in which a lighter companion, or massive planet, gets flung outward at high velocity, carrying away angular-momentum lost by the more massive body as it falls in.

Sep 26, 2019
TDEs are most likely 3-body events, in which a lighter companion, or massive planet, gets flung outward at high velocity, carrying away angular-momentum lost by the more massive body as it falls in.
An April draft version doesn't mention anything about that.
https://arxiv.org...9293.pdf

The released version, of course, has only the abstract outside the paywall.

Sep 26, 2019
It's probably a plasmoid ripping apart a...a...a... thingy. See? That's science for you! Yo. EU rules! :)

Sep 26, 2019
TDEs are most likely 3-body events, in which a lighter companion, or massive planet, gets flung outward at high velocity, carrying away angular-momentum lost by the more massive body as it falls in.
An April draft version doesn't mention anything about that.
https://arxiv.org...9293.pdf

The released version, of course, has only the abstract outside the paywall.


I've had a butcher's at the paper, and it is little different to the preprint. That is not to say that 4infinities is wrong. It just isn't mentioned.

Sep 27, 2019
'Lucky' observation: Scientists watch a black hole shredding a star

The title needs adjustment;

'Lucky' extrapolation: Scientists see a faint blip and build a faerie tale.

Sep 27, 2019
This can be modeled without mathematics and physics.
It's obviously an:

Electric Boogaloo Plasbarycentermoid.


Sep 27, 2019
it is very shellfish of you cant
to refuse to share your superior knowledge with the rest of us

all that alternative data you have collected from your ouiija board
that would support your mystical visions

all you need to do is come down from your lofty, shellac tower
to release your accumulated database of paraabnormal discoveries

have that body of occult work, verified, confirmed, & peer-reviewed
then released for publication

that finally!
you can sit back to await your richly deserved ignoble award!

Sep 27, 2019
it is very shellfish of you cant
to refuse to share your superior knowledge with the rest of us

Very snobfish of you willis
to imagine that you possess the capacity to distingfish superior knowledge despite your foolfishness.

Now go take your meds and give your stupidity some desperately needed rest.

Sep 27, 2019
ah aintieoral
with whom stupidity lies & lies & lies
sharing the same bed at night
& shadowing all day

Sep 28, 2019
Supermassive concentration expanding and emit dark expanding matter which expanding inside expanding star faster and faster.

After that that faster and faster expanding dark matter is expanding visible matter which brake that expanding star.

There is no pulling force.

No curving space.

Curving space is naked empire!!!


Sep 28, 2019
I mean that new expanding visible matter get expanding star own expanding matter expanding faster and thats why it pushing away from expanding star centre, that way where is expanding supermassive concentration.

Expanding space is naked empire.

Nucleus of atoms expanding and recycling dark expanding pushing force which have a nature of expanding light.

Expanding lights interactive with each other and get each other expanding faster and faster.

Thats why expanding light moving faster and faster same way what matter and light expanding.


Sep 28, 2019
Christ, this place doesn't half attract the lunatic fringe!

Sep 28, 2019

No curving space.

Curving space is naked empire!!!



Feel free to link us to your paper/s refuting all the successful tests and observations of relativity. And the findings from Gravity Probe B. We'll wait.

Sep 28, 2019
Galaxys born inside to outside.

This is something what we can see later with James Webb telescope.

Expanding supermassive concentrations born with own 3 D big bang with out pulling force.

After that expanding supermassive concentrations collide together and then born lot of new expanding stars same way how expanding supermassive concentrations born with out pulling force.

Also nucleus of atoms expanding and emit dark expanding pushing force which have example nature of expanding photons and nature of expanding electrons.


Sep 28, 2019
so, mrpus,
all those times you fall over?
you are claiming that you are falling upwards into the sky?

sounds to me you are suffering from a string of concussions
leaving you unable to tell which way is up or down

too bad you have such a negligent caretaker
who is so careless about making you wear your protective helmet when you leave your asylum bunk in the morning

you have obviously clonked your noggin pretty hard, too many times

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