Name: 我們首次看到一顆新生的超新星？| 科學秀新聞 (Our First Glimpse of a Newborn Supernova? | SciShow News)
Uploaded: 2021-01-14T10:29:01.000Z
Duration: 5 min 4 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Supernovas are some of the most powerful explosions in existence.

Certain types also involve some of the most massive stars,

which leave behind dense cores of their former selves,

either super-compact neutron stars or black holes.

On Earth, we capture the light of supernovas all the time.

But we've never seen the exact moment the star collapses into its remnant.

Last week, at the 233rd meeting of the American Astronomical Society, astronomers announced

that they'd spotted what they think was a supernova just as it was beginning to explode.

In June 2018, a mysterious signal from 200 million light years away reached the ATLAS telescopes in Hawaii.

It received the catalog name AT2018cow, so naturally astronomers are calling it “the Cow”.

At first, it was just ID'd as a super bright, transient phenomenon.

It didn't quite match what we'd seen in other supernova data,

it was much brighter and shorter-lived, expending most of its energy in just a couple weeks.

Researchers had a few different ideas about what it might be,

like an explosion causedby a black hole eating a white dwarf star, or a shockwave generated by something else.

So they continued monitoring it even after it had started to fade,

combining data from multiple wavelengths of light using telescopes around the world.

And eventually, they concluded it was most likely the death throes of a massive star.

It might even be a blue supergiant star that actually failed to explode,

but had its core collapse into  a black hole anyway.

Now, a lot of news outlets are selling this as way more definite,

that we've definitely just witnessed the birth of a black hole or neutron star.

The reality is much less certain, and some astronomers still think it could be one of those other hypotheses.

But if the Cow does turn out to be a core-collapse supernova,

it's the first time we've ever observed the birth of a supernova remnant.

It's also the first time we've really observed a baby remnant in so many different types of light,

from radio waves all the way to gamma rays.

That initial bright glow was probably caused by some of the star's outer matter spiraling down toward

its newly-formed black hole or neutron star.

There was also matter shooting away from it at 10 percent of the speed of light.

One reason astronomers could get such a good look was that there wasn't a lot of material blocking the center,

the Cow didn't eject nearly as much stellar gas while its core collapsed as other stars do.

It's also way closer than any similar-looking events we've seen,

ATLAS spotted it just from its usual nightly scan of the sky.

Astronomers plan to do follow-up studies to look for similar events with other telescopes.

But in the meantime, the universe just did a magnificent experiment and we got to watch

and now we've got a lot of data to analyze.

And that's not the only first astronomers announced recently.

A paper published this week in the journal Nature Astronomy describes

the very first binary star system we've seen where the stars orbit each other

in basically the opposite direction as the disk of dust and matter that will one day form planets.

Not opposite in terms of backwards, but perpendicular!

So while the stars are orbiting each other like this, the disk is rotating like this.

Astronomers get glimpses of protoplanetary disks all the time,

they're super important for learning about how solar systems form,

and give us hints about how ours could have formed.

This isn't the first time we've found planets orbiting a binary star system, either.

But until now, the idea that a disk could orbit its parent stars

in a perpendicular plane was entirely theoretical.

Now that we've found an example in the real world, or I guess in the real universe,

they could turn out to be relatively common.

Astronomers used the  Atacama Large Millimeter/Submillimeter Array  down in Chile to observe the binary system

which is known as HD 98800BaBb, which we've known about since the 1980s.

Specifically, this group measured the changes in certain wavelengths of light emitted by

both the disk and the stars as they orbited each other.

And when they calculated how each component was moving with respect to Earth,

they concluded that the orientation that best fit the data was that perpendicular setup.

According to the lead author of the paper, the most exciting thing about this discovery

is that this so-far unique protoplanetary disk is basically identical to those around a single star system,

The researchers weren't able to confirm the presence of actual planets in the disk,

but there is a bit of evidence that suggests the disk is taking its first steps toward making some.

So, from these strange little baby planets to that newborn supernova remnant,

it's been an awesome couple of weeks for watching the birth of new things way out there in the universe.

Thanks for watching this episode of SciShow Space News!

If you want to stay up to date on amazing new discoveries like these

or learn about some of the most incredible things in existence,

Just go to youtube.com/scishowspace and subscribe!