When Dead Stars Collide!

When Dead Stars Collide!

Gravity has been making waves - literally.  Earlier this month, the Nobel Prize in Physics was awarded for the first direct detection of gravitational waves two years ago. But astronomers just announced another huge advance in the field of gravitational waves - for the first time, we’ve observed light and gravitational waves from the same source.

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There was a pair of orbiting neutron stars in a galaxy (called NGC 4993). Neutron stars are the crushed leftover cores of massive stars (stars more than 8 times the mass of our sun) that long ago exploded as supernovas. There are many such pairs of binaries in this galaxy, and in all the galaxies we can see, but something special was about to happen to this particular pair.

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Each time these neutron stars orbited, they would lose a teeny bit of gravitational energy to gravitational waves. Gravitational waves are disturbances in space-time - the very fabric of the universe - that travel at the speed of light. The waves are emitted by any mass that is changing speed or direction, like this pair of orbiting neutron stars. However, the gravitational waves are very faint unless the neutron stars are very close and orbiting around each other very fast.

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As luck would have it, the teeny energy loss caused the two neutron stars to get a teeny bit closer to each other and orbit a teeny bit faster.  After hundreds of millions of years, all those teeny bits added up, and the neutron stars were *very* close. So close that … BOOM! … they collided. And we witnessed it on Earth on August 17, 2017.  

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Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

A couple of very cool things happened in that collision - and we expect they happen in all such neutron star collisions. Just before the neutron stars collided, the gravitational waves were strong enough and at just the right frequency that the National Science Foundation (NSF)’s Laser Interferometer Gravitational-Wave Observatory (LIGO) and European Gravitational Observatory’s Virgo could detect them. Just after the collision, those waves quickly faded out because there are no longer two things orbiting around each other!

LIGO is a ground-based detector waiting for gravitational waves to pass through its facilities on Earth. When it is active, it can detect them from almost anywhere in space.

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The other thing that happened was what we call a gamma-ray burst. When they get very close, the neutron stars break apart and create a spectacular, but short, explosion. For a couple of seconds, our Fermi Gamma-ray Telescope saw gamma-rays from that explosion. Fermi’s Gamma-ray Burst Monitor is one of our eyes on the sky, looking out for such bursts of gamma-rays that scientists want to catch as soon as they’re happening.

And those gamma-rays came just 1.7 seconds after the gravitational wave signal. The galaxy this occurred in is 130 million light-years away, so the light and gravitational waves were traveling for 130 million years before we detected them.

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After that initial burst of gamma-rays, the debris from the explosion continued to glow, fading as it expanded outward. Our Swift, Hubble, Chandra and Spitzer telescopes, along with a number of ground-based observers, were poised to look at this afterglow from the explosion in ultraviolet, optical, X-ray and infrared light. Such coordination between satellites is something that we’ve been doing with our international partners for decades, so we catch events like this one as quickly as possible and in as many wavelengths as possible.

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Astronomers have thought that neutron star mergers were the cause of one type of gamma-ray burst - a short gamma-ray burst, like the one they observed on August 17. It wasn’t until we could combine the data from our satellites with the information from LIGO/Virgo that we could confirm this directly.

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This event begins a new chapter in astronomy. For centuries, light was the only way we could learn about our universe. Now, we’ve opened up a whole new window into the study of neutron stars and black holes. This means we can see things we could not detect before.

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The first LIGO detection was of a pair of merging black holes. Mergers like that may be happening as often as once a month across the universe, but they do not produce much light because there’s little to nothing left around the black hole to emit light. In that case, gravitational waves were the only way to detect the merger.

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Image Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

The neutron star merger, though, has plenty of material to emit light. By combining different kinds of light with gravitational waves, we are learning how matter behaves in the most extreme environments. We are learning more about how the gravitational wave information fits with what we already know from light - and in the process we’re solving some long-standing mysteries!

Want to know more? Get more information HERE.

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More Posts from Maevetheeuropan and Others

8 years ago
The Exoplanetary Menagerie

The Exoplanetary Menagerie

Today a massive discovery was announced: 39 light years away in the TRAPPIST-1 star system seven terrestrial planets all orbit extremely close to each other.

…and three are well within their star’s “habitable zone”.

TRAPPIST-1 is an ultra-cool dwarf star. Because its temperature is so much lower than a typical star like the sun (it’s roughly 2550 K while the sun’s 5772 K) planets are able to orbit much closer than they could in our Solar System and sustain habitable conditions. All seven of the discovered exoplanets orbit closer to TRAPPIST-1 than Mercury does to the sun.

Of the different planets discovered, one is immensely Earthlike, having a similar size and receiving roughly the same amount of light as Earth. This place could be a whole lot more like home than anything we’ve found yet. Another planet is a potential water-world, getting about as much light as does Mars (with an atmosphere, yes, it could be a liquid water world).

So close do these planets all orbit near to each other that if you were to go to one and look up, you could see the other planets in the sky above you… and they’d be as big as *or larger than the Moon is in our sky*. It must be one of the most beautiful sights.

So what’s the big deal right? NASA’s already found over 3000 exoplanets - what makes these ones special?

A few remarkable things:

One, TRAPPIST-1 is a member of the M-class stars - stars which make up 70% or so of all the stars out in the Milky Way. Knowing that such stars can host magnificent habitable planetary systems means the search for life just got blown wide open to 70% of the stars in our galaxy.

Two, though 39 light years seems far, this is actually unimaginably close. We’re basically neighbors. The fact that TRAPPIST-1 is so close means that astronomers will be able to subject this place to decades of intense research.

As NASA begins to turn space telescopes such as Hubble, Kepler and Spitzer on TRAPPIST-1, I think we’ll be hearing a lot more from it soon.

Before you go, please consider joining the Planetary Society. If TRAPPIST-1 intrigues you, just wait until you see what else we have happening. 

At the Planetary Society we have a radio show with some of the most groundbreaking material to include exoplanet hunters, engineers designing interstellar missions and interviews with astronauts. Most important though, we go to D.C. and make sure the politicians continue funding NASA and space science, and we reach out to people and try to show them what could be.

On that note, here are some artist conceptions of the TRAPPIST-1 star system and what could be:

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So good job to the team that made this discovery (especially lead author Michaël Gillon) and I can’t wait to learn more about this place soon.

(Image credit: NASA-JPL/Caltech, NASA/JPL-Caltech/R. Hurt (IPAC), NASA/JPL-Caltech/T. Pyle (IPAC), NASA/JPL-Caltech/R. Hurt (IPAC), ESO/M. Kornmesser and NASA-JPL/Caltech respectively)

8 years ago
This Tea Could Help Humans Conquer Mars l VICE l Munchies
Synthetic biology researchers at Imperial College London have manipulated the bacteria in kombucha tea to engineer material for building shelters on Mars.

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8 years ago

For American science, the next four years look to be challenging. The newly inaugurated President Trump, and many of his Cabinet picks, have repeatedly cast doubt upon the reality of human-made climate change, questioned the repeatedly proven safety of vaccines. Since the inauguration, the administration has already frozen grants and contracts by the Environmental Protection Agency and gagged researchers at the US Department of Agriculture. Many scientists are asking themselves: What can I do?

And the answer from a newly formed group called 314 Action is: Get elected.

For American Science, The Next Four Years Look To Be Challenging. The Newly Inaugurated President Trump,

The organization, named after the first three digits of pi, is a political action committee that was created to support scientists in running for office. It’s the science version of Emily’s List, which focuses on pro-choice female candidates, or VoteVets, which backs war veterans. “A lot of scientists traditionally feel that science is above politics but we’re seeing that politics is not above getting involved in science,” says founder Shaughnessy Naughton. 

“We’re losing, and the only way to stop that is to get more people with scientific backgrounds at the table.”

(Continue Reading)


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8 years ago
Two Very alarming Changes Have Already Been Made On The White House Website. Reason, Empathy And Progress
Two Very alarming Changes Have Already Been Made On The White House Website. Reason, Empathy And Progress
Two Very alarming Changes Have Already Been Made On The White House Website. Reason, Empathy And Progress

Two very alarming changes have already been made on the White House website. Reason, empathy and progress must be fought for. I hope this isn’t indicative of upcoming policies but fear it obviously is.

Also I just edited this post to add my own screenshot: the White House’s website for combating antibiotic resistant bacteria is gone too.

I want to note that most of the great steps of social progress in American history were *not* made by presidents or politicians acting of their own accord. America thrives in a state of constant *peaceful* revolt. Protest, political dissent and civil disobedience are what change things.

Voting is great and we need more to do it, but the women’s suffrage movement didn’t get voted into victory. Republican President Nixon (Nixon!) didn’t create the Environmental Protection Agency because he had an environmentalist’s stance on the Earth.

It’s important to always remember that when people wield their concerns and press power to answer for itself, they change the world.

(Images courtesy of screenshots from a friend and from myself)

8 years ago

When Can I Die on Mars? 

Elon Musk recently announced SpaceX’s plans to send a spacecraft to the surface of Mars by 2018. It’s never been easier to die on Mars.

By: Fraser Cain. Support Universe Today on Patreon


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8 years ago

HUGE ANNOUNCEMENT!

Elon Musk is set to announce his plans for Mars colonization in an hour, at 2:30 Eastern Time. 

Please watch it because this could be history in the making.


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8 years ago
Glittering Frisbee Galaxy: This Image From Hubble’s Shows A Section Of A Spiral Galaxy Located About

Glittering Frisbee Galaxy: This image from Hubble’s shows a section of a spiral galaxy located about 50 million light-years from Earth. We tend to think of spiral galaxies as massive and roughly circular celestial bodies, so this glittering oval does not immediately appear to fit the visual bill. What’s going on? Imagine a spiral galaxy as a circular frisbee spinning gently in space. When we see it face on, our observations reveal a spectacular amount of detail and structure. However, the galaxy frisbee is very nearly edge-on with respect to Earth, giving it an appearance that is more oval than circular. The spiral arms, which curve out from the galaxy’s dense core, can just about be seen. Although spiral galaxies might appear static with their picturesque shapes frozen in space, this is very far from the truth. The stars in these dramatic spiral configurations are constantly moving as they orbit around the galaxy’s core, with those on the inside making the orbit faster than those sitting further out. This makes the formation and continued existence of a spiral galaxy’s arms something of a cosmic puzzle, because the arms wrapped around the spinning core should become wound tighter and tighter as time goes on - but this is not what we see. This is known as the winding problem. Image credit: ESA/Hubble & NASA For more information on this image, visit: https://go.nasa.gov/2niODGL

7 years ago
A solar eclipse is coming to America. Here’s what you’ll see where you live.
On Monday August 21, a solar eclipse will cut across the entire United States. And wherever you are, you will be able to see it. Even though the "totality" — the area where the sun is completely...
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maevetheeuropan - Maeve the Europan
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