Podcaster: Richard Drumm
Title: Space Scoop: Beaming with the Light of Millions of Suns
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://www.unawe.org/kids/unawe1806/
Description: Space scoop, news for children.
In the 1980s, scientists started discovering a new type of object in other galaxies, objects that were extremely bright in X-rays. When looked at with X-ray telescopes, they shone as bright as a million suns combined.
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — Helge Bjørkhaug, one of our Patreon supporters.
Big thanks to our Patreon supporters this month: Brett Duane, Joseph J. Biernat, Nik Whitehead, Timo Sievänen, Noel Ruppenthal, Steven Jansen, Casey Carlile, Phyllis Simon Foster
Transcript:
This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
Beaming with the Light of Millions of Suns
If our eyes could see super-energetic types of light like X-rays, looking at our friends would be a weird experience. We’d be able to see straight through their skin to their bones underneath!
Provided, that is, that there was a source of X-rays to illuminate them.
Really, we’re lucky we don’t have that super power, it wouldn’t be of much use evolutionarily anyway. However there are lots of benefits to looking at X-rays coming from objects in space using X-ray telescopes.
Most X-rays come from extremely hot objects with temperatures up to hundreds of millions of degrees, including the Sun, exploded stars and feeding black holes!
In the 1980s, scientists started discovering a new type of object in other galaxies, objects that were extremely bright in X-rays. When looked at with X-ray telescopes, they shone as bright as a million suns combined.
They’re called ULXs, Ultra Luminous X-ray sources. Somewhere between 150 and 200 of them have been found in the Universe, so they’re somewhat rare. Especially when you consider that the Milky Way galaxy alone has hundreds of billions of stars.
At first, scientists thought that all these cosmic objects were feeding black holes, but recent studies revealed that a few are actually something more interesting.
In 2014, astronomers using NASA’s NuSTAR, the Nuclear Spectroscopic Telescope Array and the Chandra X-ray Observatory found out that 4 of the ULXs are actually the result of neutron stars.
The 4 ULXs had regular variations in X-ray brightness, or pulsations.
This is something we see in a neutron star but not a black hole.
The pulsations weren’t the only thing the astronomers found.
There was a dip in the spectrum of X-ray energies at 4.5 kilo electron volts (keV) that is the result of a process called cyclotron resonance scattering.
The size of the dip in the X-ray spectrum implies a magnetic field strength that is a second, independent line of strong evidence that these 4 ULXs are a result of a neutron star and not a stellar mass black hole.
The latest of the 4 neutron star ULXs to be discovered, called ULX8, is in M51, the Whirlpool Galaxy, near Ursa Major in the constellation Canes Venatici, the hunting dogs.
In historical astronomical illustrations the hunting dogs belong to Boötes, the herdsman, and are chasing Ursa Major, presumably to protect the herdsman’s herd from the great bear.
Neutron stars are the burnt-out, left-over cores of massive stars that have exploded as supernovae. They’re extremely dense objects, containing more mass than our Sun but squashed into a sphere the size of a city!
Like black holes, neutron stars have ultra-strong gravity that can pull material away from nearby stars. As this material falls toward the neutron star, it heats up and begins to glow with X-rays.
As more and more material falls onto the neutron star, there comes a point where the X-ray light becomes so intense that it actually pushes the infalling material away.
At this point the star shouldn’t be able to gather more material any faster or grow any brighter. But the newly discovered type of neutron star has found a way to break this so-called Eddington Limit!
“In the same way that we can only eat so much food at a time, there are limits to how fast neutron stars can gather material,” said Murray Brightman, a CalTech scientist on the new study, published in the journal Nature Astronomy.
“But these objects are somehow breaking this limit to shine so incredibly bright in X-rays, and we don’t know why.”
So clearly there is more work to be done to explain the physics of what’s going on here.
Hey Here’s A Cool Fact:
In a way, neutron stars are actually more similar to planets than stars. They aren’t gassy balls of plasma any more and are the size of small planets and can actually have a solid crust. Some scientists think that neutron star crust is around 10 billion times as strong as steel.
The so-called baryonic matter that you & I are made of is mostly empty space. This is how neutrinos can sail right through the whole Earth without even noticing that we’re here!
When a medium-large star goes supernova, the intense pressure & temperature causes the electrons to fuse with protons and form neutrons.
Effectively one of the 3 quarks, an up quark, in the proton flips, so-to-speak, into a down quark and turns the particle into a neutron. The up-up-down quarks that make up the proton becomes the up-down-down quark composition of a neutron.
It’s WAY more complicated than that makes it seem, but that’s the simplified version of the electron capture that takes place.
Thus the star’s core is now basically one big ball of neutrons and there’s only the neutron degeneracy pressure to hold the core from further collapse into a black hole.
The neutrons can almost touch each other & pack very tightly. No more empty space. The densities are unimaginable! A teaspoon full of neutron star material would weigh a billion tons!
If you had that teaspoonful of neutrons it would immediately fall from your hand and push through the Earth’s crust & go straight to the center of our core.
In the Marvel Studio movies, Thor’s hammer is supposed to be made of neutronium, the degenerate neutron “gas” that makes up a neutron star.
In the 2011 movie “Thor”, Odin says that Mjolnir, or “Grinder”, the hammer of Thor, was forged in the heart of a dying star.
Considering that according to the story, no living being may lift the hammer unless they are worthy, this sounds about right. An insanely massive hammer.
What do you think?
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
=====================
The 365 Days of Astronomy Podcast is produced by Astronomical Society of the Pacific. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrates the Year of Everyday Astronomers as we embrace Amateur Astronomer contributions and the importance of citizen science. Join us and share your story. Until tomorrow! Goodbye!