What's A Neutron Star? I Read About Them In Bill Bryson's Book, But I Couldn't Figure Out Why A Neutron

Neutron Stars Collide

The recent detection of two neutron stars colliding has sent waves through spacetime and the astronomical community.

You may have seen headlines in the news and not really know why this is such a big deal.

Here’s the Sparknotes version:

A while back a thing called “gravitational waves” were observed for the first time. These are fluctuations in the fabric of spacetime that propagate out from their source just like light, i.e. radially/like a pebble dropped in water. General relativity shows us that the acceleration of objects with mass cause this event to occur.

Until fairly recently these have been too difficult to observe and in fact Einstein didn’t think we’d ever be able to. A series of laser interferometers have disproved that assumption. Using high-precision analysis of how the lasers shift as a gravitational wave moves through them scientists can now see the small movements in the universe that are gravitational waves.

Importantly, we now have three such observatories capable of working together. Known as the “LIGO-Virgo” team, two observatories in the U.S. and one in Italy detected these shifting in spacetime. Three is a pretty magical number in coordinating detections like this because you can then triangulate where the signal comes from and…

BINGO! Within hours optical observatories were zeroing in on the predicted source of these spacetime fluctuations. Indeed, they confirmed the presence of a previously unseen glow:

What you’re looking at is the glow of two neutron stars colliding into each other. This explosion has the energy of approximately 260,000,000 suns.

Each of these stars has such a large mass that the waves in spacetime are actually detectable from a distance of 140 million light-years away.

Impressive, right? Although you might agree, this still begs the question of what exactly we’ve learned from this event. Well - a lot. Since this is the first observation we have made with both gravitational wave observatories and more traditional astronomical observatories (i.e. light detecting ones) we’ve been able to put some numbers on the phenomenon. Here are some of the things we’ve learned:

1) Gravitational waves propagate at the speed of light!

2) A huge portion of heavier elements (like gold and uranium!) may have their origins in neutron star collisions! Nuclear synthesis in stars more typical like the sun is restricted to closer to 10% of the star’s mass being able to fuse elements together into new ones. This process is actually quite inefficient (actually, YOU are a more efficient radiator than the sun!) and it becomes more difficult for a star to fuse the heavier elements. Before this event we didn’t have a good way of explaining why we found so much more heavy stuff than stellar nuclear synthesis could account for. Now? Baboom! This neutron star collision resulted in the synthesis of so much gold that it’s about 150 times more massive than the Earth! Cha-Ching!

So if you’re an amateur (or professional, I suppose) astronomer and you want to see this collision, now dubbed GW170817, and you build a little radio telescope (another post!), you’ll be able to detect this collision for the next 5-10 years due to the afterglow.

(Image credit: NASA and ESA)

Pls tell me interesting facts about stars

Interesting facts about stars:

Heavy stars blow up and make heavier elements like gold. So, every bit of gold you’ve ever seen, worn, or touched came from the dying explosion of a star. Other elements made in supernovae include anything on the periodic table heavier than iron

Heavy stars blow up when they start fusing iron. Meaning, the iron in your frying pan, car, and your blood killed a star at least 3 times the mass of the sun.

Some massive stars that die end up compressing all their mass into a star about 6 miles across, or about the size of a city. This is called a neutron star.

To put this in perspective, these stars start out 3 times as big as our sun and all of their mass is crushed into something the size of a city. The space between atoms is squished away, and the protons and electrons combine to form neutrons. 

Neutron stars are literally as dense as atomic nuclei

Most stars come in pairs

The most common stellar type is a red dwarf, which is a small, red, dim, cool star.

Honestly, that’s just the first few that come to mind, space is really crazy.

Black holes ruled out as universe's missing dark matter

For one brief shining moment after the 2015 detection of gravitational waves from colliding black holes, astronomers held out hope that the universe’s mysterious dark matter might consist of a plenitude of black holes sprinkled throughout the universe.

University of California, Berkeley, physicists have dashed those hopes.

Based on a statistical analysis of 740 of the brightest supernovas discovered as of 2014, and the fact that none of them appear to be magnified or brightened by hidden black hole “gravitational lenses,” the researchers concluded that primordial black holes can make up no more than about 40 percent of the dark matter in the universe. Primordial black holes could only have been created within the first milliseconds of the Big Bang as regions of the universe with a concentrated mass tens or hundreds of times that of the sun collapsed into objects a hundred kilometers across.

The results suggest that none of the universe’s dark matter consists of heavy black holes, or any similar object, including massive compact halo objects, so-called MACHOs.

Keep reading

Unveiling the Center of Our Milky Way Galaxy

We captured an extremely crisp infrared image of the center of our Milky Way galaxy. Spanning more than 600 light-years, this panorama reveals details within the dense swirls of gas and dust in high resolution, opening the door to future research into how massive stars are forming and what’s feeding the supermassive black hole at our galaxy’s core.

Among the features coming into focus are the jutting curves of the Arches Cluster containing the densest concentration of stars in our galaxy, as well as the Quintuplet Cluster with stars a million times brighter than our Sun. Our galaxy’s black hole takes shape with a glimpse of the fiery-looking ring of gas surrounding it.

The new view was made by the world’s largest airborne telescope, the Stratospheric Observatory for Infrared Astronomy, or SOFIA.

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Extinct tree grows anew from ancient jar of seeds unearthed by archaeologists

by Stephen Messenger

“For thousands of years, Judean date palm trees were one of the most recognizable and welcome sights for people living in the Middle East — widely cultivated throughout the region for their sweet fruit, and for the cool shade they offered from the blazing desert sun.

From its founding some 3,000 years ago, to the dawn of the Common Era, the trees became a staple crop in the Kingdom of Judea, even garnering several shout-outs in the Old Testament. Judean palm trees would come to serve as one of the kingdom’s chief symbols of good fortune; King David named his daughter, Tamar, after the plant’s name in Hebrew.

By the time the Roman Empire sought to usurp control of the kingdom in 70 AD, broad forests of these trees flourished as a staple crop to the Judean economy — a fact that made them a prime resource for the invading army to destroy. Sadly, around the year 500 AD, the once plentiful palm had been completely wiped out, driven to extinction for the sake of conquest.

In the centuries that followed, first-hand knowledge of the tree slipped from memory to legend. Up until recently, that is.

During excavations at the site of Herod the Great’s palace in Israel in the early 1960’s, archeologists unearthed a small stockpile of seeds stowed in a clay jar dating back 2,000 years. For the next four decades, the ancient seeds were kept in a drawer at Tel Aviv’s Bar-Ilan University. But then, in 2005, botanical researcher Elaine Solowey decided to plant one and see what, if anything, would sprout.

“I assumed the food in the seed would be no good after all that time. How could it be?“ said Solowey. She was soon proven wrong.

Amazingly, the multi-millennial seed did indeed sprout — producing a sapling no one had seen in centuries, becoming the oldest known tree seed to germinate.

Today, the living archeological treasure continues to grow and thrive; In 2011, it even produced its first flower — a heartening sign that the ancient survivor was eager to reproduce. It has been proposed that the tree be cross-bred with closely related palm types, but it would likely take years for it to begin producing any of its famed fruits. Meanwhile, Solowey is working to revive other age-old trees from their long dormancy.”

***Does anyone in the know have any comments?

(Source: Tree Hugger)

Gamma-ray Bursts: Black Hole Birth Announcements

Gamma-ray bursts are the brightest, most violent explosions in the universe, but they can be surprisingly tricky to detect. Our eyes can’t see them because they are tuned to just a limited portion of the types of light that exist, but thanks to technology, we can even see the highest-energy form of light in the cosmos — gamma rays.

So how did we discover gamma-ray bursts? 

Accidentally!

We didn’t actually develop gamma-ray detectors to peer at the universe — we were keeping an eye on our neighbors! During the Cold War, the United States and the former Soviet Union both signed the Nuclear Test Ban Treaty of 1963 that stated neither nation would test nuclear weapons in space. Just one week later, the US launched the first Vela satellite to ensure the treaty wasn’t being violated. What they saw instead were gamma-ray events happening out in the cosmos!

Things Going Bump in the Cosmos

Each of these gamma-ray events, dubbed “gamma-ray bursts” or GRBs, lasted such a short time that information was very difficult to gather. For decades their origins, locations and causes remained a cosmic mystery, but in recent years we’ve been able to figure out a lot about GRBs. They come in two flavors: short-duration (less than two seconds) and long-duration (two seconds or more). Short and long bursts seem to be caused by different cosmic events, but the end result is thought to be the birth of a black hole.

Short GRBs are created by binary neutron star mergers. Neutron stars are the superdense leftover cores of really massive stars that have gone supernova. When two of them crash together (long after they’ve gone supernova) the collision releases a spectacular amount of energy before producing a black hole. Astronomers suspect something similar may occur in a merger between a neutron star and an already-existing black hole.

Long GRBs account for most of the bursts we see and can be created when an extremely massive star goes supernova and launches jets of material at nearly the speed of light (though not every supernova will produce a GRB). They can last just a few seconds or several minutes, though some extremely long GRBs have been known to last for hours!

A Gamma-Ray Burst a Day Sends Waves of Light Our Way!

Our Fermi Gamma-ray Space Telescope detects a GRB nearly every day, but there are actually many more happening — we just can’t see them! In a GRB, the gamma rays are shot out in a narrow beam. We have to be lined up just right in order to detect them, because not all bursts are beamed toward us — when we see one it’s because we’re looking right down the barrel of the gamma-ray gun. Scientists estimate that there are at least 50 times more GRBs happening each day than we detect!

So what’s left after a GRB — just a solitary black hole? Since GRBs usually last only a matter of seconds, it’s very difficult to study them in-depth. Fortunately, each one leaves an afterglow that can last for hours or even years in extreme cases. Afterglows are created when the GRB jets run into material surrounding the star. Because that material slows the jets down, we see lower-energy light, like X-rays and radio waves, that can take a while to fade. Afterglows are so important in helping us understand more about GRBs that our Neil Gehrels Swift Observatory was specifically designed to study them!

Last fall, we had the opportunity to learn even more from a gamma-ray burst than usual! From 130 million light-years away, Fermi witnessed a pair of neutron stars collide, creating a spectacular short GRB. What made this burst extra special was the fact that ground-based gravitational wave detectors LIGO and Virgo caught the same event, linking light and gravitational waves to the same source for the first time ever!

For over 10 years now, Fermi has been exploring the gamma-ray universe. Thanks to Fermi, scientists are learning more about the fundamental physics of the cosmos, from dark matter to the nature of space-time and beyond. Discover more about how we’ll be celebrating Fermi’s achievements all year!

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This first image from NASA’s James Webb Space Telescope is the deepest and sharpest infrared image of the distant universe to date. Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. Thousands of galaxies – including the faintest objects ever observed in the infrared – have appeared in Webb’s view for the first time. This slice of the vast universe covers a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground.

Pick Your Favorite Findings From Fermi’s First Decade

The Fermi Gamma-ray Space Telescope has been observing some of the most extreme objects and events in the universe — from supermassive black holes to merging neutron stars and thunderstorms — for 10 years. Fermi studies the cosmos using gamma rays, the highest-energy form of light, and has discovered thousands of new phenomena for scientists.

Here are a few of our favorite Fermi discoveries, pick your favorite in the first round of our “Fermi Science Playoff.” 

Colliding Neutron Stars

In 2017, Fermi detected a gamma ray burst at nearly the same moment ground observatories detected gravitational waves from two merging neutron stars. This was the first time light and ripples in space-time were detected from the same source.

The Sun and Moon in Gamma Rays

In 2016, Fermi showed the Moon is brighter in gamma rays than the Sun. Because the Moon doesn’t have a magnetic field, the surface is constantly pelted from all directions by cosmic rays. These produce gamma rays when they run into other particles, causing a full-Moon gamma-ray glow.

Record Rare from a Blazar

The supermassive black hole at the center of the galaxy 3C 279 weighs a billion times the mass of our Sun. In June 2015, this blazar became the brightest gamma-ray source in the sky due to a record-setting flare.

The First Gamma-Ray Pulsar in Another Galaxy

In 2015, for the first time, Fermi discovered a gamma-ray pulsar, a kind of rapidly spinning superdense star, in a galaxy outside our own. The object, located on the outskirts of the Tarantula Nebula, also set the record for the most luminous gamma-ray pulsar we’ve seen so far.

A Gamma-Ray Cycle in Another Galaxy

Many galaxies, including our own, have black holes at their centers. In active galaxies, dust and gas fall into and “feed” the black hole, releasing light and heat. In 2015 for the first time, scientists using Fermi data found hints that a galaxy called PG 1553+113 has a years-long gamma-ray emission cycle. They’re not sure what causes this cycle, but one exciting possibility is that the galaxy has a second supermassive black hole that causes periodic changes in what the first is eating.

Gamma Rays from Novae

A nova is a fairly common, short-lived kind of explosion on the surface of a white dwarf, a type of compact star not much larger than Earth. In 2014, Fermi observed several novae and found that they almost always produce gamma-rays, giving scientists a new type of source to explore further with the telescope.

A Record-Setting Cosmic Blast

Gamma-ray bursts are the most luminous explosions in the universe. In 2013, Fermi spotted the brightest burst it’s seen so far in the constellation Leo. In the first three seconds alone, the burst, called GRB 130427A, was brighter than any other burst seen before it. This record has yet to be shattered.

Cosmic Rays from Supernova Leftovers

Cosmic rays are particles that travel across the cosmos at nearly the speed of light. They are hard to track back to their source because they veer off course every time they encounter a magnetic field. In 2013, Fermi showed that these particles reach their incredible speed in the shockwaves of supernova remains — a theory proposed in 1949 by the satellite’s namesake, the Italian-American physicist Enrico Fermi.

Discovery of a Transformer Pulsar

In 2013, the pulsar in a binary star system called AY Sextanis switched from radio emissions to high-energy gamma rays. Scientists think the change reflects erratic interaction between the two stars in the binary.

Gamma-Ray Measurement of a Gravitational Lens

A gravitational lens is a kind of natural cosmic telescope that occurs when a massive object in space bends and amplifies light from another, more distant object. In 2012, Fermi used gamma rays to observe a spiral galaxy 4.03 billion light-years away bending light coming from a source 4.35 billion light-years away.

New Limits on Dark Matter

We can directly observe only 20 percent of the matter in the universe. The rest is invisible to telescopes and is called dark matter — and we’re not quite sure what it is. In 2012, Fermi helped place new limits on the properties of dark matter, essentially narrowing the field of possible particles that can describe what dark matter is.

‘Superflares’ in the Crab Nebula

The Crab Nebula supernova remnant is one of the most-studied targets in the sky — we’ve been looking at it for almost a thousand years! In 2011, Fermi saw it erupt in a flare five times more powerful than any previously seen from the object. Scientists calculate the electrons in this eruption are 100 times more energetic than what we can achieve with particle accelerators on Earth.

Thunderstorms Hurling Antimatter into Space

Terrestrial gamma-ray flashes are created by thunderstorms. In 2011, Fermi scientists announced the satellite had detected beams of antimatter above thunderstorms, which they think are a byproduct of gamma-ray flashes.

Giant Gamma-Ray Bubbles in the Milky Way

Using data from Fermi in 2010, scientists discovered a pair of “bubbles” emerging from above and below the Milky Way. These enormous bubbles are half the length of the Milky Way and were probably created by our galaxy’s supermassive black hole only a few million years ago.

Hint of Starquakes in a Magnetar

Neutron stars have magnetic fields trillions of times stronger than Earth’s. Magnetars are neutron stars with magnetic fields 1,000 times stronger still. In 2009, Fermi saw a storm of gamma-ray bursts from a magnetar called SGR J1550-5418, which scientists think were related to seismic waves rippling across its surface.

A Dark Pulsar

We observe many pulsars using radio waves, visible light or X-rays. In 2008, Fermi found the first gamma-ray only pulsar in a supernova remnant called CTA 1. We think that the “beam” of gamma rays we see from CTA 1 is much wider than the beam of other types of light from that pulsar. Those other beams never sweep across our vision — only the gamma-rays.

Have a favorite Fermi discovery or want to learn more? Cast your vote in the first of four rounds of the Fermi Science Playoff to help rank Fermi’s findings. Or follow along as we celebrate the mission all year.

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Your fave is problematic: Neutron Stars

Neutron stars are probably one of the weirdest type of objects to exist in the universe… but first let me explain what a neutron star is

when a star with the mass of 8-20 times of the sun dies (and by dies I mean fucking explodes), the core collapses to form a neutron star

they are incredibly dense, spin rapidly and have very strong magnetic fields

sounds all fun and games, right? sounds normal? well listen up

So, we know that electrons usually refuse to be squeezed together. but in a death event of a big star, the pressure is so extreme that protons and electrons get violently SMASHED together and form neutrons. 

sounds like someone needs to take an anti-agression class if you ask me

Now, what once was a star more massive than the Sun, is condensed to a tiny ball (usually about 10-20km!) of neutrons, with all of the mass in this tiny ball. 

To visualize, imagine the mass of the Sun (300 000X the mass of the Earth), in a little 20km sphere, the size of a small city.

To visualize the density of a neutron star, think of the classic model of the atom. if an atom was a sports field 100m across, it would be mostly empty. almost all of the atom’s mass sits in the core, in this example, the core is the size of a marble.

but in a neutron star, this doesn’t apply anymore. in a neutron star, the entire stadium would be filled to the brim with neutrons. ALL. OF. IT.

a single cubic centimetre of Neutronium has the mass of 400 million tons. that’s the total mass of every single car and truck in the US.

the typical gravity of a neutron star is about 100 million times of that of the Earth. clingy as shit

so far, we have detected over 1000 of these weird fucks in our galaxy alone. yikes

some Neutron stars are vampires. They can be in a binary star system where a normal star orbits them and they feed of that material

summary: extremely weird and violent space ball of rage, tiny, filled to the top with anger, sometimes a vampire