Saturday, September 1, 2012

Neutron Stars- Formation, Mass and Size, Pulsars, Energy Output, Gravity and Temperature

Note: It would be highly beneficial if you had my other "Large Numbers" article open while you read this, since the numbers in this article are mind-numbingly large. (see the difference between a million and an undecillion, for example!)
A neutron star. This picture is from , Neutron stars are 4-8x the mass of our Sun, or even better, the mass ranges from 1,320,000 to 2,640,000 Earths

Mass and Size Comparisons: Neutron stars are actually a new step in the life of a star, almost as if a star could enter metamorphosis. When a normal albeit large star (high mass) of about a minimum of 4-8 solar masses and a maximum of 20-30x our Sun's mass collapses, they goes supernova and a very special process sometimes occurs (written below), which simply causes the dying star to become a new kind of star, one being about 1.35-2 solar masses yet is only 39 to 58 miles in circumference, with 46 miles as the average. The Sun then, has a radius 60,000x that of a neutron star, yet the neutron star has up to double the mass! The gravity must truly be unbelievable. Read on!
Math Example, you can skip this if you want:
So a neutron star with a radius of 10 km and would have a 39 mile circumference after km to miles conversion. Remember that C = 2pr which is (rounded)
2×10×3.14 = 62.8km×0.621371192 miles = 39.04 miles circumference.
The "mi" equals how many kilometers equal in miles, which you multiply for sake of km to miles conversion only.
Mass and Size Comparisons Continued: So picture our Sun being 35% to double its mass, and now picture it being compressed from 2,713,406 miles in circumference to 46 miles, or less, as some neutron stars are even smaller but remain just as dense or even denser. The sizes of neutron stars are limited by laws of relativity, however, but that's awful technical to get into. Anyway, it's like taking the Earth and mushing it into the palm of your hand and while you mush it, it just gets denser rather than losing density (lose compactness) even though it is shrinking in size. So with that in mind, I'm sure you can imagine the gravity involved in this type of star. Or better, imagine the Sun being double its size but smaller than a small town (oh semantics, you old dog!)
This is why mass and size are deceiving in astronomy! But it still gets more amazing than this. Our Sun is about 4.386 nonillion lbs. (4.386×1030) and a neutron star is about 6.14 nonillion lbs (6.139 x 1030) so the weight of the neutron is about 71% "heavier", so to speak, so at least the mass and weight seems to make sense, even if the size seems wrong. On the flip side, however, another way to word it makes is seem unrealistic, since the neutron star is still only 46 miles all around yet weighs 71% more, so to speak again. It's hard to grasp something with that much mass being so small, since on Earth bigger is always heavier. Can you imagine a small man 5ft tall weighing 700lbs but not look fat? I sure can't.
Formation- Simpler Explanation: Now as I said up above, a neutron star is born from a star a minimum of 4-8x the mass of the Sun. As simplistically as it can be written, this large star will supernova (like all stars do) and then re-form into a neutron star. During the supernova the neutrons stay in the dead center due to massive heat and density, which holds them together in a tight ball while the rest of the star is blasted apart in a mighty shock wave. These neutrons (uncharged iron particles) inadvertently form into a new star core that is 1.35-2x denser than the star it was prior to the supernova, and the sheer gravity of this ultra-condensed core of neutrons pulls some of the star matter that blasted away back inward, called an implosion (inward explosion), and thus the star re-forms into either a neutron star whose core is now made entirely of super-condensed neutrons or into a black hole, perhaps the most destructive force in the universe.
Formation- Technical Explanation (it's not so bad!): In a large star the core continues to "fuse" (nuclear fusion) heavier and heavier elementary particles like oxygen, carbon, nitrogen, neon, silicon, titanium and finally iron. Iron actually requires energy to fuse, so an iron core builds up since there is not enough energy to fuse all of the iron, leaving most of iron untouched. The core then cools off since the iron requires so much energy just to fuse (burn, so to speak.) The collection of iron causes electron degeneracy pressure that had been supporting it against its own gravity to collapse and the star explodes inwardly, called an implosion. This implosion crushes the core to about twice the density of an atomic nucleus (the center of an atom). The core then stiffens and rebounds, sending out a shock wave into the outer layers of the star. The shock wave quickly stalls like a car on a hill and then begins falling back toward the core from the gravity. The core begins ringing like a bell transferring violent acoustic energy into the shock wave and restarting the blast all over again. This last shock wave finally blows the star apart leaving a neutron star or black hole. The iron particles that originally required too much energy to fuse become completely uncharged, called neutrons, and form the super-dense core of this newborn star.
Food for Thought: What's cool too is that a supernova like this has so much force that the outer star matter can fly out into space at around 71,000,000 mph! That's 10% the speed of light! Only large amount of antimatter could explode larger and faster than this, but thankfully it's unbelievably ridiculously hard to harvest (explained in my "Variables in Space Traveling" article, and read my article called "Supernovae" if you want to know more about these stellar explosions. Another tidbit of neat facts is that it's widely believed some of the larger neutron stars become black holes when they die. In fact, similar to a black hole, a neutron star's matter is so dense that a lump of that matter the "size" of a sugar cube could weigh as much as all of humanity, and that these stars have magnetic fields millions or even trillion times that of Earth's. I have also heard that a teaspoonful of neutron star matter weighs billions of pounds, but I don't know how astronomers can know this! One last tidbit about the formation of neutron stars is that they typically are binary in nature, meaning they have a companion object more often than not, and they orbit each other, stripping each other of matter in violent trade offs of matter and force, usually resulting in the more massive neutron star becoming even more massive. There is a real NASA movie below showing this process.
Pulsars: Simply put, these are neutron stars that seem to pulse because they are spinning, where particles around the star spin around and appear to blink/pulse to us. Pulsars have particles that jet outward and are moving almost at the speed of light above the magnetic poles of the neutron star. These jets are what produce the mega-intense beams of light which look like pulses to us.
The Tsar Bomba had a mushroom cloud that was seen from
620 mi away. The tip-top of the cloud is 45 miles
and the base is 25 mi
Below is a comparison of energy outputs for an average neutron star. There are joules outputs since most people know what that measurement is (1watt of 'power' measures total 'energy' in joules per second for something), and then equivalences in megatons and the power of Earth's best bombs. However, since people know the power of the atom bomb, I will say this--- the atom bomb had a yield of a teeny tiny 21,000 tons of TNT (21 kt) and was able to destroy the entire city of Hiroshima, but bombs today are measured in megatons (Tsar Bomb =2380.95 atom bombs), making the atom bomb seem truly microscopic in energy output by comparison. The atom bomb is only 0.00042 (4.2×10-4) the yield of the Tsar bomb. It is so minuscule that I assume most people would not be able to grasp the size of these numbers when multiplied by 45 digit numbers.
Note: The Tsar Bomba, whose blast was many orders of magnitude smaller than the energy of neutron stars, was still seen almost 620 miles away from ground zero. The subsequent mushroom cloud of the Tsar Bomb was about 45 miles high (nearly eight times the height of Mount Everest), which meant that the cloud was well inside the mesosphere when it peaked. The base of the cloud was 25 miles wide. These numbers are only two to three digits (50 mt), let alone numbers with 29-46 digits representing force also in megatons also.
An average "power" Neutron Star energy output per second----
Neutron Star Output in Joules: 52.3 quathordecillion or 5.23×1046/ or 52,300,000,000,000,000,000,000,000,000,000,000,000,000,000,000
Supernova of a Star: Between 1 to 2×1044J or 1 to 2×1044 or 100-200 tredecillion or 100-200,000,000,000,000,000,000,000,000,000,000,000,000,000,000
Value In Megatons: 13.7 sextillion or 1.37×1031 or 13,700,000,000,000,000,000,000,000,000,000
Atom bomb=0.00042 megatons (listed this as a joke, it's not even 1 mt, haha)
Equivalence in 50 megaton Russian Tsar Bombs: 274 octillion or ~2.74 x 1029 / or 274,000,000,000,000,000,000,000,000,000 Tsar bombs, which is the most powerful bomb ever made
Equivalence in Little Boy Bombs: 833 nonillion/8.33 x 1032 or 833,000,000,000,000,000,000,000,000,000,000
Equivalence in Gallons of Gasoline: 396 undecillion or 3.96 x 1038 or 36,900,000,000,000,000,000,000,000,000,000,000,000,000
A neutron star puts out only slightly less destructive energy than a supernova. To illustrate this power, since numbers fail to encapsulate this power, watch the real footage from NASA.GOV!
The movie shows all too well the super-colossal power of a neutron star. It's accretion disk briefly unbalanced when its massive gravity pulled in a cloud of high-energy gas into itself, causing a mega-gargantuan explosion with the power of thousands of billions of trillions of atoms bombs. This explosion disrupted the star's fusion processes, but the star recovered its balance and lives on!
10 second movie-- "CITA and NASA have captured unprecedented details of the swirling flow of gas hovering just a few miles from the surface of a neutron star, itself a sphere only about ten miles (16 km) across...[and] pouring out more energy in three hours than the Sun does in 100 years...[NASA and CITA could] see details as fine as the neutron star's accretion disk, a ring of gas swirling around and flowing onto the neutron star, as the disk buckled from the explosion and then slowly recovered its original form after approximately 1,000 seconds...All of this was occurring 25,000 light years from Earth, captured second-by-second in movie-like fashion through a process called spectroscopy with NASA's Rossi X-ray Timing Explorer."
This is a neutron star that spins, called a pulsar. It's gas jets spin at nearly the speed of light (almost 186,282 miles per second). The jets of gas spin fast and appear to "pulse" from Earth's perspective.

Mass by comparison, scientific notation----
Neutron star: about 5.92×1030 lbs to 8.77 x 1030 lbs
Sun: about 4.39×1030 lbs
Earth: about 1.32×1025 lbs
Mass by comparison, showing all of the zeroes----
Neutron star: 5,920,040,052,146,700,000,000,000,000,000 to 8,770,429,706,884,000,000,000,000,000,000
Sun: 4,385,214,853,442,000,000,000,000,000,000
Earth: 13,169,533,682,832,000,000,000,000 lbs
Gravity by comparison (acceleration of objects toward mass, e.g.: free falling speed, rounded up)
Neutron star: 7×1012 m/s2 or 7,000,000,000,000 m/s2 or 22,965,879,300,000 ft/s2
Earth: 9.80665 m/s2 or 32.1741 ft/s2 (so so so tiny! Doesn't even need scientific notation!)
Circumference (length measured around entire sphere)----
Neutron star: 39 to 58 miles
Earth (at equator): 24,859.82 miles
Sun: 2,713,406 miles
Temperature, (astronomers do not have enough data for accurate temperatures yet)----
Neutron star: 1.799 x 109 or 1.8 billion or 1,799,999,540.6 ºF (highly speculative)
Sun: 15.7 x 106 or 15.7 million or 15,700,000°F outer temp, 9,940°F photosphere, and a speculated 27,000,000°F (million) core
Earth: averages 57.2°F to 59°F for planet
record highest of 159°F in the Lut Desert in Iran recorded by a NASA satellite
record low of -129°F in Antarctica measured by the Russian Vostok Station
The coming probe aptly called the Solar Probe Plus is set for launch to our Sun in 2018, and is hoped it will bring back far more accurate numbers about our Sun's mass, temperature, overall size and the whole sha-bang. The information we have now on our Sun is basically what astronomers use in their comparative studies of other stars and cosmic objects. When we learn more about our Sun, other stars should be much easier to understand. Sometimes answers just lead to new questions though!
Now you're a neutron star pro. I hope you enjoyed this article, since it was by far the hardest I have written so far! Neutron stars are still a puzzle to most astronomers, but hopefully these facts and figures from credible astronomers and NASA will not change too drastically in the coming years of discovery and exploration!


  1. I was looking up "what is the energy output of a neutron star?" And happened to stumble across this blog post of yours. It was incredibly detailed and I appreciate that, I want to know your sources on the energy output of a neutron star?

    So far the NASA link you provided only describes the energy output of the much rarer "superburst" given off by its fusion of carbon atoms built up over years with their more common helium bursts.

    1. I can't remember, I wrote this 6 years ago. I'm not even sure with this amount of time if this data is even considered correct anymore friend