A Black Widow spider, and the Australian Redback spider, are known for eating their mates.  Now astronomers have discovered cosmic black widows, pulsars that devour their mates.

What happens in a binary star system when one star is a normal low-mass star and the other forms into a neutron star?  The neutron star becomes a pulsar and eventually destroys the normal star.  Scientists have named these pulsars after the spiders, black widows and redbacks.  So far, they have found 18 black widows, which are smaller and of much lower mass than a redback pulsar of which they have found 9 so far.

When a star explodes as a supernova, it forms a neutron star which has more mass than our sun but is smaller than a city.  The neutron star begins to rotate at about thirty times a second sending off radio, light, X-rays and Gamma-rays.  As the star rotates, it appears from Earth that the energy is pulsing, thus we call it a pulsar.  Eventually, the pulsar will slow and fade away.

Scientists then discovered pulsars that were spinning much faster, up to 43,000 times a minute.  These were called millisecond pulsars.  More than half of them were part of a binary star system.  But scientists never knew why some pulsars spun so fast.  Now, the Fermi Gamma-ray space telescope is shedding light on the situation.  It appears the neutron star is devouring its mate, and the energy in that process makes it spin faster and faster.

Studying the pulsar PSR J1311-3430, it was noted that one side of the normal star appeared blue and the other red.  In astronomy, blue is hot and red cool.  So the star had a hot side at near 21,000 degrees F and a cool side at 5,000 degrees F.  The pulsar was heating one side of its companion star while the far side remained cooler.  The pulsar was heating the companion star to a point where it was ionizing it.  Eventually, over millions or billions of years, the companion star will be completely eradicated.  As the ionization blocked a lot of the radio waves, Gamma-rays were not blocked, thus Fermi was able to measure the effects of the pulsar on the star.

It is suggested that the millisecond pulsars found without mates have already destroyed the companion.

The artist's concept below shows PSR J1311-3430 with its beams of radio (green) and Gamma-ray (red) heating one side of its companion star that it will eventually evaporate.

When a star reaches the end of its life, its Hydrogen used up, large stars explode in what we call a supernova.  But why?  And how?  It has been one of the biggest mysteries in astronomy.  But now, NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) is unlocking the answers.

NuSTAR is a high-energy X-ray observatory and has been studying Cas A, a supernova remnant in the constellation Cassiopeia.  The light from the explosion reached Earth only a few hundred years ago, so now we can see the stellar remnant from not long after the explosion itself.

When a massive star explodes as a supernova, light elements are fused together producing heavy elements such as gold and iron.  NuSTAR is the first telescope that can map the radioactive elements in a supernova remnant.  NuSTAR has mapped titanium-44 in Cas A.

Computer simulations have always shown that the shock wave created when a massive star collapses will stall out and the star will not explode.  But the star does in fact explode, so scientist have been left with a great mystery.  By looking at the titanium-44, NuSTAR has shown that the element has an unstable nucleus and is produced at the heart of the star.  The star is literally sloshed around inside.  This causes the stalled shock wave to re-energize and finally cause the star to explode.

Other models of a supernova suggest the star starts rotating rapidly and shoots jets of narrow streams of gas that cause the explosion.  But the NuSTAR data contradicts this theory.  NuSTAR found no titanium in the radioactive remnant in narrow regions matching the jets, thus the jets did not trigger the explosion.

A large cloud of carbon monoxide gas has been found around the star Beta Pictoris.  The discovery was made by the Atacama Millimeter/submillimeter Array (ALMA) in Chile.  Beta Pictoris is in the southern hemisphere constellation of Pictor.

What makes this cloud such a mystery is that carbon monoxide is usually destroyed by starlight.  So something is making the cloud replenish itself.  Carbon monoxide is given off when icy objects such as comets collide.  This could explain the cloud.  But for the cloud to be as large as it is, there would have to be a vast number of comets colliding at a rate of a collision very five minutes. To concentrate that many comets in only place would require a gravity source from a planet about the size of Saturn.  A planet that size has not yet been detected but certainly could exist.

Another possibility is that the cloud was created in a collision of two icy objects each the size of Mars.

The gas is concentrated in a single clump about 13 billion kilometers from Beta Pictoris.  This is about three times the distance from our sun to Neptune.  Why the gas is so far away from the star is another mystery.

Beta Pictoris is a young, just forming solar system.  It has one known planet in an orbit of 1.2 billion kilometers from it.  The star is surrounded by a disk of dusty debris.  Comet bombardment would be common at this time in its history and carbon monoxide indicates that it could someday become a good habitat for life.  Comets contain carbon monoxide, carbon dioxide, ammonia and methane, but the major component of comets is a mix of dust and water ice.