a mysterious explosion
Set to look for strange explosions, none like the one in 1843. That year one of the most massive stars known, Eta Carinae, exploded. It is 7,500 light-years from us, has a mass of 100 suns, and is 4 million times brighter than our beloved little yellow star. At the time of the explosion, it spewed out enough material to form several suns at a speed of more than three million kilometers per hour. But the most surprising and mysterious thing is that the star remained as if nothing had happened . A century and a half later, the Hubble Space Telescope photographed the surrounding Homunculus Nebula : two immense warts on the skin of this blue supergiant. In 1997 it was discovered that the changes in its spectrum followed a regular pattern, with a period of 5 and a half years. Is it proof that there is “something” orbiting there?
the star eater
Cannibalism also exists in-universe . Not only are there galaxies that eat others, and ours has been digesting a smaller one on the other side of where we are for millions of years, but also the stars. That happens to the poor star that accompanies a black hole that travels at high speed through the Galaxy, at 145 km/s with respect to us. The object is called XTE J1118+480 and was discovered by the Rossi X-ray satellite in March 2000 and is located just above us – with respect to the galactic plane – and very close, only 6,000 light-years away.
It is possible that this black hole was “expelled” 7,000 million years ago from one of the many globular clusters that form a spherical halo around the Galaxy and that are supposed to have been formed with stars from the first times of formation of the galaxy. Milky Way . With a mass of about seven times that of the Sun, before beginning its journey the cunning black hole picked up one of the stars of the cluster, as if it were a snack for the road . But that stellar bag of chips is nearing its end : only the inner layers are left. Now astronomers are wondering where there are more of these ‘cannibals’, estimated to number in the hundreds of thousands.
a riotous shine
If on a clear summer night we look towards the constellation of the Swan, the northern cross, in a corner we will discover P Cygni, a weak star, of fifth magnitude -with the naked eye and with a good sky we can see up to the sixth- that for the amateur astronomers is one more among the different variable stars that can be seen in the sky – although it is true that it defines a characteristic type of variables that bear its name. How wrong we are! P Cygni is one of the most luminous stars known and emits energy 700,000 times faster than our Sun. Its brightness usually fluctuates by 20% ―0.2 magnitudes― but from time to time it goes out of control. Around the year 1600 its brightness increased to the third magnitude, something that was repeated in the middle of the 17th century.
Located 6,000 light-years from us, this blue star ejects gaseous matter during its brightness changes. What we are looking at is a short stage in the life of a very massive star, lasting about 100,000 years.
The monster
Inside the supernova remnant known as W50 is a real monster, SS433. Located in theeagle constellationthrough the telescopeperceived as a faint 14th magnitude star―hardly visible with an almost professional amateur telescope, with a 30 cm diameter objective―.Located 18,000 light-years from us, would have been one of the hundreds of billions of stars that populate our galaxy if it were not for the fact that astronomers B. Stephenson and N. Sanduleak included it in their catalog with the number 433 and that they registered it as a weakly variable star. But make no mistake.SS 433 has been described as a true cosmic anomalywhich has motivated hundreds of specialized papers and has convened dozens of international symposiums.It is the engine that feeds an area full of W50 gas, very similar to the well-known Crab Nebula but with the difference that it is invisible in the optical.Astronomers have observed that the transfer of energy takes place in a way that is very common in the cosmos:two jets of matter that are fired in opposite directions and at speeds close to that of light. But the true heart of SS433 has been a real secret, to the point that some astronomer has called it the most mysterious object of the 20th century. However, recent observations with the Very Large Array (VLA) in Socorro, New Mexico ―if you remember the movie Contact is the group of radio telescopes with which the extraterrestrial signal is received―.Apparently it is a very close binary, two stars that rotate around each other with a period of 13 days.But the fascinatingis that it is a strange couple: a fairly normal star 3.2 times the mass of the Sun and a neutron star 10 kilometers wide and almost one solar mass, which “sucks” matter from its companion and forms a around it an accretion disk-like the vortex that originates when we uncover a bathtub full of water-. Due to the high speeds it reaches, much of this matter is ejected from the poles of the neutron star at 80,000 km/s, as if it were a powerful cosmic sprinkler.Is this a miniature version of the kind of process that happens with super black holes at the center of active galaxies and quasars?
Wandering star and Formula-1
100 million years ago, three gravitationally bound stars traveled through the hot center of our galaxy . It was then that something happened that changed his life forever: this triple system passed too close to the enormous black hole that occupies the center of the Milky Way, captured one of the stars and launched the other two at a speed of more than 2, 5 million kilometers per hour. This means 3 times faster than the speed that the Sun takes around the Milky Way and twice the escape velocity of the Galaxy. Along the way, the two stars merged, giving rise to a superhot blue star that, even today, outside our great cosmic city, is moving away at that heart-stopping speed.
This is what astronomers guess happened to the star known as HE 0437-5439 , one of the fastest ever detected. Since 2005 , 16 of these super-fast stars have been detected, forced exiles from our Galaxy (theory predicts that the central super black hole launches a star into intergalactic space every 100,000 years). That is believed to be the origin of the wandering stars, the ones Lee Marvin sang about in the movie Legend of the Nameless City.
