In spiritistic or spooky folklore, a poltergeist It comes to be something like a noisy ghost and although some living acquaintance with these characteristics comes to mind right now, in general, the word refers to dead ghosts, that is, spirits, that make pans or armchairs levitate and that from the angry they even bite and pinch. Fear and suggestion have always been powerful control tools and they help a lot to increase the number of followers of some programs (electoral as well). But it’s not one of those poltergeist of which I am going to speak today, but of a Poltergeist that is place. A planet like there is no other.
It was the year 1992 when two astronomers, A. Wolszczan y DA Frail, using the 305 m telescope of Arecibo, made precise measurements of the arrival times of the signal from the pulsar PSR1257 + 12, also called Lich, which is 2,300 light-years away in the constellation Virgo. Let us remember that the Arecibo telescope was for many years the largest in the world and that we lost it in 2020. PSR1257 + 12 is such a precise beacon that by simply measuring the alteration of its period they determined that it was orbited by two planets, the first known extrasolar. One of them is Poltergeist, it has a mass four times the mass of the Earth and there a year lasts 66 days. Now we know that there is another planet, that is, there are three in the system. His star is much hotter, smaller and older than ours. The point is, we didn’t expect those planets to be there. Let’s see why.
To understand the perplexity that the Poltergeist detection produced, we have to go into the microscopic world for a moment and, again, like last week, mention the neutrons. This time simply to inform that under high-density conditions a proton (positively charged particle) and an electron (negatively charged particle like those that are continually moving through our cables, plugs and appliances) can combine to form a neutron (particle without charge). The conditions necessary for this to occur are found in the nuclei of stars when they can no longer support the structure by nuclear fusion. Of course, as long as they were born with a certain mass. In a supernova explosion, an ordinary star is transformed into one of neutrons: matter compacted to nuclear densities, very small and with so much surface gravity that to put a telescope like the one into orbit James Webb from its surface we would have to launch it at half the speed of light.
The mass of the Sun, which now occupies a sphere with a diameter of about a million kilometers, would happen in a neutron star to be contained in a sphere of a few. And I am not going to say its size in soccer fields, or in units of madriles The manhattans, So there it goes, a neutron star has the mass of the Sun concentrated in a radius with the approximate distance that separates Arriondas from Ribadesella traveling by river. Read as my little act of rebellion against the centralism that prevails, also, in the references that are used for the units of measurement.
Inside neutron stars, what are known as pulsars rotate at speeds that can reach 1,000 revolutions per second (a normal fan does it at 25) and have very strong magnetic fields. The pulsar in the Crab Nebula rotates in such a way that it is as if a lighthouse flashes 30 flashes per second. In these objects of inconceivable densities, matter has properties worthy of being mentioned in a comic when Dr. Maldad is recounting the experiment that will destroy humanity, that is, there matter flows without friction and conducts electricity without resistance. Remember that the first pulsar was discovered by Jocelyn Bell when she was a doctoral student, and here I have no choice but to say now that reality is always more than fiction as a nod to sad satire Don’t look up. They continue to pay little attention, even in movies, to doctoral students.
Anyway, let’s go back to Poltergeist, the most obvious formation scenario for these planets is that they did so with the star itself, in the same way as our solar system, but around a much more massive star, which we are not sure is possible. Suppose for a moment that this is the case, that massive stars, with more than eight times the mass of the Sun, can form a planetary system. What then has to happen for us to see them in the form of planets around a pulsar is that they survive the vicissitudes of the star’s life. And that is already a problem, since they should not only survive being swallowed by the star when it turns into a red supergiant, but also one of the most energetic events that occur in the universe: the supernova explosion. Let’s recognize that this is quite unlikely, as we like to say in science. We do not say impossible, categorical statements are left to others.
So we have to look for other options, which require planets to form later, after the supernova explosion. Hence the relevance of its name. Poltergeist would return from the dead to haunt an old star system and cause disturbances in the pulsar’s period. There are several ways for this to happen. Two of them involve the formation of a protoplanetary disk, either from part of the material that falls back towards what remains of the star after the supernova explosion, or from the remains of material evaporated from a star. companion that also the intense radiation of the pulsar can literally leave in the bones.
Planets orbiting pulsars are rare. Only a few are known. The three orbiting PSR1257 + 12 probably owe their existence to a broken star. Although they are the least likely places, perhaps we should not rule out that they are impossible places to start over. I mean life.
Eva Villaver She is a researcher at the Astrobiology Center, dependent on the Higher Council for Scientific Research and the National Institute for Aerospace Technology (CAB / CSIC-INTA).
Cosmic Void It is a section in which our knowledge about the universe is presented in a qualitative and quantitative way. It is intended to explain the importance of understanding the cosmos not only from a scientific point of view but also from a philosophical, social and economic point of view. The name “cosmic vacuum” refers to the fact that the universe is and is, for the most part, empty, with less than one atom per cubic meter, despite the fact that in our environment, paradoxically, there are quintillion atoms per meter cubic, which invites us to reflect on our existence and the presence of life in the universe. The section is made up of Pablo G. Pérez González, researcher at the Center for Astrobiology; Patricia Sánchez Blázquez, Associate Professor at the Complutense University of Madrid (UCM); Y Eva Villaver, researcher at the Center for Astrobiology.