Forbidden Line

2021-05-25   |   by CusiGO

Prohibition may be a good title for a black novel. A mysterious passage, who read it dead. It’s a survey of sloppy, maybe smart people who try to clarify these strange events. If we adjust the plot a little bit and accept that the Sherlock are natural death astronomers, we have our “name of the rose” conspiracy story, which is a mechanism discovered nearly 100 years ago to explain the luminescence of many celestial bodies. The last detail is that the only corpse is a star, forbidden line written in a book on the astrophysical equivalent: a ghost.

In 1868, Sir William Huggins, a British astronomer, gave the astronomer a name: when the light from some nebulae decomposes in the spectrum, bright green emission lines can be seen. Since the light was not observed in the gas spectrum of the earth’s laboratory, the British Sir suggested that it was a new chemical element. He didn’t eat too much head, which he called fog. Let’s remember that in the absence of a theory, the only way to determine the properties of the substances responsible for light that we see in the sky is to compare their lines with the spectra produced in the laboratory. It was not discovered by the IRA until 1927. They are just ordinary elements, such as charged oxygen and nitrogen, or ionized elements, responsible for producing this light on some astronomical objects, Bowen said.

Although these lines are observed on many objects with very different energy sources, such as supernovae, planetary nebulae, black hole environments in galactic active nuclei or aurora borealis, they are what we call forbidden lines. The term is misleading if we call them “unlikely launch lines on the ground” (let’s see what we see, anthropocentrism always slips away in one way or another), Although we have to admit that this is one of the few times that astronomers use hooks to name something.

Interestingly, we’re going into a tiny world, a quantum world, to understand how light is produced, which is very useful for understanding the universe. For example, it enables us to measure how much a galaxy billions of light-years away from the earth gets from the oxygen we breathe. We now know that in order to emit this light, we basically need two things: a light source with high energy and a gas with extremely low density. Suppose we have these two components, let’s turn it into something much smaller than the ant man and see what happens at the elementary particle level.

All atoms have a dense nucleus with a positive charge, protons are there, and we have electrons in their clouds around this small structure. Electromagnetic force, one of the four basic interactions in nature, combines the two as long as no photon can provide so much energy to an electron to separate it from the atom. We already know why we need energy: extracting electrons from proton control. This process, called ionization, takes place in the ionosphere of the earth’s atmosphere.

Now let’s imagine that these ionized atoms are like skyscrapers with a series of floors where the rest of the electrons live. Well, contrary to common sense, these electrons don’t like to see and live in high-rise plants, but prefer to be close to the core, in the basement. Photons act like elevators, energizing electrons, lifting them to the top of the atomic edifice, or throwing them out like Willie Wonka’s crystal elevator. Most of these towers are hydrogen’s most common atomic tower, in which only one electron rises (is absorbed) into the photon and is placed on a higher floor. The problem is, in less than a billionth of a second, he decided he didn’t want to go there, and he pulled the elevator back downstairs. The key is that some ions, such as oxygen, sulfur and nitrogen, will have a certain energy level or atomic level when they arrive without lift (no photons). In this case, it’s other free electrons (loose tearing electrons) that release energy and transport electrons trapped in the atoms to higher floors. At this level, we call it prohibition. At these atomic levels, electrons like to stay for a few minutes (millions of times longer than they are allowed). Sadly, they stay there because they can’t go anywhere else.

The elevator I just mentioned is quantum mechanics, which requires a lot of equations (and years of research) to formalize. In this technical language, we can say that when the metastable energy level of the ionized atom with low transition probability undergoes a downward transition, the emission is produced by the collisional excitation line. But back on earth, in our environment, the density of particles is always so high that collisions between atoms take energy away before they go down. That’s why the broadcast can’t be played in the lab.

Under the condition of low density of gas, we call it HII region, planetary nebula and supernova vestige. It is atomic ions such as oxygen, sulfur and nitrogen that emit these unusual lines. Forbidden beauty not only reveals the structure of the most fascinating objects in the sky, but they are so bright that we can observe them from a distance and reconstruct, for example, the chemical history of distant galaxies.

EVA villaver is a researcher at the center for Astrobiology of the advanced scientific research council and the National Institute of Aerospace Technology (CAB / csic-inta).

The cosmic vacuum is a part of our understanding of the universe in a qualitative and quantitative way. Its purpose is to explain the importance of understanding the universe, 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 mostly vacuum, with less than one atom per cubic meter, although in our environment, paradoxically, there are more than 500 million atoms per cubic meter, This leads to the reflection on our existence and the existence of life in the universe. The family is composed of Pablo G. P é rez Gonz á lez, researcher, Center for Astrobiology; Patricia s á nchez BL á zquez, Professor, complutens University (UCM), Madrid; And EVA villaver, a researcher at the center for astrobiology.

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