Tracking molecules in the interstellar medium

The stars are not formed from nothing, but the follow -up of gas and dust that ends up forming stars is difficult. They float around the galaxy at almost absolute zero, essentially emitting no light, and generally makes life difficult to astronomers. But part of the way they make life difficult is in fact the key to studying them – they have absorption lines that detail the type of material that light passes on its way to the earth.

A new newspaper published on the arxiv The preparatory server by Harvey Liszt of the National Observatory of American Radio-Astronomy and Maryvonne Gérin de la Sorbonne details how the monitoring of these absorption lines via astronomy radio can draw the “dark neutral environment” of interstellar gas throughout the galaxy.

The article describes the results of 88 lines of view, which in this context is a straight line of the earth to a very brilliant object, such as a quasar or another galaxy. While the light of these brilliant objects goes towards the earth, part of the light is absorbed by the interstellar medium (ISM), creating a distinct dark spot in the spectra from the light source.

These absorption lines are particularly strong in the radio spectrum, so the article focused on the data of two different radio antennas. The ATACAMA GRANDIMETER / SUBMILLIMETER (ALMA), one of the best known radio stakes in the world, the Millimetric Radioastrome Institute at the Sorbonne, and the Arizona Radio Observatory, all contributed the data to this document, with some of the data collected 30 years ago.

Six different ions were at the center of this article, with different levels of success. Formyle Cation (HCO⁺) was the most commonly found molecule, being present in 72 of the 86 lines of view for which he had collected data. It seemed to be the best predictor of the place where molecular hydrogen, the most abundant molecule in the universe, but which is really difficult to detect directly. It is formed when h₂ And some other elements are affected by cosmic rays, so a large amount of HCO⁺ would also be indicative that a large amount of H₂ would reside in the same area.

Hydrogen cyanide (HCN) was another key study molecule. Astronomers previously thought that this molecule was only present in large quantities in dense clouds of gas where the stars were actively formed. However, the article shows that it is present throughout the ISM, forcing additional refinement of the process of forming this molecule.

The radical of ethynyl (c₂H) was another key component of the study. It is the second most abundant after HCO⁺And, as a very simple hydrocarbon, can show how complex hydrocarbons can be transformed when they undergo reactions in the ISM. The study also notes that the report of C₂H to HCO⁺ Changes based on the location conditions of this area of space, such as the dust content, the calculation of this ratio for different areas could undo (figurative) a light on other processes that occur there.

Other molecules were more difficult to follow. The study found no carbon monosulfure (CS). Carbon monoxide (CO) was only found on lines of view with HCO⁺making him redundant, even if he was about 100 times brighter than HCO emissions⁺.

Regular formalous radicals (HCO) are also omnipresent throughout the galaxy, but, depending on the article, their absorption lines are much more difficult to detect, which makes them less useful to estimate the presence of these dark gas clouds. Hco⁺ Has much more clearly defined lines, which facilitates use for this purpose.

It turns out that tracing all these gases throughout the galaxy is an effective way to find the potential areas of stars formation, and to look at the ISM itself begins to come together at the start of this process. While more powerful telescopes are online and we are able to increase the signal / noise ratio of some of the signals of these molecules, they will end up presenting a clearer image of this “dark” part of the universe which is full of the next series of star stuff.