The discovery of 13 diffuse interstellar bands with the longest wavelengths detected to date could be the key to solving a 90-year-old mystery. In addition, the finding supports recent hypotheses about the presence of large, possibly organic, molecules hidden in interstellar dust clouds.
For 90 years, diffuse interstellar bands have been detected by analyzing starlight. It does not matter which way a telescope is pointed; they are detected in light from virtually any part of the universe. Its existence reveals that light passes through clouds of gas and dust with a rather complex chemical composition.
Diffuse interstellar bands have been a puzzle since their discovery 90 years ago. The 500 bands identified before the new study are mostly in visible light and near-infrared wavelengths (the infrared segment closest to visible light in the spectrum). The observed lines do not match the lines predicted for simple molecules, and cannot be attributed to a single carrier.
Low-energy absorption lines discovered by the team of Paco Najarro, from the Department of Astrophysics at the Astrobiology Center in Madrid, Spain, Donald Figer, director of the Detector Center at the Rochester Institute of Technology, United States, and Thomas Geballe of the Gemini Observatory (made up of telescopes in Chile and Hawaii), tighten the fence around the nature of diffuse interstellar bands, allowing to rule out some of the possibilities about their origin. From now on, future theoretical models on the wavelengths absorbed by these mysterious particles will have to accommodate these lower energies.
Observations in different galactic directions indicate that the material responsible for these diffuse interstellar bands “survives” under very different physical conditions of temperature and density.
Life’s “seeds” rained on the planet
According to the most recent hypotheses on diffuse interstellar bands, they indicate the abundance of organic molecules in interstellar space. Perhaps, as Figer reasons, they are chains of amino acids. This, added to other indications, supports the theory that the chemical seeds of life originated in space and then “rained” on the planets.