The NASA/ESA Hubble Space Telescope has captured an image of a bright spiral galaxy known as MCG-01-24-014, located about 275 million light-years away and emitting ‘forbidden’ light.

MCG-01-24-014 is not only a well-defined spiral galaxy, but also has an extremely energetic core known as the active galactic nucleus (AGN) and is categorized as a galaxy. Seyfert type 2.

Seyfert galaxies, along with quasars, host one of the most common subclasses of AGN.

Although the precise classification of AGNs is nuanced, Seyfert galaxies are usually relatively close and their central AGN does not eclipse their host, while quasars are very distant AGNs with incredible brightness that exceeds their host galaxies, NASA reports.

There are other subclasses of both Seyfert galaxies and quasars.

In the case of Seyfert galaxies, the predominant subcategories are Type 1 and Type 2.

Astronomers distinguish them by their spectrum, the pattern created when light is broken down into its component wavelengths. The spectral lines emitted by Seyfert type 2 galaxies are associated with specific ‘forbidden’ emission lines.

To understand why light emitted from a galaxy might be forbidden, it’s helpful to understand why spectra exist in the first place. Spectra look this way because certain atoms and molecules absorb and emit light at very specific wavelengths.

The reason for this is quantum physics: Electrons (the tiny particles that orbit the nuclei of atoms and molecules) can only exist at very specific energies, and therefore electrons can only lose or gain very specific amounts of energy. These very specific amounts of energy correspond to the wavelengths of light that is absorbed or emitted.

According to certain rules of quantum physics, forbidden emission lines should not exist. But quantum physics is complex, and some of the rules used to predict it were formulated under laboratory conditions here on Earth. According to those rules, this broadcast is “prohibited”; It is so unlikely that it is not taken into account.

But in space, amid an incredibly energetic galactic core, these assumptions no longer hold and the ‘forbidden’ light has the opportunity to shine towards us. (JO)