Author: Sean Cox

According to a team of astronomers who published a new study in the Astrophysical Journal, the Galaxy NGC 4490, also nicknamed “Cocoon Galaxy” for its unique shape, boasts a “dual core” structure.

One core can be visually intercepted at different wavelengths while the other can only be seen in infrared or radio wavelengths. The galaxy NGC 4490 interacts gravitationally with a smaller galaxy, NGC 4485. This “binary system” boasts approximately 20% of the size of the entire Milky Way and is located approximately 30 million light away from us.

Allen Lawrence, the study’s first author and researcher at Iowa State University, says he noticed this double core as early as seven years ago, something that had never been observed before. According to the researcher, both nuclei have more or less the same size, the same mass and the same level of brightness.

Furthermore, this double nucleus would also explain why this galactic system is surrounded by an equally unusual hydrogen plume: “The simplest interpretation of the observations is that NGC 4490 is itself an advanced melting residue.” This merger would have occurred in the past following a collision between two galaxies.

In general, double-core galaxies are very rare. Multiple supermassive black holes are thought to be at the center of these systems.

The examples of rock art from Gwion in Western Australia, discovered in 1891, may date back 10,000-12,000 years according to a team of archaeologists. The researchers used an unusual dating method: they dated the tiny grains of coal in the fossilized wasp nests created by these insects on the painted walls.

Dating rock art is always difficult since the substances that are used to paint, mostly ocher minerals, cannot be dated to radiocarbon. The researchers, therefore, thought of using the nests made by the so-called “mud wasps,” flying insects that build their nests from the mud, in this case on a rock substrate.

The researchers measured how long the grains of quartz sand that wasps from the past used to create their nests were present on the rock where the paintings were. These are nesting wasps whose nests, made of mud, petrify after abandonment. These remains can be analyzed through various complex optical techniques and it is also possible to date the traces of pollen contained in them. With this method, they established that Gwion’s rock art examples date back over 10,000 years ago.

It is a period that coincides with the end of an ice age, a period during which the level of the oceans rose and there were floods in northern Australia.

This led the Aboriginal people who lived near the coasts to take refuge inland and precisely these forced emigrations could be the object of the meaning of many drawings that often depict human figures moving with bags and headdresses.