There’s more to the Milky Way than meets the eye. And we are lucky enough to have exceptional instruments and scientists to make the invisible visible. One such phenomenon is the dark clouds that stretch through our galaxy, and now researchers have produced the most detailed map of them yet.
To see these large dark reservoirs of gas, the researchers used the Nobeyama 45-meter (148-foot) radio telescope, located in Nagano Prefecture in Japan. The telescope can detect carbon monoxide in the clouds and astronomers can use this as a proxy to study them.
The observational project, whose results are published in the Publications of the Astronomical Society of Japan, led to the discovery of giant molecular filaments that nobody had been able to resolve in detail before. By studying the carbon monoxide, the team was able to track the gas movements and estimate quantities like temperature and density.
The radio telescope was capable of tracking different types of carbon monoxide. Two had different isotopes of carbon (Carbon-12 and Carbon-13) and one had a different isotope of oxygen (Oxygen-18). While isotopes have the same chemical properties, they differ in their physical properties as they have different numbers of neutrons in their nuclei, which affects how heavy or light they are. And astronomers can see these differences.
The map covers an area equivalent to 520 full moons and is three times more detailed than any previous radio map of the Milky Way. The data allows us to probe connections between various aspects of our galaxy, from its large-scale interstellar medium all the way down to the core of molecular clouds where star formation takes place.
“This radio map will serve as a fundamental data set for future observational studies. We expect many discoveries by researchers around the world based on this map,” the international team said in a statement.
The observations were made possible by the installation of the FOREST instrument on the Nobeyama telescope. The astronomers conducted 1,100 hours of observations between 2014 and 2017, covering the narrow band of gas structures on the plane of the Milky Way.
The map is part of the FUGIN project (FOREST unbiased Galactic plane imaging survey with the Nobeyama 45-m telescope) and will be publicly released in June 2018. The FUGIN collaboration believes that the map will be employed by a whole range of telescopes and observatories that use a wide variety of wavelengths, not just radio.