One survey used NASA’s Chandra X-ray orbital telescope to study winds blown from the center of a galaxy close to our own. The results showed some of its effects and determined its origin: a super cluster of stars close to the galactic core.
11.4 million light-years from Earth lies the galaxy NGC 253, from where a wind composed of gas is blown into intergalactic space. It travels at temperatures of millions of degrees, with amounts of gas equivalent to about two million Earth masses a year.
Classified as a starburst galaxy (where stars form faster than normal), with stellar production three times faster than in the Milky Way, NGC 253 has young and very massive stars. They are what blow the gas wind from their surfaces, but even more powerful winds are triggered by supernovae.
Chandra data show that these winds blow in two opposite directions from the galaxy’s center, and gas densities and temperatures in the wind are highest in regions less than 800 light-years from the galaxy’s center. The farther they move away from there, the more the gas cools and disperses.
This contradicts models that describe the winds of starburst galaxies as “spherical”. On the other hand, the observed density of the gas in the winds is in agreement with more recent studies, in which it is suggested that a concentrated wind must be formed by a ring of “superclusters of stars” close to the galactic center.
This may be the case for galaxy NGC 253, but on the other hand, some details are missing for the observations to fit recent models. For example, if the wind cools rapidly as it moves away from the center of the galaxy, perhaps the wind is blowing cooler gas. Figuring out how and why this occurs can be helpful in fitting theory with observation.
Another detail is that this wind is composed of elements like oxygen, neon, magnesium, silicon, sulfur and iron, things that become much more diluted the farther they get from the center of the galaxy. This effect was not seen in another starburst galaxy, M82. More studies will be needed to answer these questions.
The research was published in The Astrophysical Journal.
Source: The Astrophysical Journal, NASA
