In the study, the
BUBBLY method has been applied to the "Antennae", in which the interaction between the galaxies is causing a major burst of star formation, leading to many star clusters, each surrounded by a bubble of expanding gas. The researchers have been able to calculate how much energy is being fed into the interstellar medium from each individual bubble, and from the sum total of all the bubbles, including a decent estimate for those which are too small to be fully detected.
"The importance of the bubbles", says Artemi Camps-Fariña, the lead author on both of the articles, "is that they let us measure the effects of feedback caused by massive star clusters on the rest of the galaxy in which they lie. This is being recognised as very important. Theorists who aim to model how galaxies are formed and evolve had a major problem when they made models without feedback. In those models star formation was far too rapid, so that all the available gas would have been used up when the universe had reached no more than one tenth of its present age. All galaxies would now be passive without any current star formation. But the feedback process, in which massive star clusters blow large bubbles, slows down the star formation rate, as it stops new gas from condensing so quickly into stars. It reduces the overall star formation rate by a big factor and has let galaxies such as the Milky Way produce their stellar populations in a much more extended time frame".
"Although this general idea is not new", says John Beckman, one of the authors of both articles, "our ability to measure the properties of the bubbles is giving us a way to quantify the effect and to match basic theory with the observed properties of galaxies".
More information:
Artemi Camps-Fariña, et al., 2017, "Physical properties of superbubbles in the Antennae galaxies",
MNRAS, 468, 4134 [ ADS ].
Artemi Camps-Fariña, et al., 2015, "BUBBLY: a method for detecting and characterizing interstellar bubbles using Fabry-Perot spectroscopy", MNRAS, 447, 3840 [ ADS ].
"Superbubbles in the interstellar medium", IAC Press Release, 1st May 2017.
GHaFaS: Galaxy H-alpha Fabry-Perot System for the WHT, web site.