An article submitted for publication in “The Astrophysical Journal” reports a study of the exceptional rate of star formation in the M82 galaxy. A team of researchers led by Alberto Bolatto of the University of Maryland, College Park, used the James Webb Space Telescope to map powerful galactic winds that expel vast amounts of gas caused by star formation and supernova explosions.
The NIRCam instrument is the one used in particular to trace the origin of that activity back to dense star clusters in the galactic disk. This new study of M82 offers advances in understanding star formation and how this activity is affecting the galaxy.
The study of star formation processes remains a very important subject of research in the field of astronomy. The processes that lead to the birth of stars are literally shrouded in a blanket of mystery given that they occur in a cocoon of gas and dust. Many electromagnetic frequencies are blocked, so seeing inside the molecular clouds in which stars are born is difficult. Infrared is among the bands of frequencies that pass through those clouds, and the James Webb Space Telescope is the most advanced instrument in existence when it comes to seeing in infrared.
The M82 galaxy has been studied in the past with other space telescopes such as Hubble and Spitzer, and now Webb offered many new details. The top image (NASA, ESA, CSA, STScI, A. Bolatto (UMD)) shows the M82 galaxy in Hubble’s view on the left and the area of very intense star formation seen by Webb on the right.
The researchers exploited the presence of molecules of the polycyclic aromatic hydrocarbon type to use their movements generated by the winds within the M82 galaxy. The connection between these molecules and galactic winds was surprising given that it was unknown. Radiation from nearby stars and protostars is supposed to destroy polycyclic aromatic hydrocarbons yet they are present in abundance. Perhaps they are replaced by other molecules generated in colder areas, and this could be another topic for study.
The connection between polycyclic aromatic hydrocarbons and galactic winds was exploited to map their motion generated by star formation and by supernovae produced by massive stars that are at the end of their lives instead. NIRCam allowed to obtain many details on the origin of winds in star clusters and their impact on the surrounding environment.
This study represents only one phase of monitoring star formation in the M82 galaxy. The team led by Alberto Bolatto will conduct the next phase using spectroscopic observations of M82 as well as other images obtained with the James Webb Space Telescope. That data will allow to accurately calculate the age of star clusters, which is crucial to understand the duration of the various phases of star formation.
The M82 galaxy is nearby, “only” 12 million light-years from Earth. However, the very high rate of star formation is similar to that observed in primordial galaxies that are a thousand times further away. This means that the study of M82 can also provide useful clues to reconstruct the early stages of the history of the universe.
