National Astronomical Observatory of Japan



ALMA Disentangles Complex Birth of Giant Stars

| Science

A research group led by Aya Higuchi, a researcher at Ibaraki University, conducted observations of the massive-star forming region IRAS 16547-4247 with the Atacama Large Millimeter/submillimeter Array (ALMA). The observation results shows the presence of multiple, or at least two, gas outflows from a protostar, indicating the possible existence of two new-born stars in this region. Also, the radio observation results of molecular line emission of methanol revealed in vivid detail an hourglass structure created by gas outflows spreading outward while thrusting the ambient gas cloud away. It is the first time that such an hourglass structure was found in observations of methanol in high-mass star forming regions. Detailed observations of high-mass stars have been considered difficult so far because high-mass stars form in a complex environment with multiple protostars in clusters, and their forming regions are located farther away from the Earth compared to those of low-mass stars. However, high angular resolution observations with ALMA opened a new window to understand their formation environment in further details.

An artist’s concept of the distribution of the ambient gas around IRAS 16547-4247. The central high-density gas cloud is thought to contain multiple high-density protostars. Two outflows of gas spurt from the central part in the vertical and horizontal directions respectively while pushing the ambient gas away, which makes a balloon-like structure. A pair of narrow jets is the one that was found in past observations.

These observation results were published as Higuchi et al. “IRAS 16547-4247: A New Candidate of a Protocluster Unveiled with ALMA” in the astronomical journal Astrophysical Journal Letters, issued in January 2015.

This research is supported by Grant-in-Aid for Scientific Research on Innovative Areas “New Frontiers of Extrasolar Planets: Exploring Terrestrial Planets”. Guide Garay is supported by CONICYT project PFB-06.