Structure of a massive dust clump reveals the growth mechanism of giant stars

(ORDO NEWS) — Using the Atacama Large Millimeter Array (ALMA) radio observatory, Argentine astronomers studied a massive molecular clot known as AGAL35 (or AGAL G035.1330-00.7450). The results will help to gain a deeper understanding of the formation of massive stars.

Observations show that high-mass stars form as a result of the fragmentation of massive molecular clumps. Such clumps can collapse under the influence of their own gravity and fragment to form multiple nuclei. However, scientists still cannot come to a consensus regarding the mechanism of formation of massive stars: whether it occurs as a result of the collapse of one monolithic nucleus or as a result of a global hierarchical collapse of a molecular clot.

The molecular clot AGAL35, located at a distance of about 6850 light-years from Earth, shows signs of limited fragmentation, and therefore was chosen by scientists as a good “laboratory” for studying the early formation processes of massive stars.

Therefore, a team of astronomers led by Martin E. Ortega from the University of Buenos Aires, Argentina, using the ALMA observatory, studied the fragmentation and kinematics of molecular gas in the AGAL35 clump to clarify its internal structure.

As a result, it was possible to confirm four dim in the infrared range of dust cores with masses less than three solar masses, that is, less massive than previously assumed. In addition, a number of other properties of these nuclei have been studied, including their temperature and possible chemical composition.

Given that these four nuclei have relatively low masses, the authors conclude that the only possibility for the formation of massive stars in molecular clumps such as AGAL35 is the competitive accretion mechanism.

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