2023-06-20 17:04:24
Dust emission maps for 39 IRDCs where massive stars are expected to form in the future – ALMA (ESO/NAOJ/NRAO), K. MORII ET AL.
MADRID, 20 Jun. (EUROPA PRESS) –
The accepted model of low-mass star formation needs to be extended to explain the formation of high-mass stars, based on data from mapping a selection of 39 interstellar clouds.
This suggests that the formation of high-mass stars is fundamentally different from the formation of low-mass stars, not just a matter of scale.
High-mass stars play an important role in the evolution of the universe through the release of heavy elements and the shock waves that occur when a massive star explodes in a supernova. Despite its importance, how massive stars form remains poorly understood due to their rarity.
To better understand the formation of massive stars, a team from the NAOC (National Astronomical Observatory of Japan) led by Kaho Morii, Patricio Sanhueza and Fumitaka Nakamura used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe 39 infrared dark clouds (IRDC).
IRDCs are massive, cold, dense clouds of gas and dust; and are believed to be the sites of massive star formation. The team focused on clouds that did not show signs of star formation, to understand the start of the formation process before young stars flare up. In the 39 clouds, the team found more than 800 star seeds, known as molecular cloud nuclei, that astronomers believe will become stars.
Their results are published in The Astrophysical Journal.
Of these cores, 99% lack sufficient mass to become high-mass stars, assuming high-mass stars evolve in the same way as low-mass stars, better understood. These findings support the idea that the formation mechanism of high-mass stars must be different from that of low-mass stars.
In addition, the team investigated the distribution of the nuclei. In star clusters, high-mass stars clump together, while low-mass stars are widely distributed. However, this work revealed that the locations of the highest mass nuclei do not show preference. compared to the positions of the nuclei of lower mass.
On the other hand, the densest nuclei tend to be locally concentrated. This suggests that denser nuclei, rather than more massive nuclei, may be the progenitors of high-mass stars; and that denser nuclei can grow more efficiently than less dense nuclei.
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