麻豆淫院

The Atacama Large Millimeter/submillimeter Array (ALMA) has uncovered a key piece of the puzzle in how rocky planets, such as Earth, form around young stars. For decades, scientists have struggled to explain how dust grains in the disks around newborn stars grow from tiny dust grains to planet-building "pebbles" without either spiraling into the star or shattering in collisions鈥攁 challenge known as the "meter-size barrier."

A team of more than 50 astronomers and chemists from the world's leading scientific institutes used ALMA for this large program of research, known as the "Fifty AU STudy of the chemistry in the disk/envelope systems of Solar-like protostars" or FAUST. The team studies the chemistry of the dense molecular gas in the envelopes of a representative sample of solar-like protostars, and now, for the first time ever, have directly observed millimeter-sized dust grains鈥攁bout 10,000 times larger than typical interstellar dust鈥攅mbedded in the walls of a protostellar outflow cavity.

These grains appear to have been lifted from the dense inner protostellar disk by winds and then deposited farther out, away from where they can fall back onto the disk, and continue growing. This process gives the grains more time and space to stick together, potentially overcoming a long-standing barrier to planet formation.

Astronomers directly observed these millimeter-sized dust grains in the walls of the protostellar outflow cavity of the young L1551 IRS5 binary system, showing these grains can grow much larger than previously thought in the early stages of planet formation. These findings, in the journal Astronomy & Astrophysics, offer new insight into the processes that may have led to the formation of our own solar system and highlight a previously underestimated pathway for planet formation.

"This discovery not only provides a new mechanism for building planets but also offers a glimpse into how our own solar system may have formed," said Giovanni Sabatini, a scientist with the National Institute for Astrophysics (INAF) at the Arcetri Astrophysical Observatory in Florence, and leader of this research.

"The findings open exciting new questions about the diversity of planetary systems in our galaxy and bring us closer to understanding our cosmic origins," adds Claire Chandler, NSF NRAO scientist and a co-PI of the FAUST collaboration.