Early Dust Formation

NASA Satellites Spot Young Star in Growth Spurt

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Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.


This illustration shows a young star undergoing a type of growth spurt. Left panel: Material from the dusty and gas-rich disk (orange) plus hot gas (blue) mildly flows onto the star, creating a hot spot. Middle panel: The outburst begins – the inner disk is heated, more material flows to the star, and the disk creeps inward. Right panel: The outburst is in full throttle, with the inner disk merging into the star and gas flowing outward (green). Credit: Caltech/T. Pyle (IPAC)


An adolescent star in the midst of a dramatic growth phase has been observed with the help of two NASA space telescopes. The youngster belongs to a class of stars that gain mass when matter swirling around the star falls onto its surface. The in-falling matter causes the star to appear about 100 times brighter. Astronomers have found only 25 stars in this class, and only about half of those have been observed during an outburst. 

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Ancient Stardust Sheds Light on the First Stars

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This research was presented in a paper entitled “Dust in the Reionization Era: ALMA Observations of a z =8.38 Gravitationally-Lensed Galaxy”
by Laporte et al., to appear in 
The Astrophysical Journal Letters.

This artist’s impression shows what the very distant young galaxy A2744_YD4 might look like. Observations using ALMA have shown that this galaxy, seen when the Universe was just 4% of its current age, is rich in dust. Such dust was produced by an earlier generation of stars and these observations provide insights into the birth and explosive deaths of the very first stars in the Universe. Credit: ESO/M. Kornmesser
Astronomers have used ALMA to detect a huge mass of glowing stardust in a galaxy seen when the Universe was only four percent of its present age. This galaxy was observed shortly after its formation and is the most distant galaxy in which dust has been detected. This observation is also the most distant detection of oxygen in the Universe. These new results provide brand-new insights into the birth and explosive deaths of the very first stars.

An international team of astronomers, led by Nicolas Laporte of University College London, have used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe A2744_YD4, the youngest and most remote galaxy ever seen by ALMA. They were surprised to find that this youthful galaxy contained an abundance of interstellar dust — dust formed by the deaths of an earlier generation of stars.

Follow-up observations using the X-shooter instrument on ESO’s Very Large Telescope confirmed the enormous distance to A2744_YD4. The galaxy appears to us as it was when the Universe was only 600 million years old, during the period when the first stars and galaxies were forming [1].


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