HEAPOW: Burning In from the Outside? (2014 Jun 09)
Stars are usually born in groups from clouds of gas and dust distributed throughout the galaxy. Star formation features a complex interplay between gravity, rotation, and heat. A common idea among astronomers is that star formation proceeds from the center of a cloud to its outskirts, burning through the cloud from inside to outside. But new data are challenging that idea. The image above shows a composite X-ray and infrared image of a young cluster, NGC 2024, at the heart of the Flame Nebula. The X-ray data (from the Chandra X-ray Observatory, in purple) and the infrared image (from the Spitzer Space Telescope) let astronomers peer deep within the cluster to obtain a near-complete census of the newborn stars. And what they found was surprising: instead of finding the firstborn stars in the center of the cluster, the Chandra and Spitzer data show that the oldest stars are actually found in the outskirts of the cluster, and younger stars in the center. This could mean that star formation begins in the outer part of the nebula and proceeds towards the center of the cluster. A more likely explanation is that star formation actually begins at the center of the nebula, but, because of the high gas and dust density in the center, continues on for millions or billions of years, while it shuts off earlier in the outer parts of the star-forming cloud.
Chandra: Inside the Flame Nebula
CXC: Flame Nebula: New Insight into Formation of Star Clusters
Age Gradients in the Stellar Populations of Massive Star Forming Regions Based on a New Stellar Chronometer - Konstantin V. Getman et al
- Astrophysical Journal 787(2) 108 (2014 Jun 01) DOI: 10.1088/0004-637X/787/2/108
arXiv.org > astro-ph > arXiv:1403.2741 > 11 Mar 2014
- Astrophysical Journal 787(2) 109 (2014 Jun 01) DOI: 10.1088/0004-637X/787/2/109
arXiv.org > astro-ph > arXiv:1403.2742 > 11 Mar 2014
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