Stellar nursery

Fig. 6.1. Stellar nursery in the constellation of Orion. Molecular clouds A and B were detected by their radio emissions. They appear to have given birth to several generations of stars (la, It and Ic).

Kant was essentially correct, Bob says. In the last years of the twentieth century, the Hubble Space Telescope (HST) revealed several dozen disks at visible wavelengths in the Orion Nebula, a giant stellar nursery about 1,600 light years away. We call them proplyds, a contraction of the term protoplanetary disks. The Orion proplyds are larger than the Sun s solar system and contain enough gas and dust to provide the raw material for future planetary systems (figure 6.1). 

Bob leans back in the Naugahyde chariot seat. Stellar evolution refers to what happens to stars as they get older. We can use the H-R diagrams I already told you about to visualize this. In our twenty-first century, stars were born all the time in huge clouds of gas and dust called nebulae. Think of these clouds as stellar nurseries. One of the most famous is the Orion Nebula (figure 5.5). 

With the death of its stellar nursery, a newly-born nucleus commences its fascinating journey to our Solar System. It will first capture electrons to become... 

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