Supernova Remnants (6) ...

The principles of stellar life cycles are well represented by the following Hubble Space Telescope image, which captures many aspects of the cycle in a single view of a region of a nebula.

The image is of the nebula NGC 3603, which is a galactic H II (ionized hydrogen) region about 20,000 light years from Earth. Click on the "Show Labels" button to identify the following features (you may wish to click on the image to launch it in a separate window, which will make the comparison with the following list easier).

  • In the upper left center is the blue supergiant star Sher 25 that will probably soon become a supernova (we discussed this star previously in conjunction with Supernova 1987A). Around Sher 25 is a ring of ejected matter that may be related to the rings of ejected matter being illuminated in Supernova 1987A, and two lobes of bipolar outflow (upper right and lower left of Sher 25). The ring is about a light year in diameter.
  • To the lower right of Sher 25 (center of the image) is a brilliant cluster dominated by hot young O and Wolf-Rayet Stars. The ionizing radiation pouring out of this cluster has blown a bubble in the surrounding nebula so that the region around the cluster is almost clear.
  • Several giant pillars reminiscent of those seen earlier in the M16 Eagle Nebula can be seen to the right of the cluster. They are being eroded and shaped by the radiation coming from the cluster of hot stars in the same manner as the gaseous pillars of the Eagle Nebula. It is likely that star formation is going on inside these pillars.
  • The small, very dark clouds in the upper right are Bok Globules, which are thought to be an early stage of star formation.
  • In the lower left are two small objects that look like the protoplanetary disks (proplyds) that we have discussed earlier in conjunction with star formation in the Eagle Nebula. They appear to be 5-10 times more massive in this case, however. Their shapes and colors result from excitation and erosion by the intense flux of UV radiation emitted by the cluster of hot stars in the center.

    • This is a rather concise summary of stellar life cycles, from birth in molecular clouds to the formation of supergiant stars that will become supernovae and less massive stars that will enrich the interstellar medium through planetary nebulae, and back to nebulae enriched in the products of the previous generation of stars.