Cosmos: A Spacetime Odyssey Episode 8: “Sisters of the Sun” — Women, such as Annie Jump Cannon, have also made significant contributions to astrophysics. This episode is dedicated to them.I’m not sure why it took eight episodes into Cosmos: A Spacetime Odyssey to start talking about women and their contributions to astrophysics, but here we are. This week’s episode also touches on what we understand about stars. Let’s start with how women and stars intersect: the Pleiades.
The Pleiades Legend 1
The Pleiades, a cluster of stars in the Taurus constellation, is one of the easiest to spot with the naked eye from earth. Also known as the Seven Sisters, there are some legends associated with their origin. One North American version involves seven women from a tribe dancing under the night sky. As they danced, bears tried to attack the group. The women ran to a rock formation and called to the heavens for help. The rock formation rose out of the ground, lifting the women to the stars and creating what is now known as Devil’s Tower.
The Pleiades Legend 2
The ancient Greeks also had their own myth about the star cluster. The daughters of Atlas would cavort and caper while Orion watched through the bushes. He would pursue the women, none of whom were interested in the hunter. Zeus got involved and “protected” the women by turning them into stars. Of course, the constellation of Orion can be seen watching the Seven Sisters in the night sky. Zeus is a jerk.
At Harvard in 1901, Edward Charles Pickering employed “computers” to help with the categorization of stars. Those computers, also known as Pickering’s Harem, included Annie Jump Cannon and Henrietta Swan Leavitt, both of whom were deaf. Cannon’s system of categorizing the stars used a variation of spectrometry to place stars in one of seven areas. The star’s intensity was used to place a star into one of ten subcategories. Not only did this bring order to the chaos of the cosmos, but Cannon’s work provided the foundation for an important discovery.
Cecilia Payne came to the United States from England back in 1923 to work with Pickering’s Computers. Following a lecture by Henry Norris Russell, an astronomy bigwig who thought the sun and the earth shared the same composition, Payne tested out some hypotheses. Using Cann0n’s categorizations, Payne discovered that the seven categorizations revealed variations in temperature between stars. Russell, who was Payne’s advisor in her PhD process, thought her findings were flawed. Sadly, Payne accepted her advisor’s critique and included a disclaimer at the end of her thesis. The good news: Russell reevaluated the science four years later, retracted the disclaimer, and made sure Payne got the credit. Woo!
Our stellar tour ends with a visit to the Carina Nebula, which is about 7,500 lightyears away. Star activity here pushes the upper limits of star formation. As a star ages, the size of the star will expand. Our sun, for example, will eventually grow to the size of a red giant, swallowing Mercury, Venus, and possibly our planet.1 Eventually, the core of the sun will not be able to support further expansion, causing the star to collapse, or nova. The gases and elements will blow apart, leaving the core as a white dwarf. The materials blown off will eventually catch in some other body’s gravity.
In the Carina Nebula, the stars are close enough to each other that when a star novas, the materials are captured relatively quickly. The stars grow larger with each explosion. Eventually, Ada Carina will be so massive, when it explodes (if it hasn’t already) it will make a supernova seem like popped bubblewrap. We’re talking scraping the paint off the walls (or in cosmic terminology: stripping away atmospheres). We’re far enough away so that we won’t feel the effects, but it’s a good thing to keep in mind in case you’ll be traveling in the next few millennia. Thanks to the work of Cannon, Leavitt, and Payne, we know to look for this sort of activity in the cosmos.
- Don’t worry, this is billions of years from now. ↵