Posts tagged with: Science
Stellar Evolution: A Journey with Chandra
Three new images were recently added to the "Chandra X-ray Observatory" set on the Smithsonian Flickr Commons stream. Below, Kim Kowal Arcand, from the Education & Public Outreach group for the Chandra X-ray Observatory, explains the origins of these images. As noted on the Chandra site, the "flight operations, mission planning, data processing and user support for the Chandra mission are carried out by the Chandra X-ray Center at the Smithsonian Astrophysical Observatory (SAO) in Cambridge, Massachusetts." The Chandra X-ray Center is part of a NASA initiative to make its space programs more efficient by encouraging expert teams located outside NASA centers to assume expanded responsibilities.
The three new images recently added to the "Chandra X-ray Observatory" set on the Smithsonian Flickr Commons.When the Universe came into existence about 14 billion years ago, the only elements were hydrogen, helium, and traces of lithium, beryllium, and boron. The heavier elements did not yet exist. Heavy elements are produced by nucleosynthesis--the fusion of nuclei deep within the cores of stars. At some point in time, the first stars were formed, and within their cores the fusion process created heavier and heavier elements; the most massive stars produced nuclei as heavy as iron. When the stars used up their nuclear fuel, they started to evolve.
The evolutionary processes of stars depend upon their initial mass. Mid-sized stars eject planetary nebulae, leaving a white dwarf core remnant. More massive stars explode as supernovae, leaving neutron stars or black holes at the centers of the supernovae remnants. The elements that were created within the cores of the first stars were ejected into space where they intermingled with the surrounding interstellar medium. This medium--the gas and dust between the stars--provides the raw material for the formation of new generations of stars. Eventually, these elements became incorporated into large clouds of gas and dust that condensed and formed protostars. And so the cycle of stellar formation (see 30 Doradus) and destruction (see RCW 86 and G350.1+0.3) continues--each new generation further enriching the interstellar medium with heavy elements that become incorporated into the next generation. We are just beginning to understand stellar formation and destruction--and how the Sun, Solar System and life on Earth are connected to this never-ending cycle.
For a more complete picture of this journey, visit the Chandra X-ray Observatory's Field Guide to X-ray Astronomy: Stellar Evolution.
Discover more Chandra X-ray Observatory images on the Smithsonian Flickr Commons.
Residents of a Different Feather
Though today it holds a visitor’s center, exhibit space, and offices, the Smithsonian Institution Building, or "Castle," once also contained residential spaces. The Castle was home to the Institution’s first Secretary, Joseph Henry, and his family from 1855 to 1878. During the building’s early years it also included apartments for Smithsonian employees and visiting scholars.
But some other inhabitants of the Castle have been less conventional. In the late 19th century, barn owls took roost in the building's lofty towers. These uninvited occupants were nevertheless welcomed and were the object of study by researchers. The Smithsonian collections contain two owl eggs gathered from the roof of the Castle in 1861 and 1865 (specimens USNM B 9986 and 9693), the latter conserved by ornithologist, Spencer F. Baird, who would later become second Secretary of the Smithsonian. Ornithologists collected samples of the owls' pellets, droppings containing undigested remains of the rodents they ate, to study hunting habits. Another later Secretary and ornithologist, Alexander Wetmore, gathered over two thousand pellets from the Castle towers while working for the Biological Survey in 1913.
Though the owls were useful study subjects, they were at some times pests. Residents of the Castle noted that the owls often crashed into their windows, startling them from their work. When the owls would dive to catch prey at night they would nearly collide with superstitious guards who patrolled the National Mall and took the swooping birds to be curses of bad luck. The guards complained to sixth Secretary Wetmore during his tenure from 1945–1952 and asked that he remove the owls, but he wittily replied that "our guards must remain dauntless to any and all attacks." However, by the 1950s the owls had outstayed their welcome. A large quantity of droppings that had accumulated had generated an unpleasant smell and caused the floor of one tower to collapse. The owls were put out and the windows were barred.
But in 1971, eighth Secretary S. Dillon Ripley, yet another ornithologist interested in the tower owls as much as his predecessors, decided to reinstate the winged residents. He believed that the owls could hunt the rats attracted by the newly placed garbage cans on the National Mall. Ripley argued that the owls would be beneficial "for reasons of biological harmony as well as tradition." He wrote to former-Secretary Wetmore inquiring about the history of the tower owls, and set about equipping replacements. Barn owls to be put in the towers were trained at the National Zoological Park to breed in captivity and hunt live prey. In 1974, a male and female were placed in the northwest tower of the Castle. Alex (named for Wetmore) and his mate Athena were fed dead lab rodents and soon hatched seven young owlets.
Once the observers felt that the owls were comfortable in their new home, they unbarred the windows. But by December 1975 the last of the owl family had, quite literally, flown the coop. Not to be deterred, Ripley commissioned a second pair of trained owls from NZP, this time named "Increase" and "Diffusion" for language found in the Institution’s bequest (under a clause in his will, the Institution’s founding donor, James Smithson, left his fortune to the United States to found under the name of the Smithsonian Institution, "an establishment for the increase and diffusion of knowledge among men."). The aptly-named owl duo was placed in the tower in January 1977, and hatched three young owlets that spring. However, when given the chance to fly to freedom, the second family also took to the air never to return to the Castle tower.
Now the towers are uninhabited. And though Ripley was saddened by the lack of traditional residents, those who had to tend to the owls probably were not. Writing in 1993, one such caretaker remembers climbing the ladder to place a bag full of dead rodents in the coop, dressed in a protective suit and helmet to guard against (as Ripley put it) "more than a gentle tap" on the head. Ripley himself once received an aerial attack when, while poking his head in to take a look at the birds, an owlish deposit fell squarely in his eye.
Earth Day
The first Earth Day was held on April 22, 1970, and was organized by Gaylord Nelson, US Senator from Wisconsin, to raise environmental awareness in the United States. By 1990, Earth Day went international with 200 million people participating in events in 141 countries.
Leading up to an Earth Day 1990 conference, the Smithsonian held a conference in September 1989 between media professionals and scientists to encourage new strategies in reporting critical environmental stories in the news. Covering the Environment: Front Page or Yesterday's News? is a thirty minute video based upon these discussions, which was only distributed to media professionals.
The chairmen for the discussion were Senators Timothy E. Wirth and John Heinz. Some of the participants included biologist and ecologist Paul R. Ehrlich, Stanford University; atmospheric chemist Susan Solomon, National Oceanic and Atmospheric Administration; environmental biologist Stephen Schneider, National Center for Atmospheric Research; television journalist Lesley Stahl, CBS News; television journalist and correspondent Andrea Mitchell, NBC News; and executive editor Ben Bradlee, Washington Post.
Another participant was biologist and researcher Edward O. Wilson of Harvard University. In the clip below Wilson talks about the need for a "world survey of species" and "a complete biotics inventory." In 2007, the Encyclopedia of Life (EOL) began with a mission to create an online species database, of which the Smithsonian is one of the five original cornerstone institutions. While a 2007 TED speech by Wilson served as a catalyst for the creation of the EOL, Wilson clearly had been thinking about the idea for awhile.
Lastly, Thomas E. Lovejoy, Assistant Secretary for External Affairs at the Smithsonian at the time (and also responsible for introducing the term "biological diversity" to the scientific community), gives us some final thoughts about the environment.
The Smithsonian continues its interest in the issues at the core of Earth Day. One of the four grand challenges in the Smithsonian’s current strategic plan is: "Understanding and Sustaining a Biodiverse Planet," and to this end, the Smithsonian will work to "advance our knowledge and understanding of life on Earth, respond to the growing threat of environmental change, and sustain human well-being." Celebrate Earth Day 2012 with the Smithsonian, where several museums including the National Zoo and the National Museum of the American Indian, will be hosting events.
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