Kirshner now thinks that other double supernovae are in existence. He says that since supernovae "probably do come from massive stars that form in clumps," it is "very likely" that double supernovae are "not so rare."

Kirshner says there may be other cases of a double supernova even in our own galaxy, but it would be a "50,000-year-old shell that we would hardly notice."

"Here, if we're right, there is a second event that is [relatively] young, and we can see change," he says. "It would be very interesting to see the effect of an explosion inside an explosion."

By studying supernovae, scientists can learn more about the creation of stars and other astronomical phenomena. "They can illuminate cosmic mysteries, like the size and shape of the universe."

Kirshner says one important reason to analyze these phenomena is because they are theorized to be the source of all heavy elements in the universe. When the stellar explosion takes place, it fuses all of the star's abudant light elements, like hydrogen and helium, into heavy elements, like iron. "There is a real sense that supernova elements are actually the physical origin of [the heavy] chemicals in our body," Kirshner says. The elements these supernovae create are in everything, he says, including "life, earth, iron and gold."

In a multiple explosion, though, it could be a "quite different physical situation," Kirshner says. If the explosions happen "together in space and time, the net effect could be larger," he says.

Although supernovae are said to "explode," in reality they start with a collapse, Kirshner points out. The inside of the star collapses to make what is also called a "neutron star" or "black hole" and this heats and eventually blows off the star's outer shells, thus spreading newly created substances throughout the universe.

Kirshner says another use for supernovae data is as a "yardstick for measuring the geometry of space." As they explode, supernovae are the brightest stars in the universe. By measuring its chemical and physical characteristics from its emitted light spectra, one can check to see if the universe is still expanding and at what rate, he says.

Kirshner also says places where supernovae have probably formed "might be the key to understanding what strong gravity really does," since explosion remnants are some of the most massive bodies in the universe.

Recent advances in technology have made observation for astronomers like Kirshner more effective. To take pictures of the light spectra of a supernova "it used to be photographic plates, but now we're using CCD's [Charge Couple Devise] that are the same that are in a home video camera." He says the CCD's are extremely sensitive to light and so are of immense use in detecting distant remnants.

Here at the CFA, where Kirshner has his office, researchers are mostly concerned with analyzing data picked up from tools like the CCD and the telescopes used in Chile, Kirshner says.

Future Studies

Early next month, Puppis A will be studied more extensively at Cerro Tololo. "We'll see if it stands up to closer scrutiny," Kirshner says, though he will not be in Chile for the continuing observation of his hypothesized double supernova, he says. Next semester he will be teaching the Core course, Science A-35, "Matter in the Universe," and says he needs to stay in town "for sectioning and stuff like that."

A former Quincy House resident, Kirshner received his doctorate in astronomy from Cal Tech and performed his post-doctorate work at Kitt Peak National Observatory in Tucson. Kirshner then worked at the University of Michigan as a professor of astronomy from 1976-1985, until he "received the call" to work at Harvard, he says.

Kirshner says he has worked with supernovae for the past 17 years, ever since he started his graduate work in California. But even as a junior concentrator in Harvard's undergraduate Astronomy Department, Kirshner decided to focus on his present specialty, when he took a tutorial on the Crab Nebula, a supernova remnant.

"I remember when I showed up at Cal Teach the first day, they asked me what I wanted to work on. I said, `I did some work on Crab Nebula, do you have any work on supernovae?' Some of these things are sort of thrust upon you."