Young Astronomers at Work
A supernova is a stupendous explosion that happens when a massive star runs out of fuel. Without the outward pressure of nuclear fusion to support the star, it collapses, its iron core rebounds, and the energy that's released makes it as luminous as an entire galaxy.
There are also Type Ia supernovae that start with a star that's already dead. A white dwarf is the remains of a medium-sized star that's used up its nuclear fuel. If it has a binary companion, the dwarf can pull material away from it, giving it enough mass to restart nuclear fusion. But it's not a steady burn, it's a runaway chain reaction which releases all of the energy in a few seconds.
Supernovae are transient objects. They don't last. They brighten suddenly and then fade over time. So in searching for a supernova, you're looking for something new in the sky. Computer software now helps because it can "blink" between two pictures to highlight anything that isn't in both pictures.
The Gray Family
One Canadian family has a knack for finding supernovae. By 2010, when Paul Gray's daughter Kathryn got interested in supernovae, Paul had already discovered six of them. He showed her how the software worked and directed her to photographs from his friend David Lane's observatory. Kathryn did spot something, and she shares the discovery credit with her father and David Lane. The International Astronomical Union (IAU) designated it SN 2010t, a Type Ia supernova.
Kathryn, aged 10, became the youngest person to discover a supernova. She was also the inspiration for her younger brother Nathan to get involved. On October 30, 2013, he found a previously unknown supernova candidate. It's since been officially confirmed by further observation with large telescopes. Nathan is now the youngest to discover a supernova. Although he was also ten, he was about a month younger than Kathryn was when she made her discovery.
A supernova leaves something behind besides an expanding debris cloud. It also leaves an unbelievably dense body called a neutron star. Although a neutron star is only about 20 km in diameter, it's more massive than the Sun. If a teaspoonful of neutron star matter could be brought to Earth, it would weigh millions of tons.
Some neutron stars spin and emit powerful beams of radiation, which we can detect when they point in our direction. Like seeing the beam of a lighthouse, we detect a regular series of pulses, so they are called pulsars. Some take a few seconds to spin, others – millisecond pulsars – may spin hundreds of times per second. The light beams aren't visible, but are detected in radio waves, x-rays or gamma rays.
Green Bank and schools
The US National Radio Observatory has a large telescope at Green Bank, West Virginia. Along with West Virginia University and support from the National Science Foundation, they run the Pulsar Search Collaboratory. It works with teachers and high school students to analyze data from the radio telescope. They provide the data and train the teachers, who then teach students how to distinguish pulsars from other signals and background noise. If a result looks good, it's confirmed on the telescope.
Two girls at the same Kentucky school have discovered previously unknown pulsars while taking part in the program. Hannah Mabry found a pulsar in 2011, sharing the credit with two Virginia students, Alexander Snider and Casey Thompson. Almost exactly a year later, Hannah's friend Jessica Pal and Virginia student Emily Phan discovered a millisecond pulsar. The experience of doing real science has encouraged the students to study science further.
Can Jupiter's light make shadows?
You can see your own shadow in sunlight and maybe you've noticed shadows in bright moonlight. Apparently, the light of Venus and the Milky Way can make shadows. But what about Jupiter? Laurent V. Joli-Coeur of Montreal, Canada was intrigued enough by this question to investigate. Laurent is a keen amateur astronomer and prize-winning astrophotographer.
You'd need something to cast the shadow, a good camera to get a long exposure, and a very dark sky. Laurent got some help in making an apparatus to test the idea. The camera was fixed inside it to take timed exposures. It could be pointed towards Jupiter to get its light to fall on a gnomon – that's the bit on a sundial that sticks up to make the shadow.
The gnomon did cast a shadow. And if Laurent rotated the “Jupiter dial”, the shadow moved appropriately. In order to see if a general sky glow were creating the shadow, he also pointed the dial to avoid light from Jupiter. There was no shadow.
In May 2012, five hundred young people took part in the Canada-Wide Science Fair. As the first person ever to photograph a shadow created by Jupiter light, 15-year-old Laurent Joli-Coeur received the Best Project Award.
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