John Debes

NASA postdoctoral researcher scans the skies for clues to planetary development

Dr. John Debes will likely never realize his dream of interstellar space travel or traversing other planets. But Debes is still reaching for the stars.

He is participating in research as part of the NASA Postdoctoral Program, which is administered by Oak Ridge Associated Universities at the Goddard Space Flight Center in Maryland.

“I like to understand how planets form and evolve through all stages of a star’s life,” Debes said, who is in the third and final year of his fellowship at Goddard.

Debes, who hails from York, Pa., said his research offers clues about Earth’s past, present and future by focusing on interpreting the light scattered off dust in disks around young stars.

“You can boil it down to ‘where did we come from, and where are we going?’” Debes said. “The way I do that is by studying young, dusty disks to understand what they’re made of, and also by studying planetary systems around white dwarfs, which are essentially the corpses of sun-like stars.”

Debes explained that young, dusty disks are small bits of dust around stars that have just formed dusty white dwarfs.

“I think my favorite part of the research right now is looking for dusty white dwarfs with the WISE [wide-field infrared survey explorer] telescope.”

The high-density, small-radius white dwarfs are what stars like our sun evolve into after they have exhausted their supply of nuclear fuel.

He added that dusty white dwarfs are those same leftover cores that for some reason have dust discs around them—much like the rings around Saturn.

Debes, who received an undergraduate degree in physics from Johns Hopkins University and earned his Ph.D. from Penn State University, said our planetary system has lots of company in the vast expanses of deep space.

“Radial velocity, transit, astrometry and direct-imaging searches have turned up about 400 or so planets in our local galaxy, which implies that at least 10 to 20 percent of stars have some kind of planet. If you figure that there are many billions of stars in our galaxy, it is not unreasonable to expect that there are millions of planets in our own galaxy. Planets are being formed all the time; we just don’t know exactly where yet,” Debes said.

“A good example of a ‘recent’ planet is the one discovered around the star Beta Pictoris. Beta Pictoris has a dust disk and shows evidence of its surface being bombarded by hot, evaporated comets. It is around 10 million years old, which is about as young as a planetary system can get.”

Of particular note, he discovered that the debris disks around stars can be sculpted by interactions with gas in the interstellar medium, which is gas and dust that resides between stars in our galaxy.

Debris disks occur when planets form. They collide and generate so much dust that you can actually observe it. The dust forms in disks that astronomers call debris disks, because they’re the “debris” from repeated collisions between asteroids and comets.

Debes is using NASA’s powerful WISE telescope to study all known white dwarfs for signs of such dust, which will hopefully increase the number of known disks by an order of magnitude.

Debes said his research is the fulfillment of childhood dreams.

“I have wanted to be some kind of scientist all of my life, starting with a very intense interest in dinosaurs and paleontology that started when I was about four. My parents encouraged whatever learning or reading I was interested in, taking me to the Academy of Natural Sciences Museum or the Franklin Institute in Philadelphia as often as I asked.

“My interest in science fiction spurred a keen desire to travel to other planets, and when I saw images from the Hubble Space Telescope in a high school astronomy class, it seemed the closest I would personally come to science fiction.”

But sometimes, youthful aspirations are realized.

Thanks to his research, Debes has an up-close-and-personal window to our galaxy as he searches the skies for clues to the secrets of planetary development.