Astrophysics student pieces together a celestial puzzle
Dec. 13, 2012
by Susan Gawlowicz
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David Principe pieces together pictures of young stars, wavelength by wavelength and across the electromagnetic spectrum. Multiple sources of information contribute details to his understanding of star formation.
“Optical light is only a small part of the whole picture,” says Principe, a doctoral student in RIT’s astrophysical sciences and technology program from Mentor, Ohio. “Light emitted by young stars consists of components of the full spectrum—radio, infrared, optical, ultraviolet and X-ray. Just one of these wavelength domains doesn’t always give you the full picture of the underlying physics.”
Principe is a member of the Laboratory for Multiwavelength Astronomy in the College of Science. Directed by Joel Kastner, professor in the Chester F. Carlson Center for Imaging Science and Principe’s thesis adviser, the lab consolidates related research by likeminded faculty, staff and students who participate in the Astrophysical Sciences and Technology doctoral program offered through the School of Physics and Astronomy.
Multiwavelength astronomy broadens Principe’s perspective when looking for stars on the cusp of formation—the elusive “Class 0” protostar— embedded in molecule-rich clouds. He will obtain data on three candidate protostars using NASA’s Stratospheric Observatory for Infrared Astronomy, also known as SOFIA. Principe won time in the upcoming year on the telescope’s first observation cycle. The observatory will image regions of space he specified, including the Orion B molecular cloud complex, a stellar nursery located 1,500 light years away from Earth.
Principe is curious about the disks of gas and dust that orbit and nourish protostars and other young stars in early development. Astronomers suspect the dependent protostars have strong magnetic fields that channel material from their disks, he explains.
“We expect Class 0 stars to be magnetically active, and therefore emitting X-rays, but we haven’t detected very many of them and astronomers are asking why.”
He suggests two scenarios: Either the surrounding disks absorb X-ray emission or the magnetic fields are dormant at the protostar stage.
Principe will compare the new infrared data with observations from the archives of NASA’s Spitzer Space Telescope and Chandra X-ray Observatory. Existing Spitzer infrared data for a trio of X-ray-bright protostar candidates have already provided him with useful reference at short wavelengths. But the three objects merge into an indistinguishable “blob of light” at longer infrared wavelengths.
“We already know of a potential X-ray-emitting Class 0 star, but we need SOFIA images to prove that it’s in its very earliest stage,” Principe says.
The new observatory’s 2.5-meter telescope will enable Principe to measure the brightness of each protostar at longer infrared wavelengths. These mid- to far-infrared brightness measurements, combined with shorter-wavelength Spitzer data, will reveal which of the three X-ray-emitting objects, if any, are cool enough to be Class 0 protostars.
Principe hopes to establish the extreme youth of at least one of these protostars in the infrared and connect them with the active magnetic fields visible to Chandra as X-ray emission sources. Confirmation of a Class 0 protostar that emits X-rays would help shape current astronomical theories on star formation by establishing the importance of magnetic fields at the earlier stages of the process, Principe says.