UW Researchers Receive Grants for Extrasolar Planet Studies

drawing of scientific equipment
This 3-D rendering of a spectrograph was created, using computer-aided design, by Michael Pierce, a UW associate professor of physics and astronomy. Pierce received a $175,000 grant from Indiana University to design and build the instrument, which provides a detailed chemical composition of the stars and measures the precise velocities, or speeds, at which the stars are moving. Hannah Jang-Condell, another UW associate professor of physics and astronomy, will conduct the hard science using the instrument through a $750,000 NASA grant. (Michael Pierce Photo)

Two University of Wyoming physics and astronomy researchers recently secured separate grants that will complement each other in the search for extrasolar planets.

Michael Pierce, a UW associate professor of physics and astronomy, received a $175,000 grant from Indiana University (IU) to design and build a spectrograph, an instrument used to obtain detailed information about star movement near planets. Using the spectrograph, colleague Hannah Jang-Condell will conduct the hard science with the aid of a $750,000 NASA EPSCoR (Established Program to Stimulate Competitive Research) grant. The NASA grant (about 40 percent) also will greatly enhance the capability of the spectrograph via a significant upgrade that will give the instrument the precision of detecting extrasolar planets, Pierce says.

A spectrograph separates light into a frequency spectrum and records the signal with the use of a camera. The instrument provides a detailed chemical composition of the stars and measures the precise velocities, or speeds, at which the stars are moving.

“I’m going to be using it to measure the radial velocity of stars to confirm whether there are planets around them,” says Jang-Condell, also an associate professor of physics and astronomy, who received her grant Dec. 1. “One of the methods of detecting exoplanets is to measure the Doppler shift effect as the star moves in response to a planet.”

The Doppler shift effect is the change in frequency or wavelength of a wave for an observer who is moving relative to the wave source. Pierce described it as “the tiny wiggle in a star’s speed created by a planet going around a star.”

The spectrograph eventually will play a key role in NASA’s Transiting Exoplanet Survey Satellite (TESS), which is expected to discover thousands of exoplanets in orbit around the brightest stars in the sky. Beginning next year, TESS will begin monitoring more than 200,000 stars for temporary drops in brightness caused by planetary transits.

While the TESS satellite will be able to detect, from space, planets around stars, the operation needs solid, ground-based research to determine if what TESS detects really are planets, Jang-Condell says. That’s where the spectrograph comes in.

Pierce’s grant, which started in November, is part of a contract with IU that will provide about $200,000 in equipment for the spectrograph, Pierce says.

Jang-Condell says about 40 percent of her NASA grant will go toward spectrograph equipment construction and other direct costs. The remaining 60 percent of her grant will cover the research and salaries of those who will conduct the science: Jang-Condell; Chip Kobulnicky, a UW professor of physics and astronomy; one postdoctoral researcher; one graduate student; and two undergraduate students.

Pierce will build the instrument at a lab within UW’s Physical Sciences Building. The instrument, when complete, will be placed on the telescope at the Wyoming Infrared Observatory (WIRO) on Jelm Mountain. Under the eight-year contract with UW, IU researchers will have access to the spectrograph for 15 days per year. As it will take him roughly three years to build, Pierce surmises IU scientists will be able to use the instrument for five years.

At approximately 1,000 pounds and measuring 3 feet by 6 feet, the spectrograph will be sealed in a vacuum to eliminate fluctuations in pressure and temperature, and it will be stabilized at 30 parts per million. The sensitive instrument can be thrown off by a change as small as one-thousandth of one degree, Pierce says.

“Otherwise, the instrument would expand and contract with temperature change. It would destroy its ability to measure movement of the stars,” he explains. “This is an exceedingly precise instrument. We’ll isolate it from the environment. We’ll operate it remotely from downtown.”

The instrument will be housed in a facility that will be built to connect with the existing observatory.

TESS will begin to make observations in the Northern Hemisphere in 2019. While the spectrograph may be built but not entirely sealed by that time, it will still be able to take good spectra of stars, even if the instrument is not yet ready to detect the Doppler shift effect or wobble of stars, Jang-Condell says.

“It will still help us characterize the properties of stars and help us understand the planets better,” she says.

“This instrument is very challenging to make, which makes it exciting,” Pierce says. “It allows our department to go in a different direction like this TESS project.”



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