An international team of scientists has secured a large program of nearly 200 hours of observing time with NASA's Hubble Space Telescope to explore the atmospheric conditions of planets outside our solar system, known as exoplanets.
The research will focus on "Hot Jupiters," exoplanets similar in size to Jupiter, but with temperatures of 1,000 degrees Kelvin (1,340 degrees Fahrenheit) or more because they orbit so closely to their respective stars.
Large programs using the Hubble Space Telescope historically have led to data sets with a lasting legacy. The team is led by David Sing, who obtained his doctorate at the University of Arizona working in the departments of physics, astronomy and planetary sciences and is now at the University of Exeter in the U.K.
Gilda Ballester, an associate staff scientist at the UA's Lunar and Planetary Laboratory who is one of the researchers participating in the project, said securing an observation program of this magnitude is an outstanding feat for a researcher at the beginning of his career.
"Data gathered using the Hubble Space Telescope will tell us more than ever before about the atmospheric composition of these planets outside our solar system," Ballester said. "So far, only two extrasolar planets have been observed in some detail in the visible light spectrum with Hubble."
"We are going to study eight, exploring for the first time the full diversity of Hot Jupiter atmospheres and identify important physical processes common to the entire class of these planets."
The planets to which the team will point Hubble vary in mass (from one-fifth to one and one-half times the mass of Jupiter), radius (one to twice that of Jupiter) and temperature (1,300 to 4,600 degrees Fahrenheit).
According to Ballester, Hot Jupiters orbit their star at very close range, and their rotation is synchronous to their orbit, meaning the same side always faces the star, much like the moon always points the same side at the Earth.
This makes for a lot of heating and for interesting dynamics, for example how the intense energy streaming onto the planet's exposed side is distributed around the planet.
If the Earth orbited the sun as closely as a typical Hot Jupiter, the star would dominate the sky to an imaginary observer looking up from the planet's point closest to the star. The opposite side would be plunged in eternal darkness.
Ballester said the typical distance of a Hot Jupiter to its star is a mere 2 to 5 one-hundredths of the distance between the Earth and the sun. And unlike Earth, which takes a year to complete its orbit around the sun, Hot Jupiters complete the journey in only one to five days.
By understanding the chemical make-up of exoplanet atmospheres around eight Hot Jupiters and perfecting the difficult techniques needed to make these precise measurements, the researchers will also help prepare for future searches for life on exoplanets.
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