Two teams of astronomers employed a technique for finding extrasolar planets to directly measure one such planet. The approach could enable the study of a lot more exoplanets’ atmospheres than ever ahead of.
A method astronomers have utilised for almost 20 years to indirectly find planets orbiting other stars has for the first time been used to take the direct measure of an extrasolar planet itself.
The approach not only yields precise estimates of a planet’s mass, a critical piece of info that can assist decide a planet’s bulk composition. It also can reveal its orbital inclination. And maybe most crucial, it could let astronomers to study atmospheres of a lot more extrasolar planets than ever ahead of.
The reason: The technique doesn’t require a star to backlight a planet’s atmosphere as the planet passes in front of its star. Till now, this kind of backlighting, throughout what is known as a transit, has supplied the only window astronomers have had on the make-up of an extrasolar planet’s atmosphere. And the number of transiting planets so far is only about one-third the number of planets discovered by two international teams of astronomers who used this approach and whose findings are published this month.
The orb the teams observed, known as tau Bootis b, was discovered in 1996 by a group led by astronomer Geoffrey Marcy at the University of California at Berkeley. It orbits a star practically 51 light-years from Earth in the Northern-Hemisphere constellation Bootes.
Marcy’s team located tau Bootis b via the slight wobble it imparted to its host star’s spectrum as it orbits. As the planet swings around its star and its gravity tugs the star away from the viewer, it slides the star’s bar-code-like chemical signature toward the red end of the spectrum. As the planet continues its orbit and tugs the star toward the viewer, the spectrum shifts toward the blue end. Over several orbits, the star’s spectrum “wobbles” from blue to red and back.
The idea to use this approach to detect a planet straight is an old one, notes Simon Albrecht, an astronomer at the Massachusetts Institute of Technology in Cambridge, Mass., and a member of one of the two teams. His group was led by Matteo Brogi with the Leiden Observatory in the Netherlands. The other team was led by Florian Rodler, with the Institute of Space Science in Barcelona.
All it required was the proper mixture of technologies and a target close enough and vibrant enough to pursue. Tau Bootis b fit the latter requirement. For hardware, both teams utilised a new, exquisitely sensitive near-infrared spectrometer bolted to the back finish of one of four eight-meter telescopes that make up the Extremely Big Telescope array. The facility, run by the European Southern Observatory, is situated on a mountaintop in the Atacama Desertof northern Chile.
Sources and more information:
• Extrasolar planets: List of exoplanetary host stars, List of extrasolar planets detected download
Extrasolar planets: List of exoplanetary host stars, List of extrasolar planets detected book download radial velocity, Gliese 581 c, HD 209458 b Download Extrasolar planets: List of exoplanetary host stars, List of extrasolar planets detected Extrasolar planet – Wikimedia . might find it in other star systems.
• Astronomers use an old trick to open new window on extrasolar planets