In its first months of operation, the Lick Observatory's newest telescope Automated Planet Finder (APF) has found two new planetary systems, giving astronomers a taste of planetary riches to come. The APF has been operating robotically night after night since January, searching nearby stars for Earth-sized planets. Every night the fully autonomous system checks the weather, decides which stars to observe, and moves the telescope from star to star throughout the night, collecting measurements that will reveal the presence of planets.
The search for planets beyond our solar system (called "extrasolar planets" or "exoplanets") has yielded a huge number of discoveries in recent years, especially since NASA's Kepler spacecraft joined ground-based telescopes in the effort. Unlike Kepler, however, which focused on distant stars in one small patch of sky, the APF focuses on nearby stars and covers the entire sky.
"The planetary systems we're finding are our nearest neighbors. Those are the ones that will matter to future generations," said Steve Vogt, professor of astronomy and astrophysics at UC Santa Cruz, who led the $12 million APF project and designed the Levy spectrometer at the heart of the system. Vogt's team has submitted two papers describing new planetary systems recently discovered by the APF.
The APF facility consists of a 2.4-meter telescope and the Levy Spectrometer, which Vogt designed and optimized specifically for planet hunting. The spectrometer takes starlight from the telescope and spreads it into a rainbow of colors, splitting the light into a spectrum of thousands of different wavelengths that can be measured with great precision. Repeated measurement of a star's spectrum enables astronomers to detect the tiny wobble induced in a star by the gravitational tug of an orbiting planet.
"Steve Vogt has a long history of breaking barriers in the design and construction of the world's most sensitive and precise spectrometers. This time, he has outdone himself," said APF co-investigator Geoffrey Marcy, professor of astronomy at UC Berkeley. "With the Automated Planet Finder, he has not only built a highly efficient and precise planet-hunting spectrometer, but he also led the construction of the world's first robotic telescope tuned finely enough to feed such a spectrometer."
Last year, Marcy suggested that concentrated laser light in the universe may singal the presence of a technological civilizations that might be living on distant planets. “Think about humanity 300 hundred years from now,” said Geoffrey Marcy this past August. Marcy is currently Professor of Astronomy at the University of California, Berkeley, famous for discovering 70 out of the first 100 exo planets. “Suppose we set up a colony on another planet … the most likely way we will communicate with (humans on those planets) is with radio signals or light beams.” Marcy believes that there may be other civilizations in the universe that are years ahead of human society and might currently be communicating with radio signals in a network he calls a “galactic Internet.”
The vast majority of planets reveal themselves over time through a series of measurements, and the signals are buried in the huge stream of data that comes back from the telescope every night, so this software package is an integral part of the detection process. The APF is the best current planet-finding instrument that can see the sky above our hemisphere. It's remarkable that this cutting-edge research can be done within sight of Silicon Valley--you don't have to go to Hawaii or Chile.
Vogt also designed spectrometers for the Keck I Telescope in Hawaii and Lick's Shane Telescope--both of which have been highly productive planet-finding instruments. In many ways, however, the APF is a more powerful planet finder than even the 10-meter Keck telescope because the APF was custom-built for that purpose, Vogt said. The precision with which the APF can measure the motion of a star is much better than can be achieved at Keck. The APF's telescope is relatively small, but with modern optical technology, including special coatings on the mirrors, its optical efficiency is very high.
"We can do the same work we did at Keck, except now we have the APF every night instead of just a few nights per month at Keck," Vogt said. "What we're learning from all of this--from Kepler and from our own work--is that there's a huge number of planets out there, more planets than there are stars, and they're everywhere, including right next door to us."
The APF will also be useful for a wide range of conventional astronomical observations involving spectroscopy, including follow-up observations of bright supernova explosions and gamma-ray bursts that may brighten and dim quickly. "The robotic APF can wheel over to these stupendous cosmic explosions within seconds to allow spectroscopic analysis of their brilliant flash of light," Marcy said.
About 20 percent of the APF's time is set aside for purposes other than planet finding, with access to be allocated by the director of UC Observatories. The rest of the observing time is divided equally between the planet search teams led by Vogt and Marcy.
“I am not an optimist,” Marcy said, describing the likelihood of finding intelligent extraterrestrial life. “I would bet on my house that we would fail … But this is such an important question, the question of ‘Are we alone?’, and the only way to find out is to risk it.”
Artist's rendering of the planetary system at the top of the page shows HR 8799 discovered in 2013. The planets orbiting HR 8799 weigh in at between five to 10 times the mass of Jupiter and are still glowing with the heat of their formation, allowing researchers to directly image them.
"It's the only system in which multiple planets can individually be seen," said study co-author Bruce Macintosh, an astronomer at Lawrence Livermore National Laboratory in California. The planetary system resembles a scaled-up version of our solar system, suggesting there may be smaller Earth-size planets closer in, although the researchers currently have not yet seen any. The HR 8799 system is home to four giant planets orbiting a relatively young, 30-million-year-old star, with each planet far larger than any world found in Earth's solar system.Image credit: http://dunlap.utoronto.ca/
The Daily Galaxy via http://www.dailycal.org/, http://news.ucsc.edu/2014/03/apf-telescope.html
Image credit: http://dunlap.utoronto.ca/