Stars, planets, quasars, black-holes, nebulae and galaxies. These are the macroscopic objects that make up our expanding universe. Until now, humanity has never known whether its existence was a fluke or if there are many planets like ours in the universe.
After a 16-year-long project to find an “Earth 2.0,” Steve Vogt, UC Santa Cruz astronomer and professor of astronomy and astrophysics, and his project team have found an irrefutable “super-Earth,” a planet that has characteristics similar to those of Earth.
Discovered in 2010, the super-Earth Gliese 667Cc is perfectly situated in the habitable zone of a triple-star system 22 lightyears away. The planet is named for German astronomer Wilhelm Gliese, who catalogued many of the nearby stars Vogt and others have been exploring.
Some of these characteristics of a super-Earth include the planet’s position in its solar system, whether it is of a similar size, and whether or not it is a rocky planet as opposed to a gas giant. Most of these super-Earths are too close to their sun, making them too hot to inhabit, much like the planet Mercury in our system. What makes Gliese 667Cc different from these other super-Earths is the possibility of life on its surface.
“This is the first earth-sized, potentially habitable planet that we know of,” Vogt said.
It is almost unequivocal that there is life on these planets, Vogt said, and the main goal of astronomers in the past 20 years has been to find that life by looking at the stars and searching for super-Earths.
“Since the beginning, it’s been very clear that the end-game of all this is to find another Earth,” he said.
Gliese 667Cc represents but one answer to the great cosmic puzzle. The diverse research of the astrophysics faculty at UCSC opens many roads to discovery to answer the questions humans have asked since they first looked up at the sky. While these questions are seemingly infinite, the search for planets provides a start.
“What used to set humans apart from other animals was curiosity,” said Paul Butler, a member of Vogt’s project team. “Where do we come from? How did we get here? Is there are reason why we are here? Are we alone? These are the fundamental questions of astronomy — this is why astronomy is historically the first science.”
Butler is a pioneer in the search for exoplanets, or planets outside Earth’s solar system. He said the search for super-Earths is essentially the search for our very humanity, our origin and our place in the universe, and the loss of our curiosity is the greatest threat to discovering the answers to these heavy questions.
“It would not occur to previous generations to ask why people study the sky,” Butler said. “As people withdraw from the natural universe into their iPod, PlayStation 3D and Siri cocoons, this is becoming an increasingly common question. While we won’t be around to see the end results of this work, this is nonetheless why we get up in the morning.”
Vogt said the characteristics of the planet and its place in the solar system indicate a strong possibility of life on its surface.
Because Gliese 667Cc is an M-class dwarf star, it does not emit as much light or energy as our G-class sun does. 667Cc has to be very close to the star itself to be in the habitable zone, Vogt said. Since the planet is so close to its sun, they are in a synchronized orbit. This means 667Cc has a light and a dark side, much like our moon.
“If there were organisms on the planet, they would probably hang out on the band in between the light and dark side, the twilight zone,” Vogt said. “It’s like an ecological buffet: There are hot ecosystems, icy ecosystems and everything in between.”
Vogt called Gliese 667Cc “the real deal.” A previous super-Earth found by Vogt and his team, Gliese 581g — also named Zarmina’s World, after Vogt’s wife — has been disputed. Some people doubt Gliese 581g was the first habitable planet discovered since the High Accuracy Radial velocity Planet Searcher (HARPS) Swiss group disputed its discovery in 2010. Vogt and his team have stood by their discovery, as no competing research group has refuted their data in a peer-review journal.
The search for other planets that can sustain life has yielded a result greater than they could have hoped for, Vogt said. It has demonstrated these planets aren’t rare — in fact, the universe is teeming with them.
“We’ve only looked at about 25 percent of the stars within the sphere of our study, [which is] about 22 lightyears,” Vogt said. “When you work out the statistics, it tells you that about one out of eight stars have these potential Earths around them. When you consider the billions of stars in our universe, it tells you there must be millions and potentially billions of planets like these.”
UCSC has been a hotspot for astronomy and astronomical discoveries since the school opened. In order to jump-start interest in UCSC, the UC system made UCSC the headquarters of Lick Observatory. UCSC was ranked No. 1 in terms of its scientific contributions and how often it has been cited in reference to other works in a 2008 paper by Anne Kinney, director of the astronomy and physics division in NASA’s Office of Space Science.
Vogt has been on the faculty of UCSC and the Lick Observatory for 34 years, and has won an impressive array of awards throughout his years of astronomy. He built the Hamilton Spectrometer at Lick in the 1980s and went on to design the Automated Planet Finder (APF), which began gathering data this year. Every clear night it can, the APF automatically looks at candidate stars and searches for planets that may be in the star’s system.
Vogt has been active in other areas of academic interest as well. On Feb. 28, the Annual Faculty Research Lecture was held at the UCSC Recital Hall. Introduced by Chancellor George Blumenthal as “the papa bear of planet exploration,” Vogt was given the honor of lecturing at this special event.
At this lecture, Vogt described his methods of research, the impact of his findings, and a method of traveling among the stars that had been proposed in the 1960s. This method of travel would enable us to see the planets themselves.
“It was called Project Orion,” Vogt said. “[The star craft] was called a nuclear propulsion space vehicle, and you would just drop nuclear warheads out the back to accelerate. In about a month you would get up to about an eighth of the speed of light.”
The goal of such a spacecraft would be to do a flyby of the planet and take pictures of the planet and surrounding celestial bodies that could be sent back to Earth. Then astronomers would be able to see what the surface and its atmosphere look like, and in turn analyze its habitability.
Jonathan Fortney, associate professor of astrophysics and astronomy at UCSC, is also involved in the search for exoplanets. Using the Hubble Space Telescope, Fortney recently helped characterize the atmosphere of a super-Earth discovered prior to Gliese 667Cc, in 2009.
“We have found the atmosphere of this planet is dominated by water vapor (steam),” Fortney said.
Called GJ1214b, this planet has an estimated surface temperature of 450 degrees Fahrenheit, according to a Hubble press release.
However, the search for exoplanets is not the only path to discovery walked by UCSC researchers. Xavier Prochaska, a UCSC astrophysicist and astronomer, seeks answers to deep questions about our place in the universe as well.
Prochaska studies clouds of primordial gas left over from the Big Bang Theory. He uses quasars to shine light behind the clouds, much like a flashlight, to study the elements within them. Quasars are remote, luminous celestial objects that emit energy.
Studies of these clouds help explain one of the theories of how the universe produced itself, called Big Bang Nucleosynthesis.
“At first there was only hydrogen — just free protons,” Prochaska said. “After the Big Bang, about seven minutes, give or take, things had cooled down enough to start making other elements — like helium, lithium and boron. It’s actually very hard to make carbon, and that only occurred after the first stars were made.”
The glass clouds Prochaska seeks are called “pristine gas.” They only contain helium and deuterium, a heavy isotope of hydrogen.
“We’re really testing … in this case, confirming, how the first elements were formed in the universe,” Prochaska said.
The current chair of UCSC’s astrophysics department, Greg Laughlin, has been a part of Vogt’s recent discoveries. Laughlin was key in creating a new program that takes raw data of light spectroscopy and analyzes it completely. This project allowed Vogt to take publicly archived HARPS Swiss data concerning the same Gliese 581 star system and combine it with his own data. This led to the discovery of the disputed super-Earth Gliese 581g.
Laughlin’s research includes the search for exoplanets, but he helps undergraduates with research of their own.
“This is a great training ground,” Laughlin said. “[Astrophysics] is a great major for learning practical skills for the modern economy. One of my students went straight from grad school to a senior data scientist at LinkedIn.”
Other students have been researching the skies as well. Matteo Crismani studies planets that have short orbital periods, which seems contrary for planets of their size. He said he believes, and is testing the idea, that inflation of these planets is due to the magnetic field of the planet or star, which creates a “toaster effect,” causing them to swell.
Even first-years like Tanmayi Sai are beginning to conduct research early in their academic career. Sai is using NASA data to hunt for Brown dwarfs, using statistical tools.
“Being proactive is what its all about,” Laughlin said. “You pay so much to come here — take advantage of your ability to be proactive. Go beyond what is expected.”
As Carl Sagan said, “We are star-stuff.” The quest to know our universe is only beginning, and UCSC astronomers and astrophysicists are at the forefront of that journey.