MARVELS of the Stars
A University of Florida-led sky survey that may double the number of known planets outside the Solar System is part of a major new survey program announced at the American Astronomical Society’s annual meeting in Austin, Texas. The Sloan Digital Sky Survey III, slated to begin mid-year and end in mid-2014, consists of four independent surveys operated by the survey’s consortium.
One will probe the distant universe and seek to learn more about mysterious dark energy, while two of the surveys will map the Milky Way and examine origins of stars. The UF-led survey will seek to find giant planets orbiting nearby stars and uncover more about the conditions in which they form. Increasing our knowledge of how and where extrasolar planets form can help astronomers estimate the number of potentially habitable environments for life beyond our Solar System.
"What we’re undertaking here is the largest homogeneous survey of planets ever conducted," said Jian Ge, a UF professor of astronomy and the project’s principal investigator. "We not only want to find more planets, we also want to try to understand the big picture of how and where they form and evolve over time."
At the heart of the survey – known as MARVELS, short for Multi-object Apache Point Observatory Radial Velocity Exoplanet Large-area Survey – is a University of Florida (UF)-designed and built instrument capable of simultaneously surveying as many as 120 stars for planets.
The plan is to use the instrument, which employs a specially designed interferometer, to scour some 11,000 stars for orbiting giant planets – more than three times the number of stars searched by all other telescopes to date. The instrument detects planet signals through measuring the gravitational pull of the planet on the star.
The search is expected to yield not only at least 150 planets, almost double today’s number, but also provide much better understanding of the conditions needed for planets to be present. That’s important for future planet searches, including searches for Earth-like planets, because it will help astronomers narrow their search among millions of stars for those most likely to yield fast or interesting results.
"Only through a systematic, homogeneous survey like this one can we begin to understand different planet populations and probe planet distributions among different type stars and environments," Ge said. "Also, this survey will provide many signposts for other astronomers using the really big, really expensive telescopes to discover smaller mass planets, possibly Earth-like planets, and also find more systems like our Solar System."
In order to substantially boost the survey speed and sample over current planet surveys capable of single object observations, the MARVELS survey will simultaneously target 120 relatively faint stars. The faintness of the stars largely limits the survey’s sensitivity to giant planets, although the instrument has four times the light particle, or photon, collecting power than current single object planet hunting instruments at other telescopes.
The search is expected to begin in the fall, shortly after the instrument is completed and installed. Like the other surveys, the MARVELS survey will be conducted from the 2.5 meter SDSS telescope at Apache Point Observatory in New Mexico.
The Sloan Digital Sky Survey III is a continuation of two previous SDSS surveys in the past eight years. The new survey is expected to be funded in part with a $7 million grant from the Alfred P. Sloan Foundation, with the survey and its four component surveys representing a total investment of about $50 million.
The MARVELS instrument has about $2.5 million in funding, including part of an $875,000 grant from the W.M. Keck Foundation for an earlier, prototype version called the W.M. Keck Exoplanet Tracker. The University of Florida survey is also being funded by the National Science Foundation, NASA and UF. Once the instrument is up and running, UF is expected to receive an additional roughly $6 million in funding for building another survey instrument, operating the survey, and handling the survey data, Ge said.
Ge said an added benefit of UF’s participation in the project is that it will allow UF astronomers free and timely access to data from all of the surveys. "We have full access to all that data, which is a huge scientific resource," he said.
Stan Dermott, chairman of the UF astronomy department, noted that UF is also a partner with Spain in the world’s largest telescope, the Gran Telescopio Canarias, expected to begin scientific observations this year.
"Over the next 10 years," he said, "the combination of the SDSS telescope and the GTC telescope may offer UF a unique tool to investigate both giant and Earth-like planets."