astronomy

From Hawaii to the dark corners of space

telescopes

The Subaru Telescope, whose name is the Japanese word for the Pleiades star cluster, is located on an isolated Hawaiian peak that protrudes above most of the Earth's weather, making the site one of the best on Earth for astronomical observing.

PRINCETON (US)—The isolated peak of Mauna Kea, a dormant volcano in Hawaii, is home-base for a team of international scientists with sights set on deep space.

The researchers from Princeton University and the National Astronomical Observatory of Japan (NAOJ) have agreed to collaborate over the next 10 years, using the Subaru Telescope, one of the largest in the world, to gaze into hidden corners of the nearby universe and ferret out secrets from its distant past.

Scientists also will use the telescope to survey the distant universe, studying the physical nature of galaxies and seeking to better understand the structure of the universe, including hypothesized dark energy.

The partnership, called the NAOJ-Princeton Astrophysics Collaboration or N-PAC, will support a variety of long-term research projects. Through N-PAC, scientists will be looking for planets, hidden in the glare of the star they orbit. Finding these planets is a crucial step in answering the age-old question of the existence of extraterrestrial life. They also will be scouring the distant universe to discern the properties of the hypothesized substance known as dark energy. And they will be studying how galaxies form and change over time to learn how galaxies developed the properties observed in the present-day universe.

“I am very much excited that the collaboration between the NAOJ and Princeton University has come to this commemorative point,” says Masahiko Hayashi, director of the Subaru Telescope. “I am looking forward to seeing how both of us can together advance our knowledge on the most exciting subjects of current astronomy: extrasolar planets and cosmology.”

The studies will be made possible by a new generation of instruments specially made for the telescope. They will include the Hyper Suprime-Cam or HSC, a digital camera that captures deep images of large swaths of the sky, and the High Contrast Coronagraphic Imager with Adaptive Optics or HiCIAO, an instrument designed to detect faint objects near a bright star by masking its far more intense light. The HSC development team is led by Professors Hiroshi Karoji and Satoshi Miyazaki, and the HiCIAO team by Professor Motohide Tamura, all of NAOJ.

Together, the Japanese and Princeton astronomers plan to carry out major surveys with the telescope and its new instruments, using up to several hundred nights of telescope time.

“This is an unprecedented opportunity to pool our resources and our expertise with our Japanese colleagues,” says Edwin Turner, a professor of astrophysical sciences at Princeton. Turner is a lead scientist in an extensive new search for planets orbiting nearby stars, one of the two major projects of the collaboration. “A larger scientific context of our efforts is the search for life in the universe,” Turner adds. “Life, as we know it, requires planets to evolve, so understanding the nature of planets allows us to better estimate how many could harbor life.”

Princeton has played a leading role in some of the most important cosmology surveys of recent years, including the Wilkinson Microwave Anisotropy Probe and the Sloan Digital Sky Survey. These have given scientists profound insights into the early and current-day universe, respectively. The new effort will allow scientists to fill in the middle of the story, studying the vast periods in between by probing galaxies at distances representing those eras.

“Because of the finite speed of light, we see distant galaxies as they were in the past, thus our telescopes are time machines,” says Michael Strauss, a professor of astrophysical sciences at Princeton who is leading the Princeton team on the collaboration’s other major mission. “Einstein’s Theory of General Relativity predicts that the shapes of distant galaxies will be systematically distorted by the structures along the line of sight. Studying these distortions in the HSC data will allow the Princeton and Japanese astronomers to deduce the properties of dark energy.”

Scientists in the collaboration are also expecting surprises in the data. “If we design these surveys well, it should allow scientific discoveries that we haven’t anticipated,” Strauss says. “What will be really fun and exciting is all the other science that will come for free.”

Princeton University news: www.princeton.edu/main/news

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