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Canada’s first space telescope.
New observations of Procyon from MOST, Canada's space telescope, have called long-held assumptions about the star into doubt. Launched a year ago, MOST watched Procyon 8-times a minute, making a total of 250,000 observations over the course of 32 days. It found that the star is completely stable, and doesn't pulsate or vibrate in any way. This challenges 20 years of speculation that Procyon does vibrate, and could reveal insights about its interior - Astronomers will need to find a new candidate.
MOST, Canada’s first space telescope, celebrates its first birthday today, but its latest surprising results could spoil the party for other Astronomers whose earlier results are now being questioned.
The MOST team used their tiny but powerful satellite as a stellar stethoscope to take the pulse of one of the best-known stars in the Galaxy, called Procyon (PRO-see-yon), and were shocked to discover their cosmic patient is a "flat liner". The star shows none of the pulsations predicted by over 20 years of earlier theory and observations from Earth. The journal nature will publish these unexpected findings on July 1.
"The lack of a pulse doesn't mean the star Procyon is dead," explained MOST Mission Scientist Dr. Jaymie Matthews of the University of British Columbia. "But it does mean that some of our long-held theories about stars like this need to be put on the critical list. And that future space missions following in the path of MOST will have to revise their target lists and observing strategies in light of this null result."
MOST, which stands for Microvariability and Oscillations of STars, is a Canadian Space Agency mission. UBC is the main contractor for the instrument and scientific operations of the MOST mission.
MOST is not much bigger than a suitcase but is able to measure the brightness variations of stars more precisely than any other instrument on Earth or in space. It was launched one year ago on June 30, aboard a modified Russian nuclear missile. To mark the occasion, MOST scientists celebrated with a birthday party complete with cake and dehydrated "space" ice cream.
"MOST is only one year old, but it’s proving to be a very precocious child," said Roger Colley, a senior official from the Canadian Space Agency. "In its first six months of operation, MOST has already given us new perspectives on the stars we thought we knew best, the ones in our own Galactic backyard. In that way, it’s providing new insights into the Sun, the star we need to understand better to predict the future of our home planet."
The MOST Canadian space telescope was launched from northern Russia, in June 2003, aboard a former Soviet ICBM (Intercontinental Ballistic Missile) converted to peaceful use. Weighing only 54 kg, this suitcase-sized microsatellite is packed with a small telescope and electronic camera to study stellar variability.
Its first prime target was Procyon, the eighth brightest star in the night sky, similar to the Sun but more massive and further along in life. Astronomers had concluded that Procyon was the best candidate for the new technique of "asteroseismology" – using surface vibrations to probe the inside of a star, similar to how geophysicists use earthquake vibrations to probe the Earth's core.
MOST monitored Procyon up to eight times per minute for 32 days, with lapses totalling only seven hours over that entire time. Accumulating about 250,000 individual measurements, MOST reached a level of light-measuring precision at least 10 times better than the best ever achieved before from Earth or space. The MOST team was surprised to find that Procyon was not vibrating, and soon showed that a more careful treatment of stellar models indicated that it should indeed be stable.
The lack of waves detected on the surface of Procyon has ironically generated waves in the worldwide community of stellar astronomers. These results contradict theories and observational evidence that had mounted over the last 20 years. Several planned international space missions have been designed based on the firm belief that stars like Procyon pulsate. The MOST findings mean target lists and observing strategies for these satellites may have to be seriously revamped.
Future targets for MOST include other stars representing the Sun at various stages in its life, and stars known to have giant planets. MOST is designed to be able to register the tiny changes in brightness that will occur as a planet orbits its parent star. The way in which the light changes will tell Astronomers about the atmospheric composition of these mysterious worlds, and even if they have clouds.
"It’s like doing a weather report for a planet outside our Solar System," says Dr. Jaymie Matthews, MOST Mission Scientist, of the University of British Columbia.
MOST (Microvariability & Oscillations of STars) is a Canadian Space Agency mission. UBC is the main contractor for the instrument and scientific operations of the MOST mission.
Dynacon Inc. of Mississauga, Ontario, is the prime contractor for the satellite and its operation, with the University of Toronto Institute for Aerospace Studies (UTIAS) as a major subcontractor.
MOST is tracked and operated through a global network of ground stations located at UTIAS, UBC and the University of Vienna.
Other partners include the Harvard-Smithsonian Center for Astrophysics, Université de Montréal, and St. Mary’s University in Halifax.
For more information on MOST, visit: www.astro.ubc.ca/MOST/
For more information on the Canadian Space Agency, visit: www.space.gc.ca/asc/eng/default.asp
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