MOST Discoveries

Small Satellite Makes Big Discovery

The MOST microsatellite has made a major astronomical discovery. The small space telescope has revealed that the star Procyon does not oscillate. This contradicts previous  observations made from Earth-based telescopes. The discovery suggests that long-held theories on the formation and aging of the Sun and other stars need to be reconsidered.

Procyon is the eighth in importance in the night sky for its brightness. It is located in the Small Dog constellation (Canis Minor).

Procyon is the eighth in importance in the night sky for its brightness. It is located in the Small Dog constellation (Canis Minor). (Credit: Canadian Space Agency)

Image of a globular cluster of stars

A globular cluster of stars as seen by Hubble Space Telescope. (Credit: NASA, ESA, K. Sahu of STScI)

Procyon is a star in our Galaxy that is two times larger and seven times brighter than the Sun. However, the star has entered the last phase of its life and is becoming dimmer. As a result of studies conducted on the oscillation of the Sun, scientists have long believed that Procyon and other stars like it in the Milky Way emit similar pulses. MOST has proved them wrong.

Procyon's revelation

Image of Eta Bootis, or Muphrid (a solitary star in the Bootes constellation)

Eta Bootis, or Muphrid, is a solitary star in the Bootes constellation. It was used by MOST to test its instruments. (Credit: Canadian Space Agency)

Maquette de MOST

MOST Model (Credit: Canadian Space Agency)

In January and February 2004, the MOST space telescope monitored Procyon over 32 consecutive days and detected no oscillations. "Day after day, we received data. The noise was dropping, but the signal did not appear", explains MOST mission scientist Jaymie Matthews. "And then, we began to realize that nothing was going to come out. This was a surprise and shocked us all," he said. Matthews, of the University of British Columbia, compared the situation to that of a physician discovering that a patient in good health had neither a pulse nor a heartbeat. To avoid drawing the wrong conclusions, the research team checked whether MOST's scientific instruments were functioning properly. The instruments were indeed in good working order and even detected pulses from another star, Eta Bootis.

The MOST findings challenge those using models based on observations from Earth for measuring stellar oscillations. According to those models, Procyon should have vibrated and oscillated at a greater amplitude than the Sun. Astronomers have already begun to review their theories on the emission of light from the core of celestial bodies such as the Sun. A French team that was in the process of planning a space mission to study Procyon's oscillations in 2006 is modifying its project in light of MOST's discovery. Barely a year since its launch, the small Canadian telescope has already expanded the boundaries of our knowledge of space.