For immediate release (January 13, 2003, Ottawa, ON) -
A team of astronomers led by JJ. Kavelaars of the National Research Council of Canada (NRC) and Matthew Holman of the Harvard-Smithsonian Center for Astrophysics has discovered three previously unknown moons of Neptune. This boosts the number of known satellites of the gas giant to eleven. These moons are the first to be discovered orbiting Neptune since the Voyager II flyby in 1989, and the first discovered from a ground-based telescope since 1949.
It now appears that the giant planet's irregular satellite population is the result of an ancient collision between a former moon and a passing comet or asteroid. "These collisions result in the ejection of parts of the original parent moon and the production of families of satellites," said Dr.Kavelaars. "Those families are exactly what we're finding."
The team that discovered these new satellites of Neptune includes Holman and Kavelaars, graduate student Tommy Grav of the University of Oslo & Harvard-Smithsonian Center for Astrophysics, and undergraduate students Wesley Fraser and Dan Milisavljevic of McMaster University, Hamilton, Ontario, Canada.
The new satellites were a challenge to detect because they are only about 30-40 kilometers in size. Their small size and distance from the Sun prevent the satellites from shining any brighter than 25th magnitude, about 100 million times fainter than can be seen with the unaided eye.
To locate these new moons, Holman and Kavelaars employed an innovative technique. Using the 4.0-meter Blanco telescope at the Cerro Tololo Inter-American Observatory, Chile, and the 3.6-meter Canada-France-Hawaii Telescope, Hawaii, they took multiple exposures of the sky surrounding the planet Neptune. After digitally tracking the motion of the planet as it moved across the sky, they then added many frames together to boost the signal of any faint objects. Since they tracked the planet's motion, stars showed up in the final combined image as streaks of light, while the moons accompanying the planet appeared as points of light.
"These discoveries required painstakingly careful observations, and will figure prominently when astronomy textbooks are revised," said Dr. Arthur Carty, NRC President. "They are exemplary of the international efforts that underpin so many advances in modern astronomy."
Based in La Serena, Chile, the Cerro Tololo Inter-American Observatory is part of the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation.
The Canada-France-Hawaii Telescope is operated by a joint agreement between the National Research Council of Canada, the Centre National de la Recherche Scientifique of France, and the University of Hawaii.
Recognized globally for research and innovation, Canada's National Research Council (NRC) is a leader in the development of an innovative, knowledge-based economy for Canada through science and technology.
For more information, please visit the NRC Web site at
Herzberg Institute of Astrophysics
National Research Council Canada
Tel: (613) 998-7352
Dr. JJ Kavelaars
National Research Council Canada
Tel: (250) 363-8694
The researchers are currently conducting follow-up observations to better define the orbits of the newfound moons using orbital predictions supplied by Brian Marsden (Director of the Minor Planet Center in Cambridge, Mass.) and Robert Jacobson (Jet Propulsion Laboratory).
Team members, Brett Gladman (University of British Columbia, Canada), Jean-Marc Petit, Philippe Rousselot, and Olivier Mousis (Observatoire de Besancon, France) and, Philip Nicholson and Valerio Carruba (Cornell University) conducted additional observations using the Hale 5-m telescope on Mount Palomar and the European VLT in Chile. Additional tracking observations were also made using the Nordic Optical Telescope on La Palma, Spain.