Dark side of a failed star:
Bishop’s professor helps make astronomical discovery
Two-and-a-half thousand light-years away exist two very important celestial objects that have just been discovered. Dr. Lorne Nelson, professor and department chairperson of physics at Bishop’s University, helped find a rare binary system consisting of a failed star orbiting a dead sun.
Dr. Nelson began the story of how he wound up involved with this momentous discovery with the Kepler space telescope. The telescope has helped find thousands of planets before, said Nelson. Looking through it, members of his team, Dr. Saul Rappaport from M.I.T. and Andrew Vanderburg from Harvard noticed “an interesting signal” as they observed a faraway speck of light.
“What they saw was an eclipse,” explained Nelson. “Every 71 minutes, like clockwork, another eclipse occurred. That meant that they were looking at two objects. This is essentially where I got involved.”
The discovery of the eclipses sparked a project on an international scale. With help from places such as South America and South Africa, Dr. Nelson and his team got to work on measuring the eclipses, using computer models to study the phenomenon.
The Mont-megantic Observatory, said the professor, played a pivotal role in identifying the objects, called dwarfs due to their relatively small size. The speck of light Rappaport and Vanderburg had seen was a dead star called white dwarf. Nelson explained that the
By press time, 4,700 Hydro Quebec customers in the Townships were without power following a violent rain and wind storm that hit the region around 2:30 p.m. yesterday.
Pictured above was the culprit responsible for one of the 13 service interruptions in the area.
A tree had fallen on a power line on Broadhurst Road just off Route 143.
Hydro crews accompanied by firefighters were on the scene around 5 p.m. making a plan to clear the fallen tree and get the line back up and running as soon as possible.
The total number of customers across the province who lost power yesterday was 5,474 according to Hydro Quebec’s website.
white dwarf is the remnant of a burned-out sun. The object passing over the white dwarf, causing the eclipses, is called a brown dwarf and is an object the professor described as a half way point between being a sun and a gas planet, hence it’s other name, ‘failed star’.
“The glow coming off the white dwarf is very much like a charcoal,” illustrated Nelson, adding that even though the star died over 50 million years ago, it still generates a tremendous amount of heat and light, since “50 million years is a relatively short amount of time” in terms of space.
The two dwarfs, called a binary system, are an extremely rare and important discovery.
“We do find white dwarfs in the galaxy, it’s the most common way for suns to die. Our sun will eventually die this way,” explained Nelson. “The white dwarf is now the size of the earth, but with a huge mass. It is a million times denser than water. What is rare is to find a white dwarf in a binary, and even rarer to find with a brown dwarf.”
The significance of this, according to the professor, is that it confirms some scientific theories and inspires new ones.
“This is an extreme case of evolution that puts our physics theories to the test. We can test our models of how systems are created and how they evolve,” said Nelson. “We can develop further theories as to what may happen.”
The current theory regarding the future of the binary system is that the brown dwarf will eventually be ‘eaten’ by the white dwarf in less than 250 million years, which, Nelson mentions again, isn’t long in terms of evolution. This qualifies them as the shortest-period pre cataclysmic variable ever.
The dwarfs, he explained, are moving at tremendous speeds. “They’re almost so close together that they are touching,” he said. “When that happens, the outer layers of the brown dwarf will be cannibalized by the white dwarf. It is a stage of evolution of star prediction which will help us understand the physics behind it.”
The professor remarks that the more physics scientists can understand, the more they can understand “the big picture”, which eventually lets us know what we can expect from our own solar system and its evolution. There is, however, further scientific interest in the system.
“The next step is to measure the dark side of the brown dwarf,” said Nelson, explaining that the failed star is somewhat of a “poster child” for what he called the “hot side/cold side model”. The brown dwarf, he said, is what is called phase locked. “One side is always facing the white dwarf, like our moon, and the white dwarf is really heating up that one side. We’ve never seen the other side of the dwarf; the cold side.”
Exploring the dark side of the failed star will hopefully help explain why it is so cold, which no flow of heat, considering that the side facing the white dwarf is over 5 000 degrees Celsius, near the temperature of the surface of the sun, according to Nelson.
“It’s a mystery. The binary system is so far away that we can’t send someone over there,” he commented. “It’s tough to observe, but it’s a rare object. You wouldn’t expect it to be close anyway.”
“Light travels at a speed of 299 792 458 meters per second,” said Nelson, referring to the distance the binary system is from earth. “So you can imagine how far the dwarfs must be if it took light 2 500 years to reach it. We’re going to need bigger telescopes.”
As for how he feels about being at the center of such a huge discovery, the professor is modest:
“I’m obviously elated,” laughed Nelson. “But there are many more mysteries to be solved. I live by the saying ‘I’m only as good as what I did today’ so… I guess I have to start a new project!”