Dr. Lorne Nelson of the Bishop’s University Physics & Astronomy Department explores questions related to exotic astronomical objects, with the ultimate goal of discovering the hidden principles that govern nature. Dr. Nelson believes that scholarly research improves the human condition like no other human endeavour. He has pioneered research on brown dwarfs, which explain the relationship between stars and planets and has discovered binary systems whose properties were once only theorized. His research focuses on interacting binary stars containing compact objects such as neutron stars, black holes, and brown dwarfs, as well as how theoretical physics can be applied to astronomy.
In 2020 he was part of the first team to discover an intact planet orbiting a dead star known as a white dwarf. Long hypothesized, the discovery of a planet orbiting a white dwarf was a special find among the thousands of exoplanets that have now been discovered orbiting ordinary stars. One of the outstanding mysteries concerns the survivability of planets once their host star engulfs them and enters its final red giant phase of evolution. Are the inner planets destroyed? How massive does a planet have to be to completely expel the red giant’s gaseous envelope, thereby exposing the white dwarf in its core? These are questions that are actively being addressed by Dr. Nelson and other scientists from around the world.
This discovery was published in Nature, considered to be the world’s premier scientific journal. Dr. Nelson’s primary contributions were based on calculations that showed the object orbiting the white dwarf was most likely a giant gas planet, as opposed to another celestial object such as a red or brown dwarf. The remarkable discovery also helps us better understand the future of our own solar system and what might happen to planets such as Jupiter or Saturn when our Sun expands.
This is Dr. Nelson’s second publication in Nature, the first of which was published in 1985 and provided the scientific community with detailed calculations on the evolution of a then-new class of celestial objects known as brown dwarfs. These objects bridge the gap between gas giants and stars. As Dr. Nelson explains:
“The Sun and Jupiter are both composed of hydrogen-rich gas, but the key difference is that the Sun is 1000 times more massive. Now imagine the following thought experiment: suppose that I keep removing mass from the Sun and add it to Jupiter. When does the planet become a star? Or when does the star become a planet? It turns out that a class of ‘failed stars’ known as brown dwarfs is needed to fill in the gap between low-mass stars and giant gas planets”.
It took an additional 10 years after this seminal paper was published before the first bona fide brown dwarf was finally observed.
Dr. Nelson’s work has been published in Nature, The Astrophysical Journal, The Monthly Notices of the Royal Astronomical Society, The Physical Review, and The Journal of Cosmology & Astroparticle Physics. He has been a guest on the national science program Quirks & Quarks and has given many interviews on astronomically related discoveries. He has been a faculty member since 1988.