14 DAY TRIAL // An international team of astronomers, featuring experts from the United States, Canada and New Zealand, were recently able to shed more light on the origins of rare and mysterious white dwarf systems that feature a star accreting matter from a compact companion located very close by.
These systems are now named for AM Canum Venaticorum (AM Cvn), a weird binary system that was discovered at the middle of the twentieth century. At first, sky watchers thought it was a single star, but more advanced equipment determined it was in fact a binary system.
The main trait of the system was that the objects were very close to each other, completing an orbit around their common center of gravity in just 18 minutes. By comparison, the innermost planet in our system, Mercury, completes an orbit around the Sun in 88 days. Earth needs 365 days to do the same.
Over time, the name AM CVn ended up being used for all binary systems with close-orbiting stars where one member of the pair accumulates matter from the other. The latter is usually a compact star such as a white dwarf, the helium-burning remnant of a main-sequence star that weighed up to 8 solar masses.
Over the last 50 years, astronomers have been puzzling as to the origins of AM CVn systems. The new study, published in a recent issue of the journal Monthly Notices of the Royal Astronomical Society Letters, and available online on the arXiv server, proposes two candidates that will become AM CVn.
The study was led by experts with the University of Oklahoma in Norman, the University of Texas in Austin, the Smithsonian Astrophysical Observatory, the University of Alberta in Edmonton, Columbia University in New York, and Victoria University, in New Zealand.
Using the X-ray capabilities of the NASA Chandra X-ray Observatory (CXO) and the European Space Agency's (ESA) XMM-Newton telescope, the team was able to find two binary systems – J0751 and J1741 – that have the potential to turn into AM CVn later on.
The study also included optical wavelength images collected by the 2.1-meter (6.9-foot) telescope at McDonald Observatory, in Texas, and the 1-meter (3.28-foot) telescopes at Mt. John Observatory, in New Zealand. The illustration attached to this article shows the potential paths they may take to become AM CVn systems.
One of the reasons why this weird type of binary systems is so important for astronomers is that they are hypothesized to produce gravitational waves, which are distortions in spacetime that arise from Albert Einstein's theory on general relativity. Detecting these variations has thus far proven elusive.