Twinkle, twinkle little star how I wonder what you are
These are familiar lyrics to a beloved childrens song, but today astrophysics researchers at West Virginia University are much more interested in a wobble than they are in a twinkle.
WVU Department of Physicsprofessors Maura McLaughlin and Duncan Lorimer are part of a research collaborative that recently published evidence of the possibility of a three-body pulsar system, which, if proven true, would be a first-of-its-kind discovery in the universe. The research teams initial findings have been published in Science Express, the online journal of the publication Science.
Pulsars are the rapidly spinning collapsed cores left over after a massive star ends its life as a supernova explosion. Pulsars emit beams of radio waves which sweep over the Earth with highly regular pulses of energy. There are almost 2,000 known pulsars in our galaxy. Five percent of those pulsars have short orbits of 10 milliseconds or less. The orbits of those short-period (millisecond) pulsars are generally some of the most perfect circular orbits in the universe.
The international team is led by one of McLaughlin and Lorimers former doctoral students, David Champion, who is currently based at the Australia Telescope National Facility in Sydney.
The research article,An Eccentric Binary Millisecond Pulsar in the Galactic Plane(available athttp://www.sciencemag.org/cgi/content/abstract/1157580), describes unusual findings about a newly discovered millisecond pulsar with a remarkable and decidedly noncircular orbit. Astronomers precisely measure the shape of a pulsars orbit by measuring its wobble as it moves around the common center of mass of a two-pulsar system.
Along with the new pulsars strange noncircular orbit, its also unusual that the pulsar is paired with a companion star that is similar to the sun, according to the researchers. Typically, millisecond pulsars are partnered with white dwarf stars�€what stars like the sun become after they have exhausted their nuclear fuel.
The fast spin of the pulsar and its unusual orbit pattern, coupled with its exceptional type of companion star, is completely unprecedented within the framework of current pulsar formation theories, and requires another explanation as to how it was formed, physicists say. One possibility put forward by Champion and others is that the eccentric pulsar orbit is the result of a triple-star system, where the third companion star is in a much wider orbit that is highly inclined with respect to the other two stars. The effect of a hypothetical third body would be to continuously perturb the orbit into a noncircular shape.
This discovery shows that there are still many surprises in store for astronomers studying the pulsar population,Lorimer said.Further observations of this system will test the three-body hypothesis and tell us how common this process is in millisecond pulsar formation.
The research team members are conducting an ongoing sky survey using the 1,000-foot Arecibo radio telescope in Puerto Rico. Follow-up observations of the pulsar and its companion star will use Arecibo, theRobert C. Byrd Green Bank Telescopein Green Bank, Pocahontas County; the Westerbork Synthesis Radio Telescope in the Netherlands; and the Gemini North Observatory in Hilo, Hawaii.
The new pulsar also highlights the crucial role of the Arecibo telescope in pulsar research,McLaughlin said.Without Arecibos unparalleled sensitivity, this new pulsar would have eluded discovery for many years.
McLaughlin and Lorimer have long been involved in pulsar research. In 2003, they were part of an international team that discovered the first dual-pulsar system some 2,000 light years away from Earth.
The WVU Department of Physicsin theEberly College of Arts and Sciencesprovides a complete educational environment for undergraduate and graduate students, which includes both cutting-edge research and outstanding teaching. Areas of active research include astronomy, condensed matter physics, theoretical nonlinear and fluid dynamics, theoretical high energy physics, and plasma and space physics. The department provides comprehensive undergraduate and graduate course curriculum leading to bachelors, masters and doctoral degrees.