Notre Dame U. A one-of-a-kind star found to change over decades
Posted: Sat Sep 16, 2017 5:35 pm
2017 August 10Notre Dame U. A one-of-a-kind star found to change over decades
September 12, 2017
http://news.nd.edu/news/a-one-of-a-kind ... r-decades/
Astronomers studying the unique binary star system AR Scorpii have discovered the brightness of the system has changed over the past decade. The new evidence lends support to an existing theory of how the unusual star emits energy. AR Scorpii consists of a rapidly spinning, magnetized white dwarf star that mysteriously interacts with its companion star. The system was recently found to more than double in brightness on timescales of minutes and hours, but research recently published in The Astrophysical Journal Letters found variability on a timescale of decades.
Researchers at the University of Notre Dame analyzed data on the unique system from the Kepler Space Telescope’s K2 mission taken in 2014 before the star was known to be unusual. The data was then compared with archival sky survey images going back to 2004 to look for long-term changes in the light curve of AR Scorpii. The binary’s light curve is unique, in that it exhibits a spike in emission every two minutes as well as a major brightness variation over the approximately 3.5-hour orbital period of the two stars.
“One model of this system predicts long-term variations in the way the two stars interact. It was not known what the time scale of these changes might be — whether 20 to 200 years. By looking at the K2 and archival data, we were able to show that in addition to hourly changes in the system, there are variations occurring over decades,” said Peter Garnavich, professor and department chair of astrophysics and cosmology physics at Notre Dame.
Long-term Photometric Variations in the Candidate White-dwarf Pulsar AR Scorpii from K2, CRTS, and ASAS-SN Observations
Colin Littlefield, Peter Garnavich et al.
http://iopscience.iop.org/article/10.38 ... a8300/meta
https://arxiv.org/abs/1707.09395