Scorpius X-1, uncovered

03/03/2015

Scorpius X-1 was the first X-ray source discovered outside the Solar System and is the prototypical X-ray binary, the brightest in the sky with persistent X-ray emission. However, more than 50 years after its discovery, its dynamical parameters remained unknown. A recent study led by Daniel Mata Sánchez, PhD student La Caixa-SO at the IAC, with the participation of other IAC/ULL researchers, has obtained new dynamical constraints to the masses of its components, combining statistical analysis of previous orbital data with the best near-infrared spectrum of the source to date. The results indicate that the system is composed of a neutron star with less than 1.73 M⊙, plus a companion star with a mass between 0.28 and 0.70 M⊙, spectral type later than K4 and luminosity class IV. The work has been published in Monthly Notices Letters of the Royal Astronomical Society.