https://phys.org/news/2018-05-massive-neutron-stars.html

Researchers from the Universitat Politècnica de Catalunya (UPC) and the Canary Islands Institute of Astrophysics (IAC) used an innovative method to measure the mass of one of the heaviest neutron stars known to date. Discovered in 2011 and called PSR J2215+5135, with about 2.3 solar masses it is one of the most massive of the more than 2,000 neutron stars known to date. Although a study published in 2011 reported evidence of a neutron star with 2.4 solar masses, the most massive neutron stars that had previously achieved a consensus among scientists, reported in 2010 and 2013, have 2 solar masses.

The study was led by Manuel Linares, Marie-Curie researcher of the Astronomy and Astrophysics Group (GAA), linked to the UPC's Department of Physics, in collaboration with the astronomers Tariq Shahbaz and Jorge Casares of the IAC. The researchers used data obtained from the Gran Telescopio Canarias (GTC), the largest optical and infrared telescope in the world, the William Herschel Telescope (WHT), the Isaac Newton Telescope Group (ING) and the IAC-80 telescope, in combination with dynamical models of binary stars with irradiation. An article reporting on the results of the study, entitled "Peering into the dark side: magnesium lines establish a massive neutron star in PSR J2215+5135", was published in the Astrophysical Journal.