* Astronomy

Title: The mass and the radius of the neutron star in the transient low mass X-ray binary SAX J1748.9-2021
Authors: Tolga Guver, Feryal Ozel

We use time resolved spectroscopy of thermonuclear X-ray bursts observed from SAX J1748.9-2021 to infer the mass and the radius of the neutron star in the binary. Four X-ray bursts observed from the source with RXTE enable us to measure the angular size and the Eddington limit on the neutron star surface. Combined with a distance measurement to the globular cluster NGC 6440, in which SAX J1748.9-2021 resides, we obtain two solutions for the neutron star radius and mass, R = 8.18 ±1.62 km and M = 1.78 ±0.3 solar masses or R = 10.93 ±2.09 km and M = 1.33 ±0.33 solar masses.

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