Detalles de publicación
PP 023083
The orbital period, black hole mass and distance to the X-ray transient GRS 1716-249 (=N Oph 93)
(1) Instituto de Astrofisica de Canarias, 38205 La Laguna, Tenerife, Spain
(2) Departamento de Astrofisica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
(3) Cerro Tololo Inter-American Observatory, NSF’s National Optical-Infrared Astronomy Research Laboratory, Casilla 603, La Serena, Chile
(4) Department of Physics, Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
(5) Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
(6) Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands
(7) SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands
(8) School of Physics, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
We present evidence for a 0.278(8) d (=6.7 h) orbital period in the X-ray transient GRS 1716-249 (=N Oph 93), based on a superhump modulation detected during the 1995 mini-outburst plus ellipsoidal variability in quiescence. With a quiescent magnitude of r=23.19+-0.15 N Oph 93 is too faint to warrant a full dynamical study through dedicated time-resolved spectroscopy. Instead, we apply the FWHM-K2 correlation to the disc Halpha emission line detected in Gran Telescopio Canarias spectra and obtain K2=521+-52 km/s. This leads to a mass function f(M)=4.1+-1.2 Msun, thus indicating the presence of a black hole in this historic X-ray transient. Furthermore, from the depth of the Halpha trough and the quiescent light curve we constrain the binary inclination to i=61+-15 deg, while the detection of superhumps sets an upper limit to the donor to compact star mass ratio q=M2/M1<=0.25. Our de-reddened (r-i) colour is consistent with a ~K6 main sequence star that fills its Roche lobe in a 0.278 d orbit. Using all this information we derive a compact object mass M1=6.4+3.2-2.0 Msun at 68 per cent confidence. We also constrain the distance to GRS 1716-249 to 6.9+-1.1 kpc, placing the binary ~0.8 kpc above the Galactic Plane, in support of a large natal kick.