%0 Journal Article
%T Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger
%+ Laboratoire Univers et Particules de Montpellier (LUPM)
%+ Astrophysique Relativiste Théories Expériences Métrologie Instrumentation Signaux (ARTEMIS)
%+ AstroParticule et Cosmologie (APC (UMR_7164))
%+ Galaxies, Etoiles, Physique, Instrumentation (GEPI)
%A Pian, E.
%A d'Avanzo, P.
%A Benetti, S.
%A Branchesi, M.
%A Brocato, E.
%A Campana, S.
%A Cappellaro, E.
%A Covino, S.
%A d'Elia, V.
%A Fynbo, J.P.U.
%A Getman, F.
%A Ghirlanda, G.
%A Ghisellini, G.
%A Grado, A.
%A Greco, G.
%A Hjorth, J.
%A Kouveliotou, C.
%A Levan, A.
%A Limatola, L.
%A Malesani, D.
%A Mazzali, P.A.
%A Melandri, A.
%A Møller, P.
%A Nicastro, L.
%A Palazzi, E.
%A Piranomonte, S.
%A Rossi, A.
%A Salafia, O.S.
%A Selsing, J.
%A Stratta, G.
%A Tanaka, M.
%A Tanvir, N.R.
%A Tomasella, L.
%A Watson, D.
%A Yang, S.
%A Amati, L.
%A Antonelli, L.A.
%A Ascenzi, S.
%A Bernardini, M.G.
%A Boër, M.
%A Bufano, F.
%A Bulgarelli, A.
%A Capaccioli, M.
%A Casella, P.G.
%A Castro-Tirado, A.J.
%A Chassande-Mottin, E.
%A Ciolfi, R.
%A Copperwheat, C.M.
%A Dadina, M.
%A de Cesare, G.
%A Di Paola, A.
%A Fan, Y.Z.
%A Gendre, B.
%A Giuffrida, G.
%A Giunta, A.
%A Hunt, L.K.
%A Israel, G.
%A Jin, Z.-P.
%A Kasliwal, M.
%A Klose, S.
%A Lisi, M.
%A Longo, F.
%A Maiorano, E.
%A Mapelli, M.
%A Masetti, N.
%A Nava, L.
%A Patricelli, B.
%A Perley, D.
%A Pescalli, A.
%A Piran, T.
%A Possenti, A.
%A Pulone, L.
%A Razzano, M.
%A Salvaterra, R.
%A Schipani, P.
%A Spera, M.
%A Stamerra, A.
%A Stella, L.
%A Tagliaferri, G.
%A Testa, V.
%A Troja, E.
%A Turatto, M.
%A Vergani, S.D.
%A Vergani, D.
%< avec comité de lecture
%@ 0028-0836
%J Nature
%I Nature Publishing Group
%V 551
%P 67-70
%8 2017
%D 2017
%Z 1710.05858
%R 10.1038/nature24298
%K gamma ray: burst
%K mass: solar
%K n: capture
%K spectral
%K gravitational radiation
%K nucleosynthesis
%K neutron star
%K observatory
%K ultraviolet
%K platinum
%K velocity
%K optical
%K opacity
%K galaxy
%K gold
%K absorption
%Z Physics [physics]/Astrophysics [astro-ph]Journal articles
%X The merger of two neutron stars is predicted to give rise to three major detectable phenomena: a short burst of gamma-rays, a gravitational wave signal, and a transient optical/near-infrared source powered by the synthesis of large amounts of very heavy elements via rapid neutron capture (the r-process). Such transients, named "macronovae" or "kilonovae", are believed to be centres of production of rare elements such as gold and platinum. The most compelling evidence so far for a kilonova was a very faint near-infrared rebrightening in the afterglow of a short gamma-ray burst at z = 0.356, although findings indicating bluer events have been reported. Here we report the spectral identification and describe the physical properties of a bright kilonova associated with the gravitational wave source GW 170817 and gamma-ray burst GRB 170817A associated with a galaxy at a distance of 40 Mpc from Earth. Using a series of spectra from ground-based observatories covering the wavelength range from the ultraviolet to the near-infrared, we find that the kilonova is characterized by rapidly expanding ejecta with spectral features similar to those predicted by current models. The ejecta is optically thick early on, with a velocity of about 0.2 times light speed, and reaches a radius of about 50 astronomical units in only 1.5 days. As the ejecta expands, broad absorption-like lines appear on the spectral continuum indicating atomic species produced by nucleosynthesis that occurs in the post-merger fast-moving dynamical ejecta and in two slower (0.05 times light speed) wind regions. Comparison with spectral models suggests that the merger ejected 0.03-0.05 solar masses of material, including high-opacity lanthanides.
%G English
%2 https://hal.science/hal-01645878/document
%2 https://hal.science/hal-01645878/file/Pia.pdf
%L hal-01645878
%U https://hal.science/hal-01645878
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