2014MNRAS.442.1956L

We present high-resolution spectra of the symbiotic star V1016 Cygni obtained with the Bohyunsan Optical Echelle Spectrograph in 2003 and 2005, from which we find a broad emission feature at 4881 Å. We propose that this broad feature is formed from Raman scattering of Nevii λ973 by atomic hydrogen. Thus far, the detection of Raman-scattered lines by atomic hydrogen is limited to Ovi λλ1032, 1038 and Heii λλ940, 972 and 1025. With the adoption of a centre wavelength 973.302 Å for Nevii λ973 and considering an air refractive index nair = 1.000279348, the atomic line centre of the Raman-scattered Nevii feature is determined to be 4880.53 Å. The total cross-section at the line centre of Nevii λ973 is computed to be 2.62x10^–22 cm2, with a branching ratio of 0.17. We perform Monte Carlo simulations to fit the Raman-scattered Nevii λ973. Assuming that the Nevii and Heii emission regions share the same kinematics with respect to the neutral scattering region, we find that the Raman-scattered Heii λ972 at 4850 Å and Nevii λ973 at 4881 Å are excellently fitted. We also propose that the Heii and Nevii emission regions were stationary with respect to the Hi region in 2003, but that they were receding from it with a velocity ∼ 20 km/s in 2005.