The Spectrum of SS 433 in the H and K Bands

• Published in: arXiv.org
• Main Authors: Robinson, E L, Froning, C S, Jaffe, D T, Kaplan, K F, Kim, H, Mace, G N, Sokal, K R, J -J Lee
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 26.04.2017
• Subjects: Accretion disks; Distortion; Emission; Helium; Outflow; Physics - High Energy Astrophysical Phenomena; Physics - Solar and Stellar Astrophysics; Radial velocity; Spectrograms; Stellar winds; X ray binaries; X ray stars
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1704.08166

SS~433 is an X-ray binary and the source of sub-relativistic, precessing, baryonic jets. We present high-resolution spectrograms of SS 433 in the infrared H and K bands. The spectrum is dominated by hydrogen and helium emission lines. The precession phase of the emission lines from the jet continues to be described by a constant period, P_jet= 162.375 d. The limit on any secularly changing period is \(|\dot P| \lesssim 10^{-5}\). The He I 2.0587 micron line has complex and variable P Cygni absorption features produced by an inhomogeneous wind with a maximum outflow velocity near 900 km/s. The He II emission lines in the spectrum also arise in this wind. The higher members of the hydrogen Brackett lines show a double-peaked profile with symmetric wings extending more than +/-1500 km/s from the line center. The lines display radial velocity variations in phase with the radial velocity variation expected of the compact star, and they show a distortion during disk eclipse that we interpret as a rotational distortion. We fit the line profiles with a model in which the emission comes from the surface of a symmetric, Keplerian accretion disk around the compact object. The outer edge of the disk has velocities that vary from 110 to 190 km/s. These comparatively low velocities place an important constraint on the mass of the compact star: Its mass must be less than 2.2 M_solar and is probably less than 1.6 M_solar.