In May and September 1996, we observed Cygnus X-3 with FSpec at the MMT in the infrared H- & K-bands at unprecedented resolution. We obtained a K-band spectrum on 10 consecutive days, as well as two sets of spectra covering a full 4.8 hr orbit, four months apart. We have identified a number of phenomena in these spectra. The He II lines are broad and WR like, the He I features are much narrower and the 2p-2s 2.058 mu m feature can flip from emission to absorption on a timescale of an hour, not clearly correlated with orbital phase. We confirm the Doppler-shifting of the He lines with orbital phase at both greater spectral- and phase-resolution than previous studies, allowing an orbital solution to be produced. Our H-band spectrum confirms the Hydrogen-deficiency of the system. Finally, we discover a previously undetectable (due to poorer spectral resolution) absorption feature at 2.13 mu m which, unlike any other lines in the system, stays constant in strength and wavelength (does not shift with orbit). We have not confidently identified this feature, however since it is clearly not a common interstellar line, it must be associated with Cyg X-3, and may trace extended material in the system. The suggested nature of the Cyg X-3 system, namely a WR + compact object, may be drawn into question given these new spectroscopic data.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1996