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The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry
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A Be-type star with a black-hole companion
J Casares1, I Negueruela2, M Ribó3
11] Instituto de Astrofísica de Canarias, E-38205 La Laguna, Santa Cruz de Tenerife, Spain [2] Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Santa Cruz de Tenerife, Spain.
Nature
|January 17, 2014
Summary
Astronomers discovered a black hole companion to a Be star, MWC 656, using orbital disk line observations. This finding suggests black hole-Be star binaries are hard to detect via X-ray surveys.
Area of Science:
- Astrophysics
- Stellar Evolution
- X-ray Astronomy
Background:
- Stellar-mass black holes are typically found via X-ray emission from accreting gas in binary systems.
- Binary evolution models predict black holes accreting from Be stars, but only neutron stars have been observed as companions.
- Previous claims of a black hole companion to Be star MWC 656 were based on limited data.
Purpose of the Study:
- To confirm the presence and mass of a black hole companion to the Be star MWC 656.
- To investigate the accretion properties and detectability of black hole-Be star binaries.
Main Methods:
- Observed an accretion disk line mirroring the orbit of MWC 656.
- Obtained an improved radial velocity curve of the Be star by fitting Fe II profiles.
- Refined the spectral classification of the Be star.
Main Results:
- Confirmed a black hole companion of 3.8 to 6.9 solar masses orbiting MWC 656.
- The black hole is X-ray quiescent, accreting via a radiatively inefficient flow.
- The system's low X-ray luminosity makes it difficult to detect in standard surveys.
Conclusions:
- The study provides strong evidence for a black hole companion in the Be star system MWC 656.
- Black hole-Be star binaries are likely more common than previously thought but are challenging to detect.
- Future searches should consider alternative detection methods beyond X-ray surveys.
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