Unresolved stellar companions with Gaia

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• Vasily Belokurov University of Cambridge
• Wednesday 24 March 2021, 14:00-15:00
• online .

If you have a question about this talk, please contact Nicola Giacobbo.

PhD meet & greet at 12.30

For stars with unresolved companions, motions of the centre of light and that of mass decouple, causing a single-source astrometric model to perform poorly. We show that such stars can be easily detected using the information provided by Gaia. Using the astrometric wobble technique applied to the Gaia DR2 data we show how the binary fraction evolves across the Hertzsprung–Russell diagram. The observed incidence of unresolved companions is high for massive young stars and drops steadily with stellar mass, reaching its lowest levels for white dwarfs. We highlight the elevated binary fraction for the nearby blue stragglers and blue horizontal branch stars. We also illustrate how unresolved hierarchical triples inflate the relative velocity signal in wide binaries. Finally, we point out a hint of evidence for the existence of additional companions to the hosts of extrasolar hot Jupiters.

This talk is part of the Astrophysics Talks Series series.

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• Astrophysics Talks Series
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