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arXiv · 2112.09689

Observational identification of a sample of likely recent Common-Envelope Events

Theo Khouri·Wouter Vlemmings·Daniel Tafoya·Andrés F. Pérez-Sánchez·Carmen Sánchez Contreras·José F. Gómez·Hiroshi Imai·Raghvendra Sahai
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Abstract

One of the most poorly understood stellar evolutionary paths is that of binary systems undergoing common-envelope evolution, when the envelope of a giant star engulfs the orbit of a companion. Although this interaction leads to a great variety of astrophysical systems, direct empirical studies are difficult because few objects experiencing common-envelope evolution are known. We present ALMA observations towards sources known as water fountains that reveal they had low initial masses ($<4~{\rm M}_\odot$) and ejected a significant fraction of it over less than a few hundred years. The only mechanism able to explain such rapid mass ejection is common-envelope evolution. Our calculations show that the water-fountain sample accounts for a large fraction of the systems in our Galaxy which have just experienced the common-envelope phase. Since water-fountain sources show characteristic fast bipolar outflows, outflows and jets likely play an important role right before, during or immediately after the common-envelope phase.

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Theo Khouri, Wouter Vlemmings, Daniel Tafoya, Andrés F. Pérez-Sánchez, Carmen Sánchez Contreras, José F. Gómez, Hiroshi Imai, Raghvendra Sahai. 2021-12-17. Observational identification of a sample of likely recent Common-Envelope Events. https://doi.org/10.1038/s41550-021-01528-4

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