| Download | - View final version: Do all low-mass stars undergo extra mixing processes? (PDF, 3.2 MiB)
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| DOI | Resolve DOI: https://doi.org/10.3847/1538-4357/ac87a6 |
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| Author | Search for: Balser, Dana S.ORCID identifier: https://orcid.org/0000-0002-2465-7803; Search for: Wenger, Trey V.1ORCID identifier: https://orcid.org/0000-0003-0640-7787; Search for: Bania, T. M.ORCID identifier: https://orcid.org/0000-0003-4866-460X |
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| Affiliation | - National Research Council of Canada. Herzberg Astronomy and Astrophysics
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| Format | Text, Article |
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| Subject | stellar evolution; planetary nebulae; radio spectroscopy |
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| Abstract | Standard stellar evolution models that only consider convection as a physical process to mix material inside of stars predict the production of significant amounts of ³He in low-mass stars (M < 2 Me), with peak abundances of ³He/H ∼ few × 10−3 by number. Over the lifetime of the Galaxy, this ought to produce ³He/H abundances that diminish with increasing Galactocentric radius. Observations of ³He+ in H II regions throughout the Galactic disk, however, reveal very little variation in the ³He abundance with values of ³He/H similar to the primordial abundance, ( He H 10 / )p 3 5 ~ - . This discrepancy, known as the “³He problem,” can be resolved by invoking in stellar evolution models an extra mixing mechanism due to the thermohaline instability. Here we observe ³He+ in the planetary nebula (PN) J320 (G190.3–17.7) with the Jansky Very Large Array to confirm a previous ³He+ detection made with the Very Large Array that supports standard stellar yields. This measurement alone indicates that not all stars undergo extra mixing. Our more sensitive observations do not detect ³He+ emission from J320 with an rms noise of 58.8 μJy beam−1 after smoothing the data to a velocity resolution of 11.4 km s⁻¹. We estimate an abundance limit of ³He/H ≤ 2.75 × 10−3 by number using the numerical radiative transfer code NEBULA. This result nullifies the last significant detection of ³He+ in a PN and allows for the possibility that all stars undergo extra mixing processes. |
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| Publication date | 2022-09-12 |
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| Publisher | IOP |
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| Licence | |
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| Language | English |
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| Peer reviewed | Yes |
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| Export citation | Export as RIS |
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| Report a correction | Report a correction (opens in a new tab) |
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| Record identifier | ec7b2159-62ea-41c1-98bb-cbfb44d20a97 |
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| Record created | 2023-11-02 |
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| Record modified | 2023-11-02 |
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