Extreme Lithium Depletion in Solar Twins: Challenging Non-Standard Mixing Models
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| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Winnick, Isabelle Galarza, Jhon Yana Reggiani, Henrique Ferreira, Thiago Baraffe, Isabelle Lorenzo-Oliveira, Diego Oyague, Micaela Valle, Rita Diaz, Renzo Trujillo Leigh, Nathan Trivigno, Matias Flores Lopez-Valdivia, Ricardo Silva, Gabriela Carvalho Martioli, Eder Perottoni, Helio |
| author_facet | Winnick, Isabelle Galarza, Jhon Yana Reggiani, Henrique Ferreira, Thiago Baraffe, Isabelle Lorenzo-Oliveira, Diego Oyague, Micaela Valle, Rita Diaz, Renzo Trujillo Leigh, Nathan Trivigno, Matias Flores Lopez-Valdivia, Ricardo Silva, Gabriela Carvalho Martioli, Eder Perottoni, Helio |
| contents | Lithium (Li) is a powerful tracer of stellar mixing, gradually depleted in solar twins by non-standard transport below the convective zone. Here, we identify six new solar twins with exceptionally low Li levels that are not explained by current non-standard mixing models and, together with our previously reported anomalous solar twin HIP 8522, suggest a distinct population marked by a violent evolutionary past. Employing high-resolution spectra ($R=60,000 - 165,000$), we infer precise stellar parameters and chemical compositions, including Li abundances. We consider possible scenarios generating enhanced mixing, including planetary engulfment, blue straggler stars (BSSs), and early episodic accretion. Our planet engulfment simulations indicate that only one star may have engulfed an exoplanet, rapidly depleting Li via thermohaline convection. In the BSS scenario, radial velocity data rule out binary mass transfer, revealing no stellar companions but instead two new exoplanets. If these stars are field BSSs, a binary merger is likely though uncertain given that current BSS models focus mostly on stars in open clusters. Using pre-main-sequence episodic accretion models, we find that solar-mass stars can experience enhanced Li depletion without significant beryllium (Be) depletion. This is consistent with the Be abundances measured in two of our stars and represents the most plausible scenario, pending Be measurements for the remaining stars. These unique stars, together with HIP 8522, represent exceptional cases for testing stellar evolution models and probing internal mixing processes in Sun-like stars. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_16513 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Extreme Lithium Depletion in Solar Twins: Challenging Non-Standard Mixing Models Winnick, Isabelle Galarza, Jhon Yana Reggiani, Henrique Ferreira, Thiago Baraffe, Isabelle Lorenzo-Oliveira, Diego Oyague, Micaela Valle, Rita Diaz, Renzo Trujillo Leigh, Nathan Trivigno, Matias Flores Lopez-Valdivia, Ricardo Silva, Gabriela Carvalho Martioli, Eder Perottoni, Helio Solar and Stellar Astrophysics Earth and Planetary Astrophysics Lithium (Li) is a powerful tracer of stellar mixing, gradually depleted in solar twins by non-standard transport below the convective zone. Here, we identify six new solar twins with exceptionally low Li levels that are not explained by current non-standard mixing models and, together with our previously reported anomalous solar twin HIP 8522, suggest a distinct population marked by a violent evolutionary past. Employing high-resolution spectra ($R=60,000 - 165,000$), we infer precise stellar parameters and chemical compositions, including Li abundances. We consider possible scenarios generating enhanced mixing, including planetary engulfment, blue straggler stars (BSSs), and early episodic accretion. Our planet engulfment simulations indicate that only one star may have engulfed an exoplanet, rapidly depleting Li via thermohaline convection. In the BSS scenario, radial velocity data rule out binary mass transfer, revealing no stellar companions but instead two new exoplanets. If these stars are field BSSs, a binary merger is likely though uncertain given that current BSS models focus mostly on stars in open clusters. Using pre-main-sequence episodic accretion models, we find that solar-mass stars can experience enhanced Li depletion without significant beryllium (Be) depletion. This is consistent with the Be abundances measured in two of our stars and represents the most plausible scenario, pending Be measurements for the remaining stars. These unique stars, together with HIP 8522, represent exceptional cases for testing stellar evolution models and probing internal mixing processes in Sun-like stars. |
| title | Extreme Lithium Depletion in Solar Twins: Challenging Non-Standard Mixing Models |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2508.16513 |