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Published April 10, 2025 | Published
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HIP 8522: A Puzzling Young Solar Twin with the Lowest Detected Lithium Abundance

Galarza, Jhon Yana1 ORCID icon
Lorenzo-Oliveira, Diego2 ORCID icon
Ferreira, Thiago3 ORCID icon
Reggiani, Henrique4 ORCID icon
Behmard, Aida5 ORCID icon
Simon, Joshua D.1 ORCID icon
Martioli, Eder2 ORCID icon
López-Valdivia, Ricardo6 ORCID icon
de Almeida, Leandro2 ORCID icon
Jofré, Emiliano7, 8 ORCID icon
El-Badry, Kareem9 ORCID icon
  • 1. ROR icon Carnegie Observatories
  • 2. ROR icon Laboratório Nacional de Astrofísica
  • 3. ROR icon Yale University
  • 4. ROR icon Gemini South Observatory
  • 5. ROR icon American Museum of Natural History
  • 6. ROR icon National Autonomous University of Mexico
  • 7. Universidad Nacional de Córdoba—Observatorio Astronómico de Córdoba, Laprida 854, X5000BGR Córdoba, Argentina
  • 8. ROR icon National Scientific and Technical Research Council
  • 9. ROR icon California Institute of Technology

Abstract

We present HIP 8522, a young solar twin with the lowest detected lithium abundance, potentially a field blue straggler or the result of episodic early accretion. Its stellar parameters (Teff = 5729 ± 7 K, logg = 4.532 ± 0.016 dex, [Fe/H] = 0.005 ± 0.010 dex, and vt = 1.08 ± 0.02 km s−1) and chemical composition were determined via spectroscopic equilibrium using high-resolution spectra (R = 60,000–165,000). The age of HIP 8522 was estimated to have an upper limit of <1 Gyr through isochrone fitting and was further confirmed using chemical clocks. Spectral synthesis of the lithium line at ∼6707.8 Å yielded an upper lithium abundance limit of A(Li) < 0.8 dex. This value is unusually low for solar twins of similar age, which typically have A(Li) values ranging from 2.0 to 3.3 dex, suggesting that ∼2 dex of lithium is missing. We investigate various scenarios, such as planet engulfment, substellar mergers, and extra mixing. However, two distinct hypotheses provide plausible explanations for the significant depletion of lithium: one suggests that HIP 8522 is a field blue straggler formed by the merger of a close binary, while the other proposes that HIP 8522 experienced early episodic accretion. The young solar twin HIP 8522 presents an exceptional opportunity to rigorously test stellar evolution models and gain crucial insights into the internal mixing mechanisms responsible for the significant destruction of lithium.

Copyright and License

© 2025. The Author(s). Published by the American Astronomical Society.

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

J.Y.G. acknowledges support from a Carnegie Fellowship. D.L.O acknowledges the support from CNPq (PCI 301612/2024-2). T.F. acknowledges support from Yale Graduate School of Arts and Sciences. H.R. acknowledges the support from NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. E.M. acknowledges funding from FAPEMIG under project number APQ-02493-22 and a research productivity grant No. 309829/2022-4 awarded by the CNPq, Brazil. R.L-.V. acknowledges support from CONAHCyT through a postdoctoral fellowship within the program "Estancias Posdoctorales por México."

The observations were carried out within the framework of the Subaru–Keck/Subaru–Gemini time exchange program, which is operated by the National Astronomical Observatory of Japan. We are honored and grateful for the opportunity of observing the Universe from Maunakea, which has the cultural, historical and natural significance in Hawaii.

This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This publication makes use of VOSA, developed under the Spanish Virtual Observatory (https://svo.cab.inta-csic.es) project funded by MCIN/AEI/10.13039/501100011033/ through grant PID2020-112949GB-I00. VOSA has been partially updated by using funding from the European Union's Horizon 2020 Research and Innovation Program, under grant Agreement No.776403 (EXOPLANETS-A).

Facilities

Smith (Robert G. Tull Coudé Spectrograph) - , Subaru (The High Dispersion Spectrograph) - , Magellan:Clay (The Magellan Inamori Kyocera Echelle) - , OHP (SOPHIE Echelle Spectrograph) - .

Software References

numpy (S. van der Walt et al. 2011), matplotlib (J. D. Hunter 2007), pandas (W. McKinney 2010), astroquery (A. Ginsburg et al. 2019), iraf (D. Tody 1986), iSpec (S. Blanco-Cuaresma et al. 2014; S. Blanco-Cuaresma 2019), Kapteyn package (J. P. Terlouw & M. G. R. Vogelaar 2015), moog (C. A. Sneden 1973), q2 (I. Ramírez et al. 2014), Gala (A. M. Price-Whelan 2017), astrobase (W. Bhatti et al. 2021), VOSA (A. Bayo et al. 2008).

Additional Information

This research is based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan (NAOJ). We are honored and grateful for the opportunity of observing the Universe from the Maunakea, which has cultural, historical, and natural significance in Hawaii. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory (LCO), Chile.

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