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He-rich Hot Subdwarf Stars Observed in Gaia DR3 and LAMOST DR7: Carbon and Nitrogen Abundances and Kinematics
- 1.0584412 - ASÚ 2025 RIV US eng J - Journal Article
Luo, Y. - Németh, Péter - Wang, K. - Pan, Y.
He-rich Hot Subdwarf Stars Observed in Gaia DR3 and LAMOST DR7: Carbon and Nitrogen Abundances and Kinematics.
Astrophysical Journal Supplement Series. Roč. 271, č. 1 (2024), č. článku 21. ISSN 0067-0049. E-ISSN 1538-4365
R&D Projects: GA ČR(CZ) GA22-34467S
Institutional support: RVO:67985815
Keywords : heavy-metal enrichment * white-dwarfs * 3d kinematics
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 8.7, year: 2022
Method of publishing: Open access
We conducted an analysis of the abundances of He, C, and N in 210 He-rich hot subdwarfs observed within both the Gaia Data Release 3 (DR3) and LAMOST DR7 data sets. This analysis involved fitting the LAMOST spectra with Tlusty/Synspec non-LTE synthetic spectra. By examining the Galactic spatial positions, velocity vectors, and orbital parameters of these stars, we determined their Galactic population memberships utilizing LAMOST radial velocities and Gaia DR3 parallaxes along with proper motions. Our investigation revealed two positive correlations of C and one positive correlation of N with respect to the He abundance. We found a clear C abundance dichotomy where approximately 82% of the stars show N enrichment above the solar value. Moreover, we observed a bimodal distribution of C abundances, prominently evident in both the Galactic thin and thick disks but absent in the halo population. Furthermore, we found that the scenario of the merger channel of double helium white dwarfs is inadequate to explain the formation of C-deficient He-rich hot subdwarfs.
Permanent Link: https://hdl.handle.net/11104/0353290
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Number of the records: 1