He-rich Hot Subdwarf Stars Observed in Gaia DR3 and LAMOST DR7: Carbon and Nitrogen Abundances and Kinematics

0584412 - ASÚ 2025 RIV US eng J - Článek v odborném periodiku
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
Grant CEP: GA ČR(CZ) GA22-34467S
Institucionální podpora: RVO:67985815
Klíčová slova: heavy-metal enrichment * white-dwarfs * 3d kinematics
Obor OECD: Astronomy (including astrophysics,space science)
Impakt faktor: 8.7, rok: 2022
Způsob publikování: 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.
Trvalý link: https://hdl.handle.net/11104/0353290