دورية أكاديمية
Ton S 415: a close binary containing an intermediate helium subdwarf discovered with SALT and TESS.
| العنوان: | Ton S 415: a close binary containing an intermediate helium subdwarf discovered with SALT and TESS. |
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| المؤلفون: | Snowdon, E J, Jeffery, C S, Schlagenhauf, S, Dorsch, M, Monageng, I M |
| المصدر: | Monthly Notices of the Royal Astronomical Society; 10/15/2023, Vol. 525 Issue 1, p183-189, 7p |
| مصطلحات موضوعية: | SPECTRAL energy distribution, WHITE dwarf stars, LIGHT curves, HELIUM, LOW mass stars, RED giants, SALT |
| مستخلص: | Hot subdwarfs are early-type low-mass stars lying between the main sequence and the white dwarf sequence. The majority have helium-burning cores and helium-poor surfaces. A minority have helium-rich surfaces. A few, including Ton S 415, have surfaces with between 10 per cent and 90 per cent helium (by number). Their properties are diverse and their origins mostly unknown. Ton S 415 was identified as a suspected binary in a Southern African Large Telescope (SALT) survey of hot subdwarfs from its large radial velocity. Using SALT spectroscopy and Transiting Exoplanet Survey Satellite light curves, we confirm that Ton S 415 is a close binary with an orbital period |$p=84.6460\pm 0.0004\, {\rm min}$| and velocity semi-amplitude |$K=175.5\pm 1.0\, {\rm km\, s^{-1}}$|. Analysis of the SALT spectrum and broad-band spectral energy distribution shows the visible star to have an effective temperature |$T_{\rm eff}=43\, 300\pm 1000\, {\rm K}$| , surface gravity |$\log g/{\rm cm\, s^{-2}}=5.89\pm 0.10$| , surface helium-to-hydrogen ratio log y = −0.62 ± 0.10, radius |$R=0.1074\pm 0.0025\, R_{\odot }$| , and mass |$M=0.33\pm 0.09\, {\rm {\rm M}_{\odot }}$|. By modelling the light curve, we estimate the binary mass ratio to be q = 0.7 ± 0.3 and infer an unseen white dwarf companion with a mass of |$M_{\rm WD}=0.47\pm 0.24\, {\rm {\rm M}_{\odot }}$|. The results are consistent with a post-common-envelope binary that lost its hydrogen envelope before reaching the peak of the red giant branch, becoming a hot subdwarf with a non-canonical mass. We predict that the system will evolve into a double white dwarf binary before eventually either forming a stably accreting AM CVn system, or merging to form an R CrB star. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: | Complementary Index |
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