تقرير
ELM of ELM-WD: An extremely low mass hot star discovered in LAMOST survey
| العنوان: | ELM of ELM-WD: An extremely low mass hot star discovered in LAMOST survey |
|---|---|
| المؤلفون: | Yuan, Hailong, Li, Zhenwei, Bai, Zhongrui, Dong, Yiqiao, Wang, Mengxin, Yu, Sicheng, Chen, Xuefei, Zhao, Yongheng, Chu, Yaoquan, Zhang, Haotong |
| سنة النشر: | 2022 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics |
| الوصف: | The Extremely Low Mass White Dwarfs (ELM WDs) and pre-ELM WDs are helium core white dwarfs with mass $<\sim 0.3M_{\odot}$. Evolution simulations show that a lower mass limit for ELM WDs exists at $\approx0.14M_{\odot}$ and no one is proposed by observation to be less massive than that. Here we report the discovery of a binary system, LAMOST J224040.77-020732.8 (J2240 in short), which consists of a very low mass hot star and a compact companion. Multi-epoch spectroscopy shows an orbital period $P_{orb} =$0.219658$\pm0.000002$ days and a radial velocity semi-amplitude $K1=318.5\pm3.3km/s$, which gives the mass function of 0.74$M_{\odot}$, indicating the companion is a compact star. The F-type low resolution spectra illustrate no emission features, and the temperature ($\sim 7400K$) is consistent with that from Spectral Energy Distribution fitting and multi-color light curve solution. The optical light curves, in ZTF g, r and i bands and Catalina V band, show ellipsoidal variability with amplitudes $\sim30\%$, suggesting that the visible component is heavily tidally distorted. Combining the distance from Gaia survey, the ZTF light curves are modeled with Wilson-Devinney code and the result shows that the mass of the visible component is $M1=0.085^{+0.036}_{-0.024}M_{\odot}$, and the mass of the invisible component is $M2=0.98^{+0.16}_{-0.09}M_{\odot}$. The radius of the visible component is $R1=0.29^{+0.04}_{-0.03}R_{\odot}$. The inclination angle is approximately between 60$^{\circ}$ and 90$^{\circ}$. The observations indicate the system is most likely a pre-ELM WD + WD/NS binary, and the mass of pre-ELM is possibly lower than the $0.14M_{\odot}$ theoretical limit. Comment: 18 pages, 10 figures |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/1538-3881/acaf07 |
| URL الوصول: | http://arxiv.org/abs/2209.10386 |
| رقم الأكسشن: | edsarx.2209.10386 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/1538-3881/acaf07 |
|---|