Exploring the radial velocity variations of RY Lup with VLT/ESPRESSO: Binary versus spot hypotheses

Engineering notes

Engineering notes will be added by the Power for Solar editorial team.

Chinese explanation / 中文解读

中文解读待补充：本站会优先为光伏效率、钙钛矿太阳能电池、储能技术、太阳能热利用、BIPV、并网技术等高价值论文补充中文说明。

Original abstract

Stellar multiplicity is a possible cause for creating protoplanetary disc substructures, as tidal forces from a close-in spectroscopic companion can carve out gaps and shape disc architecture. However, in young, active systems, the radial velocity (RV) signatures are often complicated by stellar activity. We investigate RY Lup, a classical T Tauri star hosting a disc with a ~60 au cavity, where studies with Gaia astrometry and VLT/SPHERE imaging hinted at an unseen companion. Using high-resolution VLT/ESPRESSO spectra and the least-squares deconvolution (LSD) technique, we analyse RV variations over 327 days. We detect significant line profile variations with a periodic signal of ~3.75 days, aligning with prior photometric estimates. The variations are compatible with a close-in binary system at ~0.04 au and a mass ratio of q ~ 0.6. Combined analysis of RV data and ALMA dynamical mass estimates, using 13CO and 18CO, reveals a highly misaligned system. The nearly face-on binary i ~ 13 deg is misaligned to both the inner and outer discs i ~ 50 deg and ~70 deg, respectively. The derived orbital separation is compatible with the inner disc size, with the inner rim at a = 0.12 au, measured from VLTI/GRAVITY, which suggests a highly warped disc structure. Nonetheless, the short orbital period conflicts with the derived eccentricity (e ~ 0.23). To explore alternative explanations, we assess the impact of stellar spots on RV signals. While the LSD deformations can be modelled by different cool spot configurations, a 15% dispersion in retrieved v sin i values -- coupled with the lack of a significant periodic signal -- suggests that spots alone cannot explain the observed variability. As neither hypothesis is ruled out, we recommend future combined RV and interferometric monitoring to clarify the nature of the spectroscopic variability.

Links and sources

• Official / arXiv page
• PDF from original source

Comments