Chromospheric Modeling of the Active M3V Star G 80–21 with RH1.5D

• Published in: The Astrophysical journal Vol. 975; no. 1; pp. 133 - 140
• Main Authors: Liu, Shuai, Wei, Huigang, Shi, Jianrong, Li, Wenxian, Han, Henggeng, Liu, Jifeng, Yang, Shangbin
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.11.2024; IOP Publishing
• Subjects: Calcium; Extrasolar planets; H alpha line; High resolution; Near infrared radiation; Radiative transfer; Spectra; Spectrographs; Stars; Stellar activity; Stellar atmospheres
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad7f55

This study investigates the active regions of the M3.0V star G 80–21 using the observed data from the CARMENES project with synthetic spectra generated by the RH1.5D radiative transfer code. The CARMENES project aims to search for exoplanets around M dwarfs using high-resolution near-infrared and optical echelle spectrographs. By comparing the observed data and models for the chromospheric lines of H α and the bluest Ca ii infrared triplet line, we obtain the best-fit models for this star. The optimal fitting for the observed spectrum of G 80–21 is achieved by employing two active areas in conjunction with an inactive region, with a calcium abundance of [Ca/H] = −0.4. This combination successfully fits all the observed data across varying ratios. The minor active component consistently comprises approximately 18% of the total (ranging from 14% to 20%), which suggests that the minor active component is likely located in the polar regions. Meanwhile, the major active component occupies a variable proportion, ranging from 51% to 82%. Our method allows for the determination of the structure and size of stellar chromospheric active regions by analyzing high-resolution observed spectra.