AI 中文总结
该研究利用新观测重新分析TOI-4438和TOI-442行星系统，结合TESS凌日数据与SPIRou光谱，联合拟合光度和RV模型，精确测定行星参数，提高精度，还比较RV模型，发现考虑恒星变化信号的模型对行星参数约束更好。
AI 中文摘要
我们对两个恒星-行星系统进行了全面的重新分析：TOI-4438，一颗M3.5V恒星，其轨道周期为7.4天，拥有一颗迷你海王星；TOI-442，一颗M1V恒星，其轨道周期为4天的行星位于热海王星沙漠内。这两个系统最初由TESS识别为凌日行星候选体，并随后通过径向速度（RV）方法得到验证。我们的工作纳入了新的TESS凌日数据和来自SPIRou近红外光谱偏振仪的高分辨率光谱。我们在TOI-442中检测到持续且相对较强的塞曼信号，而TOI-4438表现出较弱且间歇性的磁活动，我们从纵向磁场的变化推断出两颗恒星的自转周期。我们对每个系统联合拟合光度和RV模型。对于TOI-4438 b，我们将存档的CARMENES数据与81次SPIRou观测和五个TESS扇区的数据相结合。这得出了一个精确的行星质量$M_{\rm p} = 4.11^{+0.40}_{-0.38}\,M_{\oplus}$和半径$R_{\rm p} = 2.40^{+0.09}_{-0.10}\,R_{\oplus}$，与先前估计值在1.1$\sigma$范围内一致，同时质量精度提高了53%，半径精度提高了22%。对于TOI-442 b，我们在大量存档数据集上增加了29次SPIRou RV测量，显著延长了时间基线。利用一个新的TESS扇区，我们将质量收紧至$M_{\rm p} = 28.38^{+0.77}_{-0.73}\,M_{\oplus}$，半径收紧至$R_{\rm p} = 4.25^{+0.10}_{-0.08}\,R_{\oplus}$，与先前值在1.5$\sigma$范围内一致，质量和半径精度分别提高了46%和67%。在可用的RV数据中我们没有发现额外行星的明显迹象，尽管我们在TOI-4438光曲线中检测到一次单凌日事件。我们比较了各种RV模型，发现考虑恒星变化引起的信号的模型对行星参数的约束有所改善。
英文摘要
We present a comprehensive re-analysis of two star-planet systems: TOI-4438, an M3.5V star hosting a mini-Neptune in a 7.4-day orbit, and TOI-442, an M1V star with a 4-day period planet located within the hot Neptune desert. Both systems were originally identified as transiting planet candidates by TESS and subsequently validated through the radial velocity (RV) method. Our work incorporates new TESS transit data and high-resolution spectroscopy from the SPIRou near-infrared spectropolarimeter. We detect a persistent and relatively strong Zeeman signature in TOI-442, while TOI-4438 exhibits weaker and intermittent magnetic activity, and we infer the stellar rotation periods of both stars from the variability of the longitudinal magnetic field. We jointly fit photometry and RV models for each system. For TOI-4438\,b we combine archival CARMENES data with 81 SPIRou observations and five TESS sectors. This yields a refined planetary mass of $M_{\rm p} = 4.11^{+0.40}_{-0.38}\,M_{\oplus}$ and a radius of $R_{\rm p} = 2.40^{+0.09}_{-0.10}\,R_{\oplus}$, consistent with the previous estimate within 1.1$σ$ while improving by 53\% the precision on the mass and 22\% on the radius. For TOI-442\,b, we add 29 SPIRou RV measurements to an extensive archival dataset, significantly extending the temporal baseline. With a new TESS sector, we tighten the mass to $M_{\rm p} = 28.38^{+0.77}_{-0.73}\,M_{\oplus}$ and radius to $R_{\rm p} = 4.25^{+0.10}_{-0.08}\,R_{\oplus}$, which agrees to the previous values within 1.5$σ$ and improves the precisions by 46\% and 67\% respectively. We find no clear signs of additional planets in the available RV data, although we detect a single-transit event in the TOI-4438 light curve. We compare various RV models and find that those accounting for stellar variability-induced signals yield improved constraints on the planetary parameters.
CommentsAccepted for publication in A&A. 20 pages, 21 figures and 7 tables
