Revisiting Proxima with ESPRESSO
Revisiting Proxima with ESPRESSO
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用 ESPRESSO 重温 Proxima
DOI：
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发表时间：
2020
影响因子：
6.5
通讯作者：
F. Zerbi
中科院分区：
文献类型：
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作者：
A. Mascareno;J. Faria;P. Figueira;C. Lovis;M. Damasso;J. Hern'andez;R. Rebolo;S. Cristiani;F. Pepe;N. C. Santos;M. Z. Osorio;V. Adibekyan;S. Hojjatpanah;A. Sozzetti;F. Murgas;M. Abreu;M. Affolter;Y. Alibert;M. Aliverti;R. Allart;C. Prieto;D. Alves;M. Amate;G. Avila;V. Baldini;T. Bandi;S. Barros;Andrea Bianco;W. Benz;F. Bouchy;C. Broeng;Alexandre Cabral;G. Calderone;R. Cirami;J. Coelho;P. Conconi;I. Coretti;C. Cumani;G. Cupani;V. D’Odorico;S. Deiries;B. Delabre;P. Marcantonio;X. Dumusque;D. Ehrenreich;A. Fragoso;L. Genolet;M. Genoni;R. Santos;I. Hughes;O. Iwert;Florian Kerber;J. Knusdstrup;M. Landoni;B. Lavie;J. Lillo;J. Lizon;G. Curto;C. Maire;A. Manescau;C. Martins;Denis Mégevand;A. Mehner;G. Micela;A. Modigliani;P. Molaro;M. Monteiro;M. Monteiro;M. Moschetti;E. Mueller;N. Nunes;L. Oggioni;A. Oliveira;E. Pallé;G. Pariani;L. Pasquini;E. Poretti;J. L. Rasilla;E. Redaelli;Marco Riva;S. Tschudi;P. Santin;P. Santos;A. Segovia;D. Sosnowska;S. Sousa;Paolo Spanò;F. Tenegi;S. Udry;A. Zanutta;F. Zerbi
背景：Proxima b 的发现标志着近年来系外行星科学最重要的里程碑之一。然而，现有径向速度数据的有限精度和恒星活动建模的难度要求对地球质量行星进行确认。目标。我们的目标是使用新型 ESPRESSO 摄谱仪获得的独立测量来确认 Proxima b 的存在，并利用其改进的精度完善行星参数。方法。我们分析了 Proxima (Gl) 的 63 个光谱 ESPRESSO 观测结果 551）于 2019 年拍摄。我们获得了典型径向速度光子噪声为 26 cm s−1 的径向速度测量结果。我们将这些数据与档案光谱观测和新获得的光度测量结果相结合，对恒星活动信号进行建模，并将它们与径向速度（RV）数据中的行星信号分开。我们对 RV 的时间序列和互相关函数的半高全宽进行联合马尔可夫链蒙特卡罗分析，以对数据中存在的行星和恒星信号进行建模，应用高斯过程回归来处理恒星活动信号。结果。我们在 ESPRESSO 数据和组合的 ESPRESSO+HARPS+UVES 数据集中独立确认了 Proxima b 的存在。 ESPRESSO 数据本身显示 Proxima b 的周期为 11.218 ± 0.029 天，最小质量为 1.29 ± 0.13M⊕。在组合数据集中，我们测量的周期为 11.18427 ± 0.00070 天，最小质量为 1.173 ± 0.086M⊕。我们清楚地测量了恒星自转周期 (87 ± 12 d) 及其引起的 RV 信号，但没有证据表明恒星活动是 11.2 天信号的潜在原因。我们发现了第二个短周期信号存在的证据，该信号在 5.15 天出现，半振幅仅为 40 cm s−1。如果是由行星伴星引起的，则其对应的最小质量为 0.29 ± 0.08M⊕。我们发现，对于 Proxima 的情况，互相关函数的半高全宽可以用作亮度变化的代理，并且其随时间的梯度可以用于成功地使 RV 数据免受恒星活动的部分影响。 ESPRESSO 数据中活动引起的 RV 信号显示出振幅向更红波长的趋势。使用摄谱仪红端测量的速度受活动的影响较小，这表明恒星活动是斑点主导的。这可用于创建以活动为主的差分 RV，并可用于解开活动引起的信号和行星引起的信号。收集的数据不包括在短于 50 天的时间内质量超过 0.6M⊕ 的额外同伴的存在。
Context.The discovery of Proxima b marked one of the most important milestones in exoplanetary science in recent years. Yet the limited precision of the available radial velocity data and the difficulty in modelling the stellar activity calls for a confirmation of the Earth-mass planet.Aims.We aim to confirm the presence of Proxima b using independent measurements obtained with the new ESPRESSO spectrograph, and refine the planetary parameters taking advantage of its improved precision.Methods.We analysed 63 spectroscopic ESPRESSO observations of Proxima (Gl 551) taken during 2019. We obtained radial velocity measurements with a typical radial velocity photon noise of 26 cm s−1. We combined these data with archival spectroscopic observations and newly obtained photometric measurements to model the stellar activity signals and disentangle them from planetary signals in the radial velocity (RV) data. We ran a joint Markov chain Monte Carlo analysis on the time series of the RV and full width half maximum of the cross-correlation function to model the planetary and stellar signals present in the data, applying Gaussian process regression to deal with the stellar activity signals.Results.We confirm the presence of Proxima b independently in the ESPRESSO data and in the combined ESPRESSO+ HARPS+UVES dataset. The ESPRESSO data on its own shows Proxima b at a period of 11.218 ± 0.029 days, with a minimum mass of 1.29 ± 0.13M⊕. In the combined dataset we measure a period of 11.18427 ± 0.00070 days with a minimum mass of 1.173 ± 0.086M⊕. We get a clear measurement of the stellar rotation period (87 ± 12 d) and its induced RV signal, but no evidence of stellar activity as a potential cause for the 11.2 days signal. We find some evidence for the presence of a second short-period signal, at 5.15 days with a semi-amplitude of only 40 cm s−1. If caused by a planetary companion, it would correspond to a minimum mass of 0.29 ± 0.08M⊕. We find that forthe case of Proxima, the full width half maximum of the cross-correlation function can be used as a proxy for the brightness changes and that its gradient with time can be used to successfully detrend the RV data from part of the influence of stellar activity. The activity-induced RV signal in the ESPRESSO data shows a trend in amplitude towards redder wavelengths. Velocities measured using the red end of the spectrograph are less affected by activity, suggesting that the stellar activity is spot dominated. This could be used to create differential RVs that are activity dominated and can be used to disentangle activity-induced and planetary-induced signals. The data collected excludes the presence of extra companions with masses above 0.6M⊕at periods shorter than 50 days.
影响因子：
4.8
作者：
H. Giles;A. Cameron;R. Haywood
通讯作者：
H. Giles;A. Cameron;R. Haywood