A Pathway to the Confirmation and Characterisation of Habitable Alien Worlds

确认和描述宜居外星世界的途径

• 批准号: MR/S035214/1
• 负责人: Heather Cegla
• 金额: $ 156.08万
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FS035214%2F1
• 关键词: Pathway; Confirmation; Characterisation; Habitable; Alien

Are we alone in the Universe? Since the confirmation of the first planets outside our solar system in the 1990s, we have made tremendous progress towards answering this question. Yet, the confirmation of a true Earth-analogue still evades us. On top of this, if we are truly to understand the origins of life in the cosmos, we must also create a complete picture of planetary formation, evolution, and habitability.However, each of these aspects necessitates a detailed knowledge of solar-type stars. This is because we study exoplanets indirectly by analysing their much more luminous host stars. For example, most planet confirmation relies on the Doppler wobble of the host star, induced by the planet. Moreover, we can learn about a planet's dynamical history from mapping its projected orbit as it transits its host star. Hence, stellar surface inhomogeneities can impact planetary interpretations, and can completely swamp the signals from rocky worlds. My research aims to overcome these hurdles. For this, I study stellar surfaces from a two-pronged approach: with state-of-the-art 3D simulations and using transiting planets to empirically probe stellar surfaces.I aim to understand and disentangle a fundamental barrier on the pathway to confirming other Earths: the stellar surface inhomogeneities from convection. Planet confirmation requires a mass measurement, which can be determined from the Doppler shift of the absorption lines in the stellar atmosphere. However, all Sun-like stars are enveloped in boiling plasma, causing hot bubbles of plasma to rise to the surface (inducing blueshifts), where they cool and fall down into the surrounding regions (inducing redshifts). The net result is spurious velocity shifts up to a m/s - completely swamping the tiny signal of an Earth- twin, which is a mere 9 cm/s. These shifts can be even larger if regions of magnetic field concentrate and inhibit the convection. Moreover, as the next generation of spectrographs (e.g. ESPRESSO) come online we are entering an era where it is technologically feasible to detect an Earth-twin signal, making this work extremely time critical.The Sun has shown us convection does not easily average out; we must disentangle its signature to find Earth-like worlds. To do this, I use 3D magnetohydrodynamic simulations to create realistic model stars. With these, I study precisely how convection alters stellar lines, and work to optimise stellar noise reduction techniques. My present work on Solar-analogues indicates we can use the curvature of the stellar lines to remove this noise, but will this work for hotter or cooler stars? How do noise diagnostics behave if a star has a patchy distribution of magnetic field? Which lines are most sensitive to the convection and magnetic fields? These are some of the questions my research aims to answer in the next four to seven years.Of course, these diagnostics are only as reliable as their underlying simulations. I have pioneered a new technique, using transiting planets as probes, to validate these for the first time for main-sequence stars other than the Sun. By subtracting in- from out-of-transit observations, we isolate the starlight behind the planet. With this, I can study the convection behaviour, stellar differential rotation, and determine the 3D trajectory of a planet's orbit - a key feature in understanding its formation and evolution. By applying this technique to a range of systems I will validate the simulations, quantify the impact of convection on planetary dynamic measurements, and contribute to a more global understanding of planet formation and evolution.With this two-pronged approach, I aim to push the frontiers of astronomy towards the future confirmation and characterisation of habitable alien worlds, and help answer whether or not we are truly alone in the Universe.

我们在宇宙中是孤独的吗？自从20世纪90年代确认太阳系外的第一颗行星以来，我们在回答这个问题方面取得了巨大进展。然而，我们仍然无法证实一个真正的地球类似物。最重要的是，如果我们真的想了解宇宙中生命的起源，我们还必须对行星的形成、演化和可居住性有一个完整的了解。然而，每一个方面都需要对类太阳恒星有详细的了解。这是因为我们通过分析它们更明亮的宿主恒星来间接研究系外行星。例如，大多数行星的确认依赖于由行星引起的主恒星的多普勒摆动。此外，我们还可以通过绘制行星凌日时的预计轨道来了解行星的动力学历史。因此，恒星表面的不均匀性会影响行星的解释，并可能完全淹没来自岩石世界的信号。我的研究旨在克服这些障碍。为此，我从双管齐下的方法研究恒星表面：使用最先进的3D模拟和使用凌日行星来经验地探测恒星表面。我的目标是理解和解开在确认其他地球的道路上的一个基本障碍：对流造成的恒星表面不均匀性。确认行星需要进行质量测量，这可以通过恒星大气中吸收谱线的多普勒频移来确定。然而，所有类似太阳的恒星都包裹在沸腾的等离子体中，导致等离子体的热气泡上升到表面（引起蓝移），在那里它们冷却并下降到周围区域（引起红移）。最终的结果是虚假的速度变化高达1米/秒，完全淹没了地球孪生兄弟的微小信号，只有9厘米/秒。如果磁场区域集中并抑制对流，这些变化甚至会更大。此外，随着下一代光谱仪（如ESPRESSO）的上线，我们正在进入一个技术上可行的探测地球孪生信号的时代，这使得这项工作的时间至关重要。太阳告诉我们对流并不容易平均；我们必须解开它的特征，才能找到类地行星。为此，我使用3D磁流体动力学模拟来创建逼真的模型恒星。有了这些，我精确地研究对流如何改变恒星的线条，并努力优化恒星的降噪技术。我目前对太阳类似物的研究表明，我们可以利用恒星线的曲率来消除这种噪音，但这种方法对较热或较冷的恒星有效吗？如果一颗恒星的磁场分布不均匀，那么噪声诊断将如何表现？哪些线对对流和磁场最敏感？这些是我的研究计划在未来4到7年内回答的一些问题。当然，这些诊断的可靠性取决于它们的底层模拟。我开创了一项新技术，利用凌日行星作为探测器，首次在太阳以外的主序星上验证了这些。通过从凌日外的观测中减去凌日内的观测，我们将行星后面的星光分离出来。有了这个，我可以研究对流行为，恒星微分旋转，并确定行星轨道的3D轨迹-这是了解其形成和演化的关键特征。通过将这项技术应用于一系列系统，我将验证模拟，量化对流对行星动态测量的影响，并有助于对行星形成和演化有更全面的了解。通过这种双管齐下的方法，我的目标是推动天文学的前沿，在未来确认和描述可居住的外星世界，并帮助回答我们是否真的是宇宙中唯一的。

项目成果

The CARMENES search for exoplanets around M dwarfs A long-period planet around GJ 1151 measured with CARMENES and HARPS-N data

CARMENES 搜索 M 矮星周围的系外行星 使用 CARMENES 和 HARPS-N 数据测量的 GJ 1151 周围的长周期行星

• DOI: 10.1051/0004-6361/202245053
• 发表时间: 2023
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: Blanco-Pozo J

A Transiting, Temperate Mini-Neptune Orbiting the M Dwarf TOI-1759 Unveiled by TESS

• DOI: 10.3847/1538-3881/ac4af0
• 发表时间: 2022-02
• 期刊: The Astronomical Journal
• 作者: N. Espinoza;E. Pall'e;J. Kemmer;R. Luque;J. Caballero;C. Cifuentes;E. Herrero;V. J. S. B'ejar;S. Stock;K. Molaverdikhani;G. Morello;D. Kossakowski;M. Schlecker;P. Amado;P. Bluhm;M. Cort'es-Contreras;T. Henning;L. Kreidberg;M. Kurster;M. Lafarga;N. Lodieu;J. Morales;M. Oshagh;V. Passegger;A. Pavlov;A. Quirrenbach;S. Reffert;A. Reiners;I. Ribas;E. Rodr'iguez;C. R. L'opez;A. Schweitzer;T. Trifonov;P. Chaturvedi;S. Dreizler;S. Jeffers;A. Kaminski;M. J. L'opez-Gonz'alez;J. Lillo-Box;D. Montes;G. Nowak;S. Pedraz;S. Vanaverbeke;M. Z. Osorio;M. Zechmeister;K. Collins;E. Girardin;P. Guerra;R. Naves;I. Crossfield;E. Matthews;S. Howell;D. Ciardi;E. Gonzales;R. Matson;C. Beichman;J. Schlieder;T. Barclay;M. Vezie;J. Villaseñor;T. Daylan;Ismael Mireies;D. Dragomir;J. Twicken;J. Jenkins;J. Winn;D. Latham;G. Ricker;S. Seager

Three years of HARPS-N high-resolution spectroscopy and precise radial velocity data for the Sun

三年的 HARPS-N 高分辨率光谱和精确的太阳径向速度数据

• DOI: 10.1051/0004-6361/202039350
• 发表时间: 2021
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: Dumusque X

Exploring the stellar surface phenomena of WASP-52 and HAT-P-30 with ESPRESSO

使用 ESPRESSO 探索 WASP-52 和 HAT-P-30 的恒星表面现象

• DOI: 10.1051/0004-6361/202245523
• 发表时间: 2023
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: Cegla H

The Hot Neptune WASP-166 b with ESPRESSO – I. Refining the planetary architecture and stellar variability

热海王星 WASP-166 b 与 ESPRESSO — I. 完善行星结构和恒星变异性

• DOI: 10.1093/mnras/stac2178
• 发表时间: 2022
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Doyle, L.;Cegla, H. M.;Bryant, E.;Bayliss, D.;Lafarga, M.;Anderson, D. R.;Allart, R.;Bourrier, V.;Brogi, M.;Buchschacher, N.
• 通讯作者: Buchschacher, N.