CAREER: Super-Earth or Mini-Neptune? Exploring the Mysterious Origins of the Smallest Transiting Planets

职业：超级地球还是迷你海王星？

• 批准号: 1555095
• 负责人: Heather Knutson
• 金额: $ 46.51万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-15 至 2023-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1555095&HistoricalAwards=false
• 关键词: CAREER; Super; Earth; Mini; Neptune

Ongoing surveys of nearby stars have revealed a diverse array of planetary systems, many of which have characteristics that differ substantially from those of our solar system. Perhaps one of the biggest surprises to come out of these surveys was the discovery that "super-Earths" (planets between 1-10 times the mass of the Earth) are one of the most common types of extrasolar planet. We currently know very little about the compositions of these mysterious planets, and it has been suggested that this mass range may include both "water worlds" and "mini-Neptunes" with thick hydrogen envelopes around a rocky core. THE PI and her students will conduct a carefully-designed observational program to distinguish between these two scenarios and to measure the properties of these exoplanets. These measurements will offer key insights into the formation and migration histories of this surprising new class of planets. This program will support thesis work for two graduate students as well as a series of undergraduate summer research projects. Students will have the opportunity to observe remotely on Keck and to travel to the telescope for observing runs at Palomar.The PI and her students will combine a Keck/HIRES radial velocity campaign with Palomar transit photometry and spectroscopy in order to characterize new low-mass transiting planets and to develop improved cloud models for their atmospheres. They will use radial velocity studies to measure planetary masses, thereby constraining bulk compositions, and they will measure precise orbital ephemerides. For low-density super-Earths, they will use transmission spectroscopy to characterize the mean molecular weight of their atmosphere to distinguish between those that are water-rich and those with rocky cores surrounded by H/He envelopes. Transmission spectroscopy details can be obscured by upper-level clouds, so they will also study "cool Neptunes" in order to develop a better understanding of the cloud formation processes. These observations will utilize new capabilities for precision photometry and spectroscopy at Palomar and significantly enhance the science return from future atmospheric characterization studies with HST and JWST.

对附近恒星的持续调查揭示了各种各样的行星系统，其中许多行星系统的特征与我们太阳系的特征有很大不同。也许这些调查中最大的惊喜之一是发现“超级地球”（质量为地球1-10倍的行星）是最常见的太阳系外行星之一。我们目前对这些神秘行星的组成知之甚少，有人认为这个质量范围可能包括“水世界”和“迷你海王星”，它们在岩石核心周围有厚厚的氢包层。PI和她的学生将进行精心设计的观测计划，以区分这两种情况，并测量这些系外行星的属性。这些测量将为了解这类令人惊讶的新行星的形成和迁移历史提供关键见解。 该计划将支持两名研究生的论文工作以及一系列本科夏季研究项目。学生们将有机会在Keck上进行远程观测，并前往望远镜观察Palomar的运行情况。PI和她的学生将联合收割机将Keck/HIRES径向速度运动与Palomar凌日测光和光谱学结合起来，以描述新的低质量凌日行星的特征，并为它们的大气开发改进的云模型。他们将使用径向速度研究来测量行星质量，从而限制整体组成，他们将测量精确的轨道星历。对于低密度的超级地球，他们将使用透射光谱来表征其大气的平均分子量，以区分那些富含水的和那些被H/He信封包围的岩石核心。透射光谱学的细节可能会被上层云所掩盖，因此他们还将研究“冷海王星”，以便更好地了解云的形成过程。这些观测将利用Palomar的精密光度学和光谱学的新能力，并显着提高HST和JWST未来大气特征研究的科学回报。