Collaborative Research: Determining Properties of Brown Dwarf Atmospheres With High-Precision Spectro-Polarimetry

在银河系中形成的质量小于太阳质量8%的天体无法维持成为真正星星所必需的核聚变。 这些亚恒星物体被称为褐矮星（BD），在许多方面与我们太阳系中的气体巨行星相似，但也有显着的差异。 加州理工学院和加州大学伯克利分校之间的研究合作将观察太阳系外的棕矮星和巨行星（太阳系外巨行星：EGP），以更好地了解这些相似性和差异。 研究人员将使用望远镜对BD和EGP进行广泛的天文调查。他们的新观察将提供必要的信息，以帮助理解EGPs的形成和物理特性。 这项工作将涉及两所大学的研究生和本科生，研究人员将在帕洛玛天文台的绿道游客中心开发一个关于BD和系外行星的新展览，借鉴他们的研究活动和结果。棕矮星和太阳系外巨行星的近红外（NIR）发射光谱是由凝结云和薄雾形成的，但缺乏对这些云的空间分布和微观物理的详细描述。其结果是，大气检索代码产生退化的丰度结果时，适用于当前典型的低分辨率，低信噪比EGP光谱。 该计划将为BD和EGP提供光谱偏振NIR序列，以告知新一代三维建模工具，将全球环流模型和云微物理学结合起来。其结果将是一个大规模的调查光谱偏振云签名的BD，辅之以一个较小的光谱偏振调查的同伴BD和EGP，在近红外（J和H波段）。与测光相比，旋光法对云和霾的存在和表面分布更敏感。 这项研究计划将最终帮助区分形成途径，如恒星状云坍缩，行星状盘不稳定性和核心acceleration.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Objects that form in the Galaxy with masses less than about 8% that of the Sun cannot sustain the nuclear fusion necessary to become a true star. These substellar objects, called brown dwarfs (BDs), are similar in many ways to the gas giant planets in our own Solar System, but there are significant differences. A research collaboration between California Institute of Technology and the University of California-Berkeley will observe both brown dwarfs and giant planets outside the solar system (extra-solar giant planets: EGPs) to better understand these similarities and differences. The researchers will carry out an extensive astronomical survey of BDs and EGPs using telescopes. Their new observations will provide essential information to help understand the formation and physical properties of EGPs. The work will involve graduate and undergraduate students at both universities, and the investigators will develop a new exhibit on BDs and exoplanets at Palomar Observatory's Greenway Visitor Center, drawing on activities and results from their research. The near-infrared (NIR) emission spectra of brown dwarfs and extra-solar giant planets are shaped by condensate clouds and hazes, but a detailed description of these clouds' spatial distributions and microphysics is lacking. As a result, atmospheric retrieval codes yield degenerate abundance results when applied to current typically low-resolution, low signal-to-noise EGP spectroscopy. This program will provide a spectro-polarimetric NIR sequence for BDs and EGPs in order to inform a new generation of three-dimensional modeling tools, incorporating global circulation models and cloud microphysics. The outcome will be a large-scale survey of spectro-polarimetric cloud signatures in BDs, complemented with a smaller spectro-polarimetric survey of companion BDs and EGPs, in the NIR (J and H bands). Compared with photometry, polarimetry is more sensitive to the presence and surface distribution of clouds and hazes. The proposed survey will ultimately help differentiate between formation pathways such as star-like cloud collapse, planet-like disk instability, and core accretion.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.