Collaborative Research: Advanced Wavefront Sensing and Control for Exoplanet Imaging at W. M. Keck Observatory

拍摄其他恒星周围的行星是很困难的，因为恒星比行星亮得多。然而，其他行星的图像也可以告诉我们这颗行星是由什么组成的，它的天气可能是什么样子，它是如何形成的，以及它是否可能是生命的家园。到目前为止，天文学家只成功地拍摄到了太阳系外的少数几颗行星，这些行星异常炎热、明亮，而且距离它们的太阳很远。为了拍摄类地行星(它们很暗，离太阳很近)的照片，天文学家必须克服地球大气层的湍流和望远镜光学系统的缺陷等问题。这个项目将解决这两个问题。将研究一种新的预测控制方法，既能预测即将到来的湍流，又能开发测量和校正望远镜内部光学误差的方法。该项目的调查人员参与了新的“Astrotech”暑期学校的教学和指导工作。来自夏威夷代表性不足和服务不足人群的学生将通过Akamai劳动力计划实习和夏威夷大学希洛分校直接参与这项研究。这些新的方法将在凯克天文台进行演示。在过去的30年里，发现了4000多颗围绕附近恒星运行的系外行星。直接成像是获得不同系外行星大气的高信噪比、高分辨率光谱的首选方法。现代高对比度成像系统的性能受到感测和校正最低阶波前像差的能力的限制，这些像差导致接近望远镜衍射极限的污染星光。该项目将在凯克天文台实施两项技术，以提高空间分辨率。首先，预测波前控制将使波前检测和控制之间的时间滞后的影响最小化，这会导致在低空间频率下快速演化的斑点。其次，焦平面波前控制将仪器像差降至最低，现有的自适应光学系统无法检测到引起波前“斑点”误差的仪器像差。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Taking pictures of planets around other stars is difficult, because stars are much brighter than planets. However, images of other planets can also tell us what the planet is made of, what its weather might be like, how it formed, and whether it might be home to life. So far, astronomers have only managed to image a handful of planets outside the Solar System, and these planets are unusually hot, bright, and far from their suns. To take pictures of Earth-like planets (which are faint and very close to their suns) astronomers must overcome issues like the turbulence in Earth’s atmosphere and imperfections in the telescope optics. This project will tackle both these issues. A new predictive control method will be investigated that both anticipates the upcoming turbulence, and develops methods to measure and correct the internal optical errors of telescopes. The project’s investigators are involved in teaching and mentoring at the new “AstroTech” summer school. Students from underrepresented and underserved populations in Hawaii will be directly involved in this research through Akamai Workforce Initiative internships and through the University of Hawaii at Hilo. These new approaches will be demonstrated at the Keck Observatory.The last three decades have been marked by the discovery of over 4000 exoplanets orbiting nearby stars. Direct imaging is the preferred method for obtaining high signal-to-noise, high-resolution spectra of diverse exoplanet atmospheres. The performance of modern high contrast imaging systems is limited by the ability to sense and correct the lowest order wavefront aberrations that give rise to contaminating starlight close to the telescope’s diffraction limit. This project will implement two technologies at Keck Observatory to improve spatial resolution. Firstly, predictive wavefront control will minimize the effect of time lag between wavefront sensing and control that results in quickly- evolving speckles at low spatial frequencies. Secondly, focal plane wavefront control that minimizes instrument aberrations that are poorly sensed by the existing adaptive optics systems that give rise to wavefront “speckle” errors.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.