Mapping Magnetic Fields near Low-Mass Protostars

Giles Novak博士(西北大学)将开展一项活动，观察13个相对孤立的分子云核中的磁场形态，这些分子云核包含嵌入的低质量原恒星。观测将使用亚毫米高角度分辨率偏振仪(SHARP)进行，这是一个前光学模块，为位于莫纳克亚的加州理工学院亚毫米天文台的功能强大的第二代亚毫米高角度分辨率相机增加了偏振功能。这项调查旨在测试一大类原恒星塌陷模型，这些模型利用磁场作为控制塌缩的主要因素。根据这些模型，磁场调节角动量的传递，从而解决所谓的“角动量问题”，并强烈影响形成新行星的原恒星盘的性质。13个目标中的两个的初步结果表明，偏振水平高于探测阈值。如果这些水平是典型的，磁场调查将提供磁控坍塌模型的决定性测试。作为这项工作的一部分，诺瓦克博士和合作者们将对夏普进行升级，将其转化为可供世界天文学使用的“设施仪器”。这次升级将允许来自世界各地的研究人员使用夏普来研究包括外部星系、演化恒星和银河中心黑洞在内的各种天体。此外，研究人员的研究小组将继续为学生提供建造和使用尖端天文仪器的实践经验，为他们在学术界内外的各种职业做好准备。

Dr. Giles Novak (Northwestern University) will carry out a campaign to observe the magnetic field morphology in 13 relatively isolated molecular cloud cores containing embedded low-mass protostars. The observations will be carried out using the Submillimeter High Angular Resolution Polarimeter (SHARP), a fore-optics module that adds polarimetric capability to the powerful Submillimeter High Angular Resolution Camera generation II camera at the Caltech Submillimeter Observatory on Mauna Kea. The survey is designed to test a wide class of protostellar collapse models that invoke magnetic fields as a dominant factor in controlling the collapse. According to these models, the field regulates the transfer of angular momentum thereby solving the so-called "angular momentum problem", and strongly influences the properties of the protostellar disks out of which new planets are formed. Preliminary results for two of the 13 targets indicate that levels of polarization are above the detection threshold. If these levels are typical, the magnetic field survey will provide a conclusive test of the magnetically-controlled collapse models. The survey data will either rule these models out, or set them on a sound observational footing as an important step in their further development.As a part of this work, Dr. Novak and collaborators will upgrade SHARP to convert it into a "Facility Instrument" available to the world astronomical community. The upgrade will allow investigators from around the world to use SHARP to study a diverse range of objects including external galaxies, evolved stars, and the black hole at the Galactic Center. In addition, the investigator's research group will continue to provide students with hands-on experience in building and using cutting-edge astronomical instrumentation, preparing them for a variety of careers both inside and outside of academia.