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Using high-precision spectroscopy to scrutinize solar model atmospheres

使用高精度光谱检查太阳模型大气

基本信息

批准号：
275523552
负责人：
Professor Dr. Wolfgang Schmidt
金额：
--
依托单位：
Institut für Sonnenphysik (KIS)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/275523552?language=en
关键词：
Using precision spectroscopy scrutinize solar

项目摘要

At the German Vacuum-Tower-Telescope (VTT) we recently installed a Laser Frequency Comb, fiber-coupled with the high-resolution spectrograph of the VTT. This setup allows us to determine the absolute wavelengths of the spectral lines between 500 nm and 700 nm with a precision of 10-9.. This corresponds to a Doppler shift of 0.5 ms-1. With this presently unique instrument we intend to perform fundamental observations with unprecedented accuracy as an acid test of our understanding of the solar atmosphere.Together with the absolute wavelength we will measure the instrumental broadening of the spectrograph. This allows us to exactly determine the equivalent widths, the positions and asymmetries of selected spectral lines and to compare these quantities with predictions of solar model atmospheres. The coupling of temperature and velocity pattern of the solar granulation produces a characteristic line asymmetry (known as C-shape) and line shift (known as convective blue shift). With our observations we will scrutinize the validity of theoretical predictions based on complex numerical simulations.Since both line asymmetry and convective blue shift depend on the heliocentric angle, i.e., on the view angle in the solar atmosphere, we are able to disentangle ambiguities in the temperature and velocity distributions. At each location on the Sun we need several hours of observing time to reduce the Doppler shifts caused by near-surface convection and solar oscillations, with their time scales of several minutes and their amplitudes of several 100 ms-1, to values well below 10 ms-1. Thanks to the reproducible absolute calibration with the frequency comb we can reliably combine measurements taken at different times, since systematic effects are eliminated. The experimental inspection of solar model atmospheres is of fundamental importance for astrophysics. These models are used to derive the abundance of heavy elements in the Sun from a comparison of observed and computed line widths. The solar metallicity in turn is used to calibrate stellar abundances. At the same time, solar model atmospheres are essential for the investigation of the solar magnetism; they are the basis for our understanding of radiatively driven magneto-convection in solar active regions. The investigation of the interaction of magnetic and hydrodynamic forces on small scales can only be done on the Sun; it is the basis for the physics of cosmic magnetic fields.As a most valuable spin-off, we will use the identical instrument, together with suitable laboratory lamps, to determine the wavelengths of a series of spectral lines that are of astrophysical interest. We will achieve an accuracy of 0.005 pm (2 ms-1), at least one order of magnitude better than previous measurements.

在德国真空塔望远镜(VTT)，我们最近安装了一个激光频率梳，与VTT的高分辨率光谱仪光纤耦合。这一设置使我们能够以10-9的精度确定500 nm到700 nm之间的谱线的绝对波长。这相当于0.5毫秒-1的多普勒频移。利用这台目前独一无二的仪器，我们打算以前所未有的精度进行基本观测，作为对我们对太阳大气理解的一次尖锐测试。与绝对波长一起，我们将测量光谱仪的仪器展宽。这使我们能够准确地确定选定谱线的等效宽度、位置和不对称性，并将这些量与太阳模型大气的预测进行比较。太阳颗粒的温度和速度模式的耦合产生了特征线不对称(称为C形)和线移(称为对流蓝移)。通过我们的观测，我们将仔细检验基于复杂数值模拟的理论预测的有效性。由于线不对称和对流蓝移都取决于日心角，即太阳大气中的视角，我们能够解开温度和速度分布中的模糊性。在太阳上的每个位置，我们需要几个小时的观测时间，以将近地表对流和太阳振荡引起的多普勒频移减少到远低于10ms-1的值，其时间尺度为几分钟，幅度为几个100ms-1。由于频率梳的可重复性绝对校准，我们可以可靠地组合在不同时间进行的测量，因为系统的影响被消除了。太阳模型大气的实验检验对天体物理学具有重要意义。这些模型被用来从观测和计算的谱线宽度的比较中得出太阳中重元素的丰度。太阳的金属丰度又被用来校准恒星丰度。同时，太阳模型大气对于太阳磁学的研究是必不可少的，它们是我们理解太阳活动区辐射驱动磁对流的基础。在小尺度上研究磁场和流体动力的相互作用只能在太阳上进行，这是宇宙磁场物理的基础。作为最有价值的副产品，我们将使用相同的仪器，加上合适的实验室灯，来确定一系列天体物理感兴趣的谱线的波长。我们将达到0.005 PM(2ms-1)的精度，比以前的测量至少高出一个数量级。

项目成果

期刊论文数量（4）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Absolute velocity measurements in sunspot umbrae

DOI：
10.1051/0004-6361/201832886
发表时间：
2018-04
期刊：
Astronomy & Astrophysics
影响因子：
6.5
作者：
J. Löhner-Böttcher;W. Schmidt;R. Schlichenmaier;H. Doerr;T. Steinmetz;Ronald Holzwarth
通讯作者：
J. Löhner-Böttcher;W. Schmidt;R. Schlichenmaier;H. Doerr;T. Steinmetz;Ronald Holzwarth

LARS: An Absolute Reference Spectrograph for solar observations Upgrade from a prototype to a turn-key system

DOI：
10.1051/0004-6361/201731164
发表时间：
2017-07
期刊：
Astronomy and Astrophysics
影响因子：
6.5
作者：
J. Löhner-Böttcher;W. Schmidt;H. Doerr;T. Kentischer;T. Steinmetz;R. Probst;R. Holzwarth
通讯作者：
J. Löhner-Böttcher;W. Schmidt;H. Doerr;T. Kentischer;T. Steinmetz;R. Probst;R. Holzwarth

Convective blueshifts in the solar atmosphere

太阳大气中的对流蓝移

DOI：
10.1051/0004-6361/201834538
发表时间：
2019
期刊：
Astronomy & Astrophysics
影响因子：
6.5
作者：
Franziska;Löhner-Böttcher;Johannes;Schmidt;Wolfgang;Steinmetz;Holzwarth;Ronald
通讯作者：
Ronald

Convective blueshifts in the solar atmosphere, I. Absolute measurements with LARS of the spectral lines at 6302 {\AA}

太阳大气中的对流蓝移，I 使用 LARS 对 6302 {AA} 处谱线进行的绝对测量