arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2006.08595astro-ph.SRastro-ph.EP
收藏

测量碎片盘相函数的挑战。应用于HR\，4796

The challenge of measuring the phase function of debris disks. Application to HR\,4796

J. Olofsson, J. Milli, A. Bayo, Th. Henning, N. Engler

备注：
Accepted for publication in A&A, 13 pages, 11 Figures
发表信息：
A&A 640, A12 (2020)
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

摘要：碎片盘是研究尘埃特性的宝贵系统。因为它们在所有波长下都是光学薄的，我们可以直接了解尘埃颗粒的性质。一个非常有前途的研究它们的技术是测量它们的相函数。由于可以探测更宽范围的散射角，高度倾斜的物体是有希望的目标。相函数通常是通过将观测结果与假设参数化相函数的合成盘模型进行比较来推断的，或者从盘的表面亮度估计它。在这里，我们认为，后者的方法可能是有偏见的，由于投影效应导致沿主轴的非扁平磁盘的列密度增加。我们提出了一种新的方法来解释这些列密度效应。该方法仍然依赖于模型，因为仍然需要一个磁盘模型来估计作为散射角的函数的密度变化。然而，这种方法允许我们估计相位函数的形状，而不必调用任何参数化形式。我们将我们的方法应用于SPHERE/ZIMPOL对HR1，4796的观测，并强调了与以前测量的差异。我们的模拟结果表明，光盘不是垂直平坦的光波长。我们讨论了该方法的一些注意事项，主要是我们的方法对尘埃密度的真实局部增加仍然是盲目的，并且它还不能很容易地应用于角微分成像观测。与以前对HR\，4796的研究类似，我们仍然不能用一个给定的散射理论来解释相函数的形状，这是碎片盘的一个长期存在的问题。尽管如此，我们认为，在这项研究中强调的类似的效果也可以偏置的总强度的相位函数的确定。

英文摘要：

Abridged: Debris disks are valuable systems to study dust properties. Because they are optically thin at all wavelengths, we have direct access to the properties of dust grains. One very promising technique to study them is to measure their phase function. Disks that are highly inclined are promising targets as a wider range of scattering angles can be probed. The phase function is usually either inferred by comparing the observations to synthetic disk models assuming a parametrized phase function, or estimating it from the surface brightness of the disk. We argue here that the latter approach can be biased due to projection effects leading to an increase in column density along the major axis of a non flat disk. We present a novel approach to account for those column density effects. The method remains model dependent, as one still requires a disk model to estimate the density variations as a function of the scattering angle. This method allows us however to estimate the shape of the phase function without having to invoke any parametrized form. We apply our method to SPHERE/ZIMPOL observations of HR\,4796 and highlight the differences with previous measurements. Our modelling results suggest that the disk is not vertically flat at optical wavelengths. We discuss some of the caveats of the approach, mostly that our method remains blind to real local increase of the dust density, and that it cannot yet be readily applied to angular differential imaging observations. Similarly to previous studies on HR\,4796, we still cannot reconcile the full picture using a given scattering theory to explain the shape of the phase function, a long lasting problem for debris disks. Nonetheless, we argue that similar effects as the ones highlighted in this study can also bias the determination of the phase function in total intensity.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑