arXiv 1609.085572016-09astro-ph.SR

从星星的颜色了解它们

Learning about stars from their colors

C. Allende Prieto

备注：: 7 pages, 3 figures, to appear in A&A
发表信息：: A&A 595, A129 (2016)
DOI：: 10.1051/0004-6361/201628789

摘要：

我们提出的问题，有多少信息的晚型恒星的大气参数可以检索纯粹的颜色使用标准的测光系统。我们使用来自模型大气的恒星通量进行了数值实验，在分析它们之前注入随机噪声。我们研究了大气参数之间的简并性的存在，并评估了如何以及参数提取取决于可用的光度过滤器的数量和波长跨度，从UV GALEX到中红外WISE通带。我们还考虑了盖亚任务的分光光度法。我们发现，恒星的有效温度可以准确地确定（$σ\sim$ 0.01德克斯或约150 K）时，红化是可以忽略不计的或已知的，仅仅基于光学测光，和精度可以提高一倍，包括红外数据。另一方面，恒星的金属丰度和表面重力不受光学或红外光度测量的限制。然而，通过添加紫外光度法，我们检索这些参数的能力可以显着提高。当红化被认为是一个自由参数，假设它可以完美地建模，我们的实验表明，它可以从其余的参数解开。这项理论研究表明，结合从紫外到中红外的宽带测光允许大气参数和星际消光确定公平的准确性。紫外线通带的使用有助于实质上获得金属度和表面重力，以及打破有效温度和红化之间的简并性。盖亚BP/RP数据可以解开所有的参数，提供恒星SED建模合理。

英文摘要：

We pose the question of how much information on the atmospheric parameters of late-type stars can be retrieved purely from colors using standard photometric systems. We carried out numerical experiments using stellar fluxes from model atmospheres, injecting random noise before analyzing them. We examined the presence of degeneracies among atmospheric parameters, and evaluated how well the parameters are extracted depending on the number and wavelength span of the photometric filters available, from the UV GALEX to the mid-IR WISE passbands. We also considered spectrophotometry from the Gaia mission. We find that stellar effective temperatures can be determined accurately ($σ\sim$ 0.01 dex or about 150 K) when reddening is negligible or known, based merely on optical photometry, and the accuracy can be improved twofold by including IR data. On the other hand, stellar metallicities and surface gravities are fairly unconstrained from optical or IR photometryy. However, our ability to retrieve these parameters can improve significantly by adding UV photometry. When reddening is considered a free parameter, assuming it can be modeled perfectly, our experiments suggest that it can be disentangled from the rest of the parameters. This theoretical study indicates that combining broad-band photometry from the UV to the mid-IR allows atmospheric parameters and interstellar extinction to be determined with fair accuracy. The use of UV passbands helps substantially to derive metallicities and surface gravities, as well as to break the degeneracy between effective temperature and reddening. The Gaia BP/RP data can disentangle all the parameters, provided the stellar SEDs are modeled reasonably well.

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