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arXiv 1607.08623astro-ph.GA
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通过VVV调查约束尘埃消光特性

Constraining Dust Extinction Properties via the VVV Survey

D. Majaess, D. Turner, I. Dekany, D. Minniti, W. Gieren

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To appear in Astronomy and Astrophysics
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摘要：

近红外色余和消光比对于建立宇宙距离尺度和探测银河系至关重要，特别是在分析被大量尘埃衰减的目标时。利用VVV巡天的新红外观测结果对这些比率进行了可靠的确定，其中发现了许多隆起的RR型天琴座和II型造父变星，此外还有占据更广泛银河系的经典造父变星和O型星的$BVJHK_{s}(3.4\rightarrow22)μm$数据。表观光学色余比随银河经度（$\ell$）变化显著，而近红外结果随$\ell$和银心距（$\langle E(J-\overline{3.5μm})/E(J-K_s) \rangle =1.28\pm0.03$）变化相对恒定。结果表明，经典造父变星和O型星显示出不同的光学趋势（$R_{V,BV}$）与$\ell$，这似乎不利于理论主张严格和显着减少尘埃的大小增加银心距离。经典造父变星、II型造父变星和天琴座RR型变星的特征是$\langle A_{J}/E(J-K_s) \rangle = \langle R_{J,JK_s} \rangle =1.49\pm0.05$（$\langle A_{K_s}/A_J \rangle =0.33\pm0.02$），而O型变星则受到$3.6 μm$以外的辐射的影响。经典造父变星和O型星的平均光学比分别约为$\langle R_{V,BV} \rangle \sim3.1$和$\langle R_{V,BV} \rangle \sim3.3$。

英文摘要：

Near-infrared color-excess and extinction ratios are essential for establishing the cosmic distance scale and probing the Galaxy, particularly when analyzing targets attenuated by significant dust. A robust determination of those ratios followed from leveraging new infrared observations from the VVV survey, wherein numerous bulge RR Lyrae and Type II Cepheids were discovered, in addition to $BVJHK_{s}(3.4\rightarrow22)μm$ data for classical Cepheids and O-stars occupying the broader Galaxy. The apparent optical color-excess ratios vary significantly with Galactic longitude ($\ell$), whereas the near-infrared results are comparatively constant with $\ell$ and Galactocentric distance ($\langle E(J-\overline{3.5μm})/E(J-K_s) \rangle =1.28\pm0.03$). The results derived imply that classical Cepheids and O-stars display separate optical trends ($R_{V,BV}$) with $\ell$, which appear to disfavor theories advocating a strict and marked decrease in dust size with increasing Galactocentric distance. The classical Cepheid, Type II Cepheid, and RR Lyrae variables are characterized by $\langle A_{J}/E(J-K_s) \rangle = \langle R_{J,JK_s} \rangle =1.49\pm0.05$ ($\langle A_{K_s}/A_J \rangle =0.33\pm0.02$), whereas the O-stars are expectedly impacted by emission beyond $3.6 μm$. The mean optical ratios characterizing classical Cepheids and O-stars are approximately $\langle R_{V,BV} \rangle \sim3.1$ and $\langle R_{V,BV} \rangle \sim3.3$, respectively.

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