Abstract

\(UBVJHKLM\) photometry for the carbon Mira star V CrB are presented. The infrared observations were carried out in the time interval 1989–2018, while the \(U\), \(B\), and \(V\) data were obtained in 2001–2014. The light and color curves are analyzed. The pulsation period of V CrB has been found to be \(355\overset{\textrm{d}}{.}2\) in the infrared \(JHKLM\) bands and \(352^{\textrm{d}}\) for the optical \(BV\) band. In the \(JHK\) bands, apart from periodic pulsations, there are distinct sinusoidal variations in the average brightness level with a characteristic period of \({\sim}8300\) days. Color–magnitude relationships have been revealed for the infrared and optical bands. The phase curves exhibit the wavelength dependence of the brightness variability amplitude. The light curves for various bands and colors are discussed. We have constructed the model of a spherically symmetric circumstellar dust envelope that allows the observed spectral energy distribution at both maximum and minimum light to be reproduced equally well (within the model assumptions) and is consistent with the observations of V CrB by differential speckle polarimetry. The model is characterized by the following parameters: the optical depth is \(\tau_{K}=0.33\), the inner and outer radii of the envelope are 8 and 40 000 AU, respectively. The envelope contains spherical carbon dust grains (\(3/4\) by mass) and silicon carbide dust grains. Dust grains with a radius of 0.5 \(\mu\)m account for \(90\%\) of the envelope mass. The remaining \(10\%\) of the mass is accounted for by finer dust with a grain radius of 0.1 \(\mu\)m. Based on the observational data, we have estimated the bolometric flux from V CrB: \(2.6\times 10^{-7}\) and \(5.1\times 10^{-7}\) erg cm\({}^{-2}\) s\({}^{-1}\) at minimum and maximum light, respectively. The effective temperature of the star is \(T_{\textrm{max}}=3000\) K at maximum light and \(T_{\textrm{min}}=2400\) K at minimum light.

中文翻译：

---

碳米拉星V CrB尘埃包络模型的光度法，红外光谱和斑点偏振法

摘要

介绍了碳Mira星V CrB的（UBVJHKLM \）光度法。红外观测是在1989-2018年的时间间隔中进行的，而\（U \），\（B \）和\（V \）的数据则是在2001-2014年获得的。分析光和颜色曲线。在红外\（JHKLM \）波段和\（352 ^ {\ textrm {d}}中，V CrB的脉动周期为\（355 \ overset {\ textrm {d}} {。} 2 \）。\）表示光学\（BV \）波段。在\（JHK \）波段中，除了周期性的脉动外，平均亮度水平还存在明显的正弦变化，其特征周期为\（{\ sim} 8300 \天。已经揭示了红外和光学波段的色度关系。相位曲线表现出亮度变化幅度的波长依赖性。讨论了各种波段和颜色的光曲线。我们构建了一个球形对称的星际尘埃包络模型，该模型使得在最大和最小光下观测到的光谱能量分布都可以很好地重现（在模型假设内），并且与通过差分散斑极化法观测到的V CrB一致。该模型的特征在于以下参数：光学深度为\（\ tau_ {K} = 0.33 \），包络线的内半径和外半径分别为8和40 000 AU。信封包含球形碳尘粒（\（3/4 \）质量）和碳化硅粉尘颗粒。半径为0.5 \（\ mu \） m的灰尘颗粒占包络质量的\（90 \％\）。质量的剩余\（10 \％\）是由颗粒半径为0.1 \（\ mu \） m的较细粉尘引起的。根据观测数据，我们根据V CrB估算了辐射热通量：\（2.6×10 ^ {-7} \）和\（5.1×10 ^ {-7} \） erg cm \（{} ^ {-2} \） s \（{} ^ {-1} \）分别处于最小和最大光线。恒星的有效温度在最大光下为\（T _ {\ textrm {max}} = 3000 \） K，在最小光下为\（T _ {\ textrm {min}} = 2400 \） K。