论文标题
长期近红外亮点亮点oh/ir星星
Long-Term Near-Infrared Brightening of Non-Variable OH/IR Stars
论文作者
论文摘要
认为非变异的OH/IR星星刚刚离开了渐近巨型分支（AGB）阶段。在这种传统的情况下，它们仍然必须表现出由于AGB阶段弹出的尘埃引起的强烈的差异，并且由于恒星质量损失后的偶尔灰尘的扩散，预计灭绝会随着时间的流逝而减少。灭绝的减少使恒星随着时间的流逝显然变得更亮，更蓝，尤其是在近红外（NIR）范围内。我们通过使用2个MASS，UKIDSS和OAOWFC调查数据来寻找对非变量OH/IR星的长期亮度。结果，我们获得了20年（1997-2017）在16个不可变化的OH/IR星的20年期间获得的多上述NIR数据，并且发现所有六个物体都在变亮。五个物体的K频段亮率范围从0.010到0.130 mag yr $^{ - 1} $，这是通过传统图片合理地解释的。但是，一个OH/ir恒星OH31.0-0.2显示出快速的亮度，仅通过尘埃壳的散布来解释。获得三个对象的多色（J-，H-和K波段）数据，即OH25.1-0.3，OH53.6-0.2和OH77.9+0.2。令人惊讶的是，它们似乎都没有变得更蓝，而OH53.6-0.2被发现率为0.013 mag yr $^{ - 1} $（j-k）。我们的发现提出了其他机制，例如恒星特性（温度或光度）的快速变化或一批新的尘埃谷物。
Non-variable OH/IR stars are thought to have just left the asymptotic giant branch (AGB) phase. In this conventional picture, they must still show strong circumstellar extinction caused by the dust ejected during the AGB phase, and the extinction is expected to decrease over time because of the dispersal of the circumstellar dust after the cessation of the stellar mass loss. The reduction of the extinction makes the stars become apparently brighter and bluer with time especially in the near-infrared (NIR) range. We look for such long-term brightening of non-variable OH/IR stars by using 2MASS, UKIDSS, and OAOWFC survey data. As a result, we get multi-epoch NIR data taken over a 20-year period (1997-2017) for 6 of 16 non-variable OH/IR stars, and all six objects are found to be brightening. The K-band brightening rate of five objects ranges from 0.010 to 0.130 mag yr$^{-1}$, which is reasonably explained with the conventional picture. However, one OH/IR star, OH31.0-0.2, shows a rapid brightening, which cannot be explained only by the dispersal of the dust shell. Multi-color (J-, H-, and K-band) data are obtained for three objects, OH25.1-0.3, OH53.6-0.2, and OH77.9+0.2. Surprisingly, none of them appears to have become bluer, and OH53.6-0.2 is found to have been reddened with a rate of 0.013 mag yr$^{-1}$ in (J-K). Our findings suggest other mechanisms such as rapid changes in stellar properties (temperature or luminosity) or a generation of a new batch of dust grains.
