论文标题

麦哲伦云中发光红色超级巨星的特性

Properties of luminous red supergiant stars in the Magellanic Clouds

论文作者

de Wit, S., Bonanos, A. Z., Tramper, F., Yang, M., Maravelias, G., Boutsia, K., Britavskiy, N., Zapartas, E.

论文摘要

有证据表明,一些红色超级巨人(RSG)经历了极端质量损失的短期生活阶段,产生了大量的灰尘。这些发作的爆发阶段有助于剥离进化的巨大恒星的氢化,从而极大地影响了它们的进化。但是,迄今为止,情节质量损失的观察数据有限。本文旨在通过使用Baade望远镜来得出麦哲伦云中14个尘土飞扬源的光谱样品的表面特性。这些特性可用于未来的光谱能量分布拟合研究,以测量从恒星爆发到爆发的当前情况下尘埃的质量损失率。我们应用MARCS模型以获取来自光学TIO频段的有效温度($ t _ {\ rm eff} $)和灭绝($ a_v $)。我们使用$χ^2 $例程来确定获得的光谱的最佳拟合模型。我们使用经验光度关系计算$ t _ {\ rm eff} $,并将其与我们建模的$ t _ {\ rm eff} $进行比较。我们已经确定了一个新的黄色超级巨人,并在光谱镜上确认了八个新的RSG和一个明亮的巨人。此外,我们观察到了一颗超级b [e]恒星,发现光谱类型与以前的分类相比发生了变化,证实了光谱类型数十年来是可变的。对于RSG,我们获得了表面和全局属性,以及灭绝$ A_V $。我们的方法已经拾取了八个新的发光RSG。尽管选择了尘土飞扬的RSG,但鉴于这些进化的恒星的间隔灭绝,我们发现$ a_v $的值不如预期。样品中最引人注目的物体LMC3是一个极其巨大和发光的大量恒星,可以分组为大麦芽云中最大,最发光的RSG(log(l $ _*$ _*$/l $ _ {\ odot}})

There is evidence that some red supergiants (RSGs) experience short lived phases of extreme mass loss, producing copious amounts of dust. These episodic outburst phases help to strip the hydrogen envelope of evolved massive stars, drastically affecting their evolution. However, to date, the observational data of episodic mass loss is limited. This paper aims to derive surface properties of a spectroscopic sample of fourteen dusty sources in the Magellanic Clouds using the Baade telescope. These properties may be used for future spectral energy distribution fitting studies to measure the mass loss rates from present circumstellar dust expelled from the star through outbursts. We apply MARCS models to obtain the effective temperature ($T_{\rm eff}$) and extinction ($A_V$) from the optical TiO bands. We use a $χ^2$ routine to determine the best fit model to the obtained spectra. We compute the $T_{\rm eff}$ using empirical photometric relations and compare this to our modelled $T_{\rm eff}$. We have identified a new yellow supergiant and spectroscopically confirmed eight new RSGs and one bright giant in the Magellanic Clouds. Additionally, we observed a supergiant B[e] star and found that the spectral type has changed compared to previous classifications, confirming that the spectral type is variable over decades. For the RSGs, we obtained the surface and global properties, as well as the extinction $A_V$. Our method has picked up eight new, luminous RSGs. Despite selecting dusty RSGs, we find values for $A_V$ that are not as high as expected given the circumstellar extinction of these evolved stars. The most remarkable object from the sample, LMC3, is an extremely massive and luminous evolved massive star and may be grouped amongst the largest and most luminous RSGs known in the Large Magellanic Cloud (log(L$_*$/L$_{\odot})\sim$5.5 and $R = 1400 \,\ \textrm R_{\odot}$).

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