论文标题
从$ε$ eridani中检测2 $ - $ 4 GHz连续排放
Detection of 2$-$4 GHz Continuum Emission from $ε$ Eridani
论文作者
论文摘要
附近的恒星$ \rmε\ eridani $一直是无线电调查的恒星排放和外部智能的目标。使用非常大的阵列使用深$ \ rm 2-4 \ ghz $观察值，我们发现了$ 29 \μ{\ rm jy} $ compact，稳定的连续无线电源与$ \ rmε\ rmε\ eridani $相吻合。将我们的数据与以前的高频连续探测$ \ rmε\ eridani $相结合，我们的观察结果显示，频谱周转率在$ \ rm 6 \ ghz $中。我们将$ \ rm 2-6 \ ghz $发射归因于恒星电晕的光学厚度，热旋风辐射，没有热的免费不透明度可能会在低于$ \ rm 1 \ ghz $的频率上相关。 $ \ rm 2-6 \ ghz $频谱的陡峭频谱指数（$α\ simeq 2 $）强烈不散发其解释为恒星风相关的热bremsstrahlung（$α\ simeq 0.6 $）。 Attributing the entire observed $\rm 2-4 \ GHz$ flux density to thermal free-free wind emission, we thus, derive a stringent upper limit of $3 \times 10^{-11} \ M_{\odot} \ {\rm yr}^{-1}$ on the mass loss rate from $\rm ε\ Eridani$.最后，我们在数据上报告了$ \ rm 95 \μjy$的$5σ$阈值的未检测。加上2019年最新恒星最大值的光学非检测，我们的观察结果假定了内部发电机的可能演变为$ \ rmε\ eridani $。
The nearby star $\rm ε\ Eridani$ has been a frequent target of radio surveys for stellar emission and extraterrestial intelligence. Using deep $\rm 2-4 \ GHz$ observations with the Very Large Array, we have uncovered a $29 \ μ{\rm Jy}$ compact, steady continuum radio source coincident with $\rm ε\ Eridani$ to within 0.06 arcseconds ($\lesssim 2σ$; 0.2 au at the distance of the star). Combining our data with previous high frequency continuum detections of $\rm ε\ Eridani$, our observations reveal a spectral turnover at $\rm 6 \ GHz$. We ascribe the $\rm 2-6 \ GHz$ emission to optically thick, thermal gyroresonance radiation from the stellar corona, with thermal free-free opacity likely becoming relevant at frequencies below $\rm 1 \ GHz$. The steep spectral index ($α\simeq 2$) of the $\rm 2-6 \ GHz$ spectrum strongly disfavors its interpretation as stellar wind-associated thermal bremsstrahlung ($α\simeq 0.6$). Attributing the entire observed $\rm 2-4 \ GHz$ flux density to thermal free-free wind emission, we thus, derive a stringent upper limit of $3 \times 10^{-11} \ M_{\odot} \ {\rm yr}^{-1}$ on the mass loss rate from $\rm ε\ Eridani$. Finally, we report the non-detection of flares in our data above a $5σ$ threshold of $\rm 95 \ μJy$. Together with the optical non-detection of the most recent stellar maximum expected in 2019, our observations postulate a likely evolution of the internal dynamo of $\rm ε\ Eridani$.
