到CW Leo的独立距离估计
An independent distance estimate to CW Leo
摘要：
在2009年10月至2012年6月期间，用赫歇尔卫星上的SPIRE仪器对狮子座CW进行了六次观测。已检测到的变化，由中央恒星发出的流量与639 \pm 4天的周期，在良好的协议与文献中的测定。变异性也被检测到在CW狮子座周围的弓形激波，以前已经检测到的紫外线和赫歇尔PACS/SPIRE数据。虽然很难直接证明，但我们的工作假设是，这种变化与中央恒星的变化直接相关。在这种情况下，用固定为639天的周期拟合正弦曲线，导致弓形激波和中心恒星之间的变化时滞为402 \pm 37天。弓形激波相对于天空平面的方向是未知的（但见下文）。对于零度的倾角，观测到的时间滞后转化为到CW狮子座的距离为130 \pm 13 pc，对于非零倾角，该距离较小。用分析模型（Wilkin 1996）拟合弓形激波的形状，就可以估计倾角对距离的影响。另外假设星际介质（ISM）和狮子座CW之间的相对特殊速度完全由恒星相对于当地静止标准（即静止ISM）的空间速度决定，根据观测到的自行和径向速度，发现倾斜角为（-33.3 \pm 0.8）度。使用威尔金模型，我们目前对狮子座CW距离的最佳估计是123 \pm 14 pc。对于123秒差距的距离，我们得出的平均光度为7790 \pm 150 Lsol（内部误差）。
英文摘要：
CW Leo has been observed six times between October 2009 and June 2012 with the SPIRE instrument on board the Herschel satellite. Variability has been detected in the flux emitted by the central star with a period of 639 \pm 4 days, in good agreement with determinations in the literature. Variability is also detected in the bow shock around CW Leo that had previously been detected in the ultraviolet and Herschel PACS/SPIRE data. Although difficult to prove directly, our working hypothesis is that this variability is directly related to that of the central star. In this case, fitting a sine curve with the period fixed to 639 days results in a time-lag in the variability between bow shock and the central star of 402 \pm 37 days. The orientation of the bow shock relative to the plane of the sky is unknown (but see below). For an inclination angle of zero degrees, the observed time-lag translates into a distance to CW Leo of 130 \pm 13 pc, and for non-zero inclination angles the distance is smaller. Fitting the shape of the bow shock with an analytical model (Wilkin 1996), the effect of the inclination angle on the distance may be estimated. Making the additional assumption that the relative peculiar velocity between the interstellar medium (ISM) and CW Leo is determined entirely by the star space velocity with respect to the local standard of rest (i.e. a stationary ISM), the inclination angle is found to be (-33.3 \pm 0.8) degrees based on the observed proper motion and radial velocity. Using the Wilkin model, our current best estimate of the distance to CW Leo is 123 \pm 14 pc. For a distance of 123 pc, we derive a mean luminosity of 7790 \pm 150 Lsol (internal error).
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
