The Circumbinary Ring of KH 15D
The Circumbinary Ring of KH 15D
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KH 15D 圆周环
DOI：
10.1086/383522
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
R. Murray
中科院分区：
文献类型：
--
作者：
E. Chiang;R. Murray
主序前星星KH 15 D在1913-2003年间的光变曲线可以理解，如果这颗星星是一颗偏心双星的成员，它被一个垂直倾斜的薄尘埃气体环所包围。每当星星的反射运动将其带到环双星环之后时，就会发生日食;日食发生的周期等于双星的轨道周期48.4天。光变曲线的特征，包括食中中心反转的幅度、食相对于双星轨道相位的相位、食外亮度水平、食深、食占空比等，都调制在遮蔽环交点回归的时标上，与历史资料雅阁。环的平均半径接近3 Au，径向宽度可能小于该值。虽然内部边界可以由中央双星管理，但外部边界可能需要一颗外部行星来限制它，防止粘性扩散。环必须垂直翘曲以保持非零倾角。热压力梯度和/或环自重可以容易地强制刚性进动。在未来的几年里，随着环的节点从我们的视线中回归到双星，系统的光变曲线应该近似地回到它以前的行为。近期的观测应该会试图探测到这个系统的中红外线过剩;我们估计环在10-100 μm波长处的通量密度为3 mJy。
The light curves of the pre-main-sequence star KH 15D from the years 1913-2003 can be understood if the star is a member of an eccentric binary that is encircled by a vertically thin, inclined ring of dusty gas. Eclipses occur whenever the reflex motion of a star carries it behind the circumbinary ring; the eclipses occur with a period equal to the binary orbital period of 48.4 days. Features of the light curve, including the amplitude of central reversals during mid-eclipse, the phase of the eclipse with respect to the binary orbit phase, the level of brightness out of eclipse, the depth of the eclipse, and the eclipse duty cycle, are all modulated on the timescale of nodal regression of the obscuring ring, in accord with the historical data. The ring has a mean radius near 3 AU and a radial width that is likely less than this value. While the inner boundary could be shepherded by the central binary, the outer boundary may require an exterior planet to confine it against viscous spreading. The ring must be vertically warped to maintain a nonzero inclination. Thermal pressure gradients and/or ring self-gravity can readily enforce rigid precession. In coming years, as the node of the ring regresses out of our line of sight toward the binary, the light curve from the system should cycle approximately back through its previous behavior. Near-term observations should seek to detect a mid-infrared excess from this system; we estimate the flux densities from the ring to be 3 mJy at wavelengths of 10-100 μm.