亚恒星伴星GQ Lup B的ALMA和MagAO研究
An ALMA and MagAO Study of the Substellar Companion GQ Lup B
摘要:
多波长观测提供了年轻的直接成像行星质量同伴形成的补充观点。本文报道了用ALMA 1.3 mm和Magellan自适应光学(MagAO)H-α、i '、z'和Ys对GQ Lup系统的观测结果。我们估计吸积率为两个组件从所观察到的H-α通量。在我们0.05角秒分辨率的ALMA图中,我们分辨出了GQ Lup A的尘埃盘,但没有发现来自伴星的信号。该盘是紧凑的,半径约为22天文单位,尘埃质量约为6个地球质量,倾角约为56度,表面密度分布非常平坦,表明尘埃颗粒大小的径向变化。在星盘中没有发现空隙或内部空腔,因此不太可能有一个大质量的内部伴星向外散射GQ Lup B。因此,GQ Lup B可能是通过星盘碎裂或星前核心塌陷而在原地形成的。我们还表明,GQ Lup A的磁盘与其自旋轴不一致,可能与GQ Lup B的轨道不一致。对GQ Lup A盘的潮汐截断半径的分析表明,GQ Lup B的轨道可能具有低偏心率。
英文摘要:
Multi-wavelength observations provide a complementary view of the formation of young directly-imaged planet-mass companions. We report the ALMA 1.3 mm and Magellan adaptive optics (MagAO) H-alpha, i', z', and Ys observations of the GQ Lup system, a classical T Tauri star with a 10-40 Mjup substellar companion at ~110 AU projected separation. We estimate the accretion rates for both components from the observed H-alpha fluxes. In our 0.05 arcsec resolution ALMA map, we resolve GQ Lup A's disk in dust continuum, but no signal is found from the companion. The disk is compact, with a radius of ~22 AU, a dust mass of ~6 Earth masses, an inclination angle of ~56 deg, and a very flat surface density profile indicative of a radial variation in dust grain sizes. No gaps or inner cavity are found in the disk, so there is unlikely a massive inner companion to scatter GQ Lup B outward. Thus, GQ Lup B might have formed in situ via disk fragmentation or prestellar core collapse. We also show that GQ Lup A's disk is misaligned with its spin axis, and possibly with GQ Lup B's orbit. Our analysis on the tidal truncation radius of GQ Lup A's disk suggests that GQ Lup B's orbit might have a low eccentricity.
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