A likely flyby of binary protostar Z CMa caught in action

分类： 天文学 >> 天文学 提交时间： 2023-02-19

Ruobing Dong Hauyu Baobab Liu Nicolas Cuello Christophe Pinte Peter Abraham Eduard Vorobyov Jun Hashimoto Agnes Kospal Eugene Chiang Michihiro Takami Lei Chen Michael Dunham Misato Fukagawa Joel Green Yasuhiro Hasegawa Thomas Henning Yaroslav Pavlyuchenkov Tae-Soo Pyo Motohide Tamura

摘要： Close encounters between young stellar objects in star forming clusters are expected to dramatically perturb circumstellar disks. Such events are witnessed in numerical simulations of star formation, but few direct observations of ongoing encounters have been made. Here we report sub-0".1 resolution Atacama Large Millimeter Array (ALMA) and Jansky Very Large Array (JVLA) observations towards the million year old binary protostar Z CMa in dust continuum and molecular line emission. A point source ~4700 au from the binary has been discovered at both millimeter and centimeter wavelengths. It is located along the extension of a ~2000 au streamer structure previously found in scattered light imaging, whose counterpart in dust and gas emission is also newly identified. Comparison with simulations shows signposts of a rare flyby event in action. Z CMa is a "double burster", as both binary components undergo accretion outbursts, which may be facilitated by perturbations to the host disk by flybys.

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