Observations of high-order multiplicity in a high-mass stellar protocluster

Abstract

The dominant mechanism forming multiple stellar systems in the high-mass regime (M* ≳ 8 M⊙) remained unknown because direct imaging of multiple protostellar systems at early phases of high-mass star formation is very challenging. High-mass stars are expected to form in clustered environments containing binaries and higher-order multiplicity systems. So far only a few high-mass protobinary systems, and no definitive higher-order multiples, have been detected. Here we report the discovery of one quintuple, one quadruple, one triple and four binary protostellar systems simultaneously forming in a single high-mass protocluster, G333.23–0.06, using Atacama Large Millimeter/submillimeter Array high-resolution observations. We present a new example of a group of gravitationally bound binary and higher-order multiples during their early formation phases in a protocluster. This provides the clearest direct measurement of the initial configuration of primordial high-order multiple systems, with implications for the in situ multiplicity and its origin. We find that the binary and higher-order multiple systems, and their parent cores, show no obvious sign of disk-like kinematic structure. We conclude that the observed fragmentation into binary and higher-order multiple systems can be explained by core fragmentation, indicating its crucial role in establishing the multiplicity during high-mass star cluster formation.

揭示大质量恒星团中高阶多星系统的起源

“…个五星、1个人四星、1个三星、4个双星系统和24个单星正 在同步形成(图1(c)~(g)) [6] . 图 1 (网络版彩色)G333.23-0.06的连续谱图像 [6] , 包括澳大利亚望远镜致密阵列(Australia Telescope Compact Array, ATCA)观测获得的连续谱 图像(a)、ALMA观测获得的低空间分辨率连续谱图像(b)和高空间分辨率连续谱图像((c)~(g)).…”

“…图 1 (网络版彩色)G333.23-0.06的连续谱图像 [6] , 包括澳大利亚望远镜致密阵列(Australia Telescope Compact Array, ATCA)观测获得的连续谱 图像(a)、ALMA观测获得的低空间分辨率连续谱图像(b)和高空间分辨率连续谱图像((c)~(g)). 叉号符号表示每颗原恒星的位置, 椭圆代表多星 系统的母云核 Figure 1 (Color online) Continuum images of G333.23-0.06 [6] , including ATCA observations (a), ALMA low-resolution (b) and ALMA highresolution ((c)-(g)) observations. The crosses represent the identified protostellar objects and ellipses show the parent cores of multiple systems…”