Digging into the Interior of Hot Cores with ALMA (DIHCA). II. Exploring the Inner Binary (Multiple) System Embedded in G335 MM1 ALMA1

Abstract

We observed the high-mass protostellar core G335.579–0.272 ALMA1 at ∼200 au (0.″05) resolution with the Atacama Large Millimeter/submillimeter Array (ALMA) at 226 GHz (with a mass sensitivity of 5σ = 0.2 M ⊙ at 10 K). We discovered that at least a binary system is forming inside this region, with an additional nearby bow-like structure (≲1000 au) that could add an additional member to the stellar system. These three sources are located at the center of the gravitational potential well of the ALMA1 region and the larger MM1 cluster. The emission from CH3OH (and many other tracers) is extended (>1000 au), revealing a common envelope toward the binary system. We use CH2CHCN line emission to estimate an inclination angle of the rotation axis of 26° with respect to the line of sight based on geometric assumptions and derive a kinematic mass of the primary source (protostar+disk) of 3.0 M ⊙ within a radius of 230 au. Using SiO emission, we find that the primary source drives the large-scale outflow revealed by previous observations. Precession of the binary system likely produces a change in orientation between the outflow at small scales observed here and large scales observed in previous works. The bow structure may have originated from the entrainment of matter into the envelope due to the widening or precession of the outflow, or, alternatively, an accretion streamer dominated by the gravity of the central sources. An additional third source, forming due to instabilities in the streamer, cannot be ruled out as a temperature gradient is needed to produce the observed absorption spectra.

Direct Observational Evidence of the Multi-scale, Dynamical Mass Accretion Toward a High-mass Star-forming Hub-filament System

“…Observed in other high-mass star-forming HFS clouds (Liu et al 2012(Liu et al , 2022a(Liu et al , 2022bPeretto et al 2013Peretto et al , 2014Kumar et al 2020;Avison et al 2021;Sanhueza et al 2021), this dynamical mass accretion process has been highlighted in the theoretical models such as GHC and I2. Of particular mention are the two most-studied high-mass HFS clouds, SDC335 (Avison et al 2021;Olguin et al 2021Olguin et al , 2022Xu et al 2023) and G34 (Liu et al 2022a), which give detailed observational evidence in strong support of the theoretical predictions.…”

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- XV. Steady Accretion from Global Collapse to Core Feeding in Massive Hub-filament System SDC335

“…At a resolution of ∼ 1000 au by ALMA, SDC335-MM1 further fragments into at least five sources, while molecular line emission is detected in two of the continuum sources, ALMA1 and ALMA3 (Olguin et al 2021). With a more extended array configuration (a resolution of ∼ 200 au), Olguin et al (2022) found that a binary system was forming inside ALMA1, with a nearby bow-like structure ( 1000 au) which could add an additional member to the stellar system. However, those studies lack appropriate temperature tracers so the analyses of fragmentation is limited.…”

“…To address these questions, we use the data from new ALMA observations to investigate the gas motions in a prototypical global-collapse HFS, the IRDC SDC335.579-0.292 (hereafter SDC335; Peretto & Fuller 2009). Located at 3.25 kpc (based on the method from Reid et al 2016) and containing 3.7 × 10 3 𝑀 (Anderson et al 2021), SDC335 (also IRAS 16272-4837) is a well-studied massive starforming region (Garay et al 2002;Peretto et al 2013;Avison et al 2015Avison et al , 2021Olguin et al 2021Olguin et al , 2022.…”

“…These authors believe that the intrinsic velocity gradients are due to the gas flows along the structures. In the case of "the Heart", the largescale filaments are thought to transfer material inwards (Peretto et al 2013) and the identified molecular outflows are evident for ongoing accretion towards MM1 (Avison et al 2021;Olguin et al 2021Olguin et al , 2022. If the gas streams are physically connected to the central massive dense core MM1, then these streams are likely to bridge the large-scale gas inflow along the filaments and play a role in smallscale gas feeding towards the massive dense core MM1 (Avison et al 2021).…”

Digging into the Interior of Hot Cores with the ALMA (DIHCA). III. The Chemical Link between NH2CHO, HNCO, and H2CO

“…In spite of several studies that have investigated the formation processes of NH 2 CHO in star-forming regions, it is still an open question. In this paper, we present observations of the NH 2 CHO, HNCO, H 2 CO, and CH 3 CN ( 13 CH 3 CN) lines toward 30 high-mass star-forming regions covered by the "Digging into the Interior of Hot Cores with ALMA (DIHCA)" survey (Olguin et al 2021(Olguin et al , 2022. The typical angular resolution is 0 3.…”