Jet multiplicity in the proto-binary system NGC 1333-IRAS4A

Abstract

Context. Owing to the paucity of sub-arcsecond (sub)mm observations required to probe the innermost regions of newly forming protostars, several fundamental questions are still being debated, such as the existence and coevality of close multiple systems. Aims. We study the physical and chemical properties of the jets and protostellar sources in the NGC 1333-IRAS4A proto-binary system using continuum emission and molecular tracers of shocked gas. Methods. We observed NGC 1333-IRAS4A in the SiO(6−5), SO(6 5 −5 4 ), and CO(2−1) lines and the continuum emission at 1.3, 1.4, and 3 mm using the IRAM Plateau de Bure Interferometer in the framework of the CALYPSO large program. Results. We clearly disentangle for the first time the outflow emission from the two sources A1 and A2. The two protostellar jets have very different properties: the A1 jet is faster, has a short dynamical timescale ( 10 3 yr), and is associated with H 2 shocked emission, whereas the A2 jet, which dominates the large-scale emission, is associated with diffuse emission, bends, and emits at slower velocities. The observed bending of the A2 jet is consistent with the change of propagation direction observed at large scale and suggests jet precession on very short timescales (∼200−600 yr). In addition, a chemically rich spectrum with emission from several complex organic molecules (e.g. HCOOH, CH 3 OCHO, CH 3 OCH 3 ) is only detected towards A2. Finally, very high-velocity shocked emission (∼50 km s −1 ) is observed along the A1 jet. An LTE analysis shows that SiO, SO, and H 2 CO abundances in the gas phase are enhanced up to (3−4) × 10 −7 , (1.4−1.7) × 10 −6 , and (3−7.9) × 10 −7 , respectively. Conclusions. The intrinsic different properties of the jets and driving sources in NGC 1333-IRAS4A suggest different evolutionary stages for the two protostars, with A1 being younger than A2, in a very early stage of star formation previous to the hot-corino phase.

Seeds Of Life In Space (SOLIS): The Organic Composition Diversity at 300–1000 au Scale in Solar-type Star-forming Regions*

“…Particularly intriguing is the formamide detection toward the shocked region, in a position that is at the border of the region where SO 2 emits. Note that SO 2 traces fairly well the two jets emitted by A1 and A2, observed in SiO by Santangelo et al (2015) and here unresolved. As in the case of L1157-B1 S.…”

“…Note that in As, as in L1157-B1, no continuum is detected, so that it is very likely a shock site. Supporting this hypothesis, the formamide emission is blueshifted as other tracers of the two jets emanating from A1 and A2, and the emission region coincides with the apex of the SO 2 emission that probes the jets (Santangelo et al 2015).…”

“…While IRAS4-A1 is more than three times brighter at 1.3 mm than its companion, only IRAS4-A2 is associated with a hot corino (Coutens et al 2015;Taquet et al 2015;De Simone et al 2017;López-Sepulcre et al 2017). In addition, IRAS4-A1 drives a fast collimated jet associated with bright H 2 emission, whereas IRAS4-A2 powers a slower and precessing jet (Santangelo et al 2015). These findings suggest that the two Class 0 sources are likely in different evolutionary stages, although it is not possible so far to firmly conclude whether this is due to evolution or rather accretion luminosity effects/bursts (De Simone et al 2017;López-Sepulcre et al 2017).…”

“…Interferometric observations showed that it is a binary system composed of two Class 0 objects separated by 1. 8  (423 au): IRAS4-A1 and IRAS4-A2 (e.g., Looney et al 2000;Santangelo et al 2015;Tobin et al 2016). The overall bolometric luminosity of IRAS4A and its total envelope mass are estimated to be L 9.1 ☉ and M 5.6 ☉ , respectively (Kristensen et al 2012;Karska et al 2013;Tobin et al 2016).…”

Glycolaldehyde in Perseus young solar analogs

“…The sample of sources is based on all the peaks detected in the 1.3mm and 1.4mm continuum images of CALYPSO targets in Perseus (see Codella et al 2014;Santangelo et al 2015; Anderl et al 2016; Maury et al, in preparation). We selected the sources in the Perseus complex, which is a classical laboratory to study low-mass star formation; in particular, the selected sources belong to the most active sites of current star formation in the Perseus cloud: the NGC-1333 and L1448 clusters.…”