The First Detection of a Protostellar CO Outflow in the Small Magellanic Cloud with ALMA

Tokuda, Kazuki; Zahorecz, Sarolta; Yuri, Kunitoshi,; Higashino, Kosuke; Tanaka, Kei E. I.; Konishi, Ayu; Suzuki, Taisei; Kitano, Naoya; Harada, Naoto; Shimonishi, Takashi; Neelamkodan, Naslim; Fukui, Y.; Kawamura, Akiko; Onishi, Takaharu; Machida, Masahiro N.

doi:10.3847/2041-8213/ac81c1

Cited by 7 publications

(5 citation statements)

References 47 publications

(62 reference statements)

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“…reported inWard et al (2017) for both sources based on highspatial resolution near-infrared integral field spectroscopy. The molecular component of outflows in S07 is recently reported byTokuda et al (2022) with ALMA observations of the CO(3-2) line. The outflows detected in S09 is the second example of CO-traced protostellar outflows found in the SMC.…”

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confidence: 57%

“…Figure 4 shows a comparison of metallicity-scaled molecular abundances for SMC, LMC, and Galactic hot cores. The data of LMC hot cores are adopted from Shimonishi et al (2016aShimonishi et al ( , 2020 and Sewiło et al (2022b), where the N H 2 of ST11, N105 2B/2A, and N113 A1 are reestimated using the same dust opacity data as in this work and dust temperature of T d = 60 K. Abundances for Galactic sources are collected from the literature for a sample of 11-17 hot cores (Sutton et al 1995;MacDonald et al 1996;Helmich & van Dishoeck 1997;Hatchell et al 1998;van der Tak et al 2000;Qin et al 2010;Zernickel et al 2012;Xu & Wang 2013;Gerner et al 2014). In the figure, the lower and upper quartiles of the abundance distributions are plotted with the median value.…”

Section: Molecular Abundancesmentioning

confidence: 99%

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The Detection of Hot Molecular Cores in the Small Magellanic Cloud

Shimonishi

Tanaka

Zhang

et al. 2023

ApJL

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We report the first detection of hot molecular cores in the Small Magellanic Cloud (SMC), a nearby dwarf galaxy with 0.2 solar metallicity. We observed two high-mass young stellar objects in the SMC with the Atacama Large Millimeter/submillimeter Array and detected emission lines of CO, HCO+, H13CO+, SiO, H2CO, CH3OH, SO, and SO2. Compact hot-core regions are traced by SO2, whose spatial extent is about 0.1 pc, and the gas temperature is higher than 100 K based on the rotation diagram analysis. In contrast, CH3OH, a classical hot-core tracer, is dominated by extended (∼0.2–0.3 pc) components in both sources, and the gas temperature is estimated to be 39 − 6 + 8 K for one source. Protostellar outflows are also detected from both sources as high-velocity components of CO. The metallicity-scaled abundances of SO2 in hot cores are comparable among the SMC, Large Magellanic Cloud (LMC), and Galactic sources, suggesting that the chemical reactions leading to SO2 formation would be regulated by elemental abundances. On the other hand, CH3OH shows a large abundance variation within SMC and LMC hot cores. The diversity in the initial condition of star formation (e.g., degree of shielding, local radiation field strength) may lead to the large abundance variation of organic molecules in hot cores. This work, in conjunction with previous hot-core studies in the LMC and outer/inner Galaxy, suggests that the formation of a hot core would be a common phenomenon during high-mass star formation across the metallicity range of 0.2–1 Z⊙. High-excitation SO2 lines will be a useful hot-core tracer in the low-metallicity environments of the SMC and LMC.

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confidence: 57%

Section: Molecular Abundancesmentioning

confidence: 99%

The Detection of Hot Molecular Cores in the Small Magellanic Cloud

Shimonishi

Tanaka

Zhang

et al. 2023

ApJL

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“…Molecular outflows are universally observed around protostars across the Local Group of galaxies (Tokuda et al 2022 and references therein), and their physical characteristics, such as momentum and force, are diverse and somewhat depend on the protostellar luminosity (e.g., Bontemps et al 1996;Beuther et al 2002;Wu et al 2004). Outflows interact with the surrounding gas from the parental core scale to the molecular cloud scale, and their impact on star-forming regions has been discussed (e.g., Lada 1985;Fukui et al 1993;Matzner & McKee 2000;Mac Low & Klessen 2004;Arce et al 2007;Pudritz & Ray 2019).…”

Section: Introductionmentioning

confidence: 99%

Crescent-shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA

Harada¹,

Tokuda

Yamasaki³

et al. 2023

ApJ

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We report on an Atacama Large Millimeter/submillimeter Array study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The 12CO(J = 2–1) images have an angular resolution of ∼1″ (∼250 au) and show high-velocity blueshifted (≳70 km s−1) and redshifted (≳50 km s−1) emissions, which have 3000 au scale crescent-shaped structures around the protostellar disk traced in the 1.3 mm continuum. Because the high-velocity components of the CO emission are associated with the protostar, we concluded that the emission traces the pole-on outflow. The blueshifted outflow lobe has a clear layered velocity gradient with a higher-velocity component located on the inner side of the crescent shape, which can be explained by a model of an outflow with a higher velocity in the inner radii. Based on the directly driven outflow scenario, we estimated the driving radii from the observed outflow velocities and found that the driving region extends over 2 orders of magnitude. The 13CO emission traces a complex envelope structure with arc-like substructures with lengths of ∼1000 au. We identified the arc-like structures as streamers because they appear to be connected to a rotating infalling envelope. DK Cha is useful for understanding characteristics that are visible by looking at nearly face-on configurations of young protostellar systems, providing an alternative perspective for studying the star formation process.

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“…Note that the bolometric luminosity is commonly used as an index for representing the protostellar mass. The correlation between bolometric luminosity and outflow parameters has recently been confirmed in the Magellanic Clouds (Tokuda et al 2019(Tokuda et al , 2022. Therefore, protostellar outflows are significant phenomena for understanding star formation processes in the Universe.…”

Section: Introductionmentioning

confidence: 84%

Secondary Outflow Driven by the Protostar Ser-emb 15 in Serpens

Sato,

Tokuda,

Machida

et al. 2023

ApJ

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We present the detection of a secondary outflow associated with a Class I source, Ser-emb 15, in the Serpens Molecular Cloud. We reveal two pairs of molecular outflows consisting of three lobes, that is, primary and secondary outflows, using Atacama Large Millimeter/submillimeter Array 12CO and SiO line observations at a resolution of ∼318 au. The secondary outflow is elongated approximately perpendicular to the axis of the primary outflow in the plane of the sky. We also identify two compact structures, Sources A and B, within an extended structure associated with Ser-emb 15 in the 1.3 mm continuum emission at a resolution of ∼40 au. The projected sizes of Sources A and B are 137 au and 60 au, respectively. Assuming a dust temperature of 20 K, we estimate the dust mass to be 2.4 × 10−3 M ⊙ for Source A and 3.3 × 10−4 M ⊙ for Source B. C18O line data imply rotational motion around the extended structure, but we cannot resolve rotational motion in Source A and/or B because the angular and frequency resolutions are insufficient. Therefore, we cannot conclude whether Ser-emb 15 is a single or binary system. Thus, either Source A or Source B could drive the secondary outflow. We discuss two scenarios that might explain the driving mechanism of the primary and secondary outflows: the Ser-emb 15 system is (1) a binary system composed of Sources A and B, or (2) a single-star system composed of Source A alone. In either case, the system could be a suitable target for investigating the disk and/or binary formation processes in complicated environments. Detecting these outflows should contribute to understanding complex star-forming environments, which may be common in the star formation processes.

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The First Detection of a Protostellar CO Outflow in the Small Magellanic Cloud with ALMA

Cited by 7 publications

References 47 publications

The Detection of Hot Molecular Cores in the Small Magellanic Cloud

The Detection of Hot Molecular Cores in the Small Magellanic Cloud

Crescent-shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA

Secondary Outflow Driven by the Protostar Ser-emb 15 in Serpens

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