The CO Outflow Components Ejected by a Recent Accretion Event in B335

Kim, Chul-Hwan; Lee, Jeong-Eun; Peña, Carlos Contreras; Johnstone, Doug; Herczeg, Gregory J.; Tobin, John J.; Evans II, Neal J.

doi:10.3847/1538-4357/ad1400

Cited by 3 publications

(2 citation statements)

References 66 publications

(105 reference statements)

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“…Interestingly, we observe symmetrical EHV subknots very close to the central sources on both red-and blueshifted sides, suggesting symmetrical mass ejections on both sides likely triggered by the accretion outbursts reported in Chen et al (2021). Similar evidence of a connection between mass ejection and accretion outburst has also been observed for the low-mass protostar B335 (Kim et al 2024) and MYSO S255IR NIRS 3 (Cesaroni et al 2023;Fedriani et al 2023). It is reasonable to assume that the closest EHV subknots N1-1 and S1-1 represent the mass ejection caused by the ongoing accretion outburst, which started 9 yr before the ALMA observations in 2019 October.…”

Section: Episodic Mass Ejection As a Consequence Of Accretion Outburstsupporting

confidence: 82%

“…Besides the infrared and maser variability accompanying accretion outbursts, molecular outflows launched during accretion outbursts could be recorded in the form of separated outflow knots or bullets along the outflow axis (Qiu & Zhang 2009;Chen et al 2016;Kim et al 2024). The separation between various outflow knots could be used to constrain the time interval between each individual accretion outburst (Vorobyov et al 2018;Rohde et al 2022).…”

Section: Introductionmentioning

confidence: 99%

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M17 MIR: A Massive Star Is Forming via Episodic Mass Accretion

Zhou 周,

Chen 陈,

Jiang 江

et al. 2024

ApJL

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We analyzed the Atacama Large Millimeter/submillimeter Array (ALMA) band 6 data for the outbursting massive protostar M17 MIR. The ALMA CO J = 2–1 data reveal a collimated and bipolar north–south outflow from M17 MIR. The blueshifted outflow exhibits four CO knots (N1 to N4) along the outflow axis, while the redshifted outflow appears as a single knot (S1). The extremely high velocity (EHV) emissions of N1 and S1 are jetlike and contain subknots along the outflow axis. Assuming the nearest EHV subknots trace the ejecta from the accretion outbursts in the past decades, a tangential ejection velocity of ∼421 km s−1 is derived for M17 MIR. Assuming the same velocity, the dynamical times of the multiple ejecta, traced by the four blueshifted CO knots, range from 20 to 364 yr. The four blueshifted CO knots imply four clustered accretion outbursts with a duration of tens of years in the past few hundred years. The intervals between the four clustered accretion outbursts are also about tens of years. These properties of the four clustered accretion outbursts are in line with the disk gravitational instability and fragmentation model. The episodic accretion history of M17 MIR traced by episodic outflow suggests that a massive star can form from a lower-mass protostar via frequent episodic accretion events triggered by disk gravitational instability and fragmentation. The first detection of the knotty outflow from an outbursting massive protostar suggests that mass ejections accompanied with accretion events could serve as an effective diagnostic tool for the episodic accretion histories of massive protostars.

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Section: Episodic Mass Ejection As a Consequence Of Accretion Outburstsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

M17 MIR: A Massive Star Is Forming via Episodic Mass Accretion

Zhou 周,

Chen 陈,

Jiang 江

et al. 2024

ApJL

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JWST observations of ¹³CO₂ ice

Brunken,

Rocha,

van Dishoeck

et al. 2024

A&A

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The structure and composition of simple ices can be severely modified during stellar evolution by protostellar heating. Key to understanding the involved processes are thermal and chemical tracers that can be used to diagnose the history and environment of the ice. The 15.2 mu m bending mode of CO_2 in particular has proven to be a valuable tracer of ice heating events but suffers from grain shape and size effects. A viable alternative tracer is the weaker CO_2 isotopologue band at 4.39 mu m, which has now become accessible at high S/N with the James Webb Space Telescope (JWST). In this study we present JWST NIRSpec observations of CO_2 ice in five deeply embedded Class 0 sources that span a wide range in masses and luminosities (0.2 - $L_ ) taken as part of the Investigating Protostellar Accretion Across the Mass Spectrum (IPA) program. The band profiles vary significantly depending on the source, with the most luminous sources showing a distinct narrow peak at 4.38 mu m. We first applied a phenomenological approach with which we demonstrate that a minimum of three to four Gaussian profiles are needed to fit the absorption feature of CO_2 . We then combined these findings with laboratory data and show that a 15.2 mu m CO_2 bending-mode-inspired five-component decomposition can be applied to the isotopologue band, with each component representative of CO_2 ice in a specific molecular environment. The final solution consists of cold mixtures of CO_2 with CH_3OH H_2O and CO as well as segregated heated pure CO_2 ice at 80 K. Our results are in agreement with previous studies of the CO_2 ice band, further confirming that CO_2 is a useful alternative tracer of protostellar heating and ice composition. We also propose an alternative solution consisting only of heated mixtures of CO_2 CH_3OH and CO_2 H_2O ices and warm pure CO_2 ice at 80 K (i.e., no cold CO_2 ices) for decomposing the ice profiles of HOPS 370 and IRAS 20126, the two most luminous sources in our sample that show strong evidence of ice heating resulting in ice segregation.

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Episodicity in accretion-ejection processes associated with IRAS 15398-3359

Guzmán Ccolque,

Fernández López,

Vazzano

et al. 2024

A&A

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The protostar is associated with a bipolar molecular outflow ejected in an nearly northeast-southwest (NE-SW) direction, which has been extensively studied. Previous episodic accretion events have been suggested by this source. Furthermore, the analysis of the morphology and kinematics of the molecular outflow revealed the presence of four bipolar elliptical shock-like structures identified in both lobes. These structures seem to trace different ejections inclined sim 10 from each other on the plane of the sky. This led to the hypothesis that the outflow axis likely precesses and launches material episodically. Since several authors reached the conclusion of the same episodicity scenario by independent observations has become an ideal target to empirically analyze the relationship between accretion and ejection processes. We analyzed ALMA archive observations in Band 6, revealing the presence of low-velocity ($<3.5$ emission from the line to the south and north of the protostar. We studied the morphology and kinematics of the gas; our study seems to support the hypothesis of a precessing episodic outflow. The ALMA observations reveal a north-south (N-S) outflow most likely associated with the protostellar system. This outflow could be older than the well-studied NE-SW outflow. The orientation of the N-S outflow is 50 on the plane of the sky away from that of the NE-SW outflow. We also analyzed the spectral energy distribution of a far away young star and preliminarily discard it as the driver of the SE outflow remnants. The new observations support the hypothesis of strong episodic accretion-ejection events in accompanied by dramatic changes in the orientation of its ejection axis, implying that all the outflows in the region may have been driven by the same protostar.

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The CO Outflow Components Ejected by a Recent Accretion Event in B335

Cited by 3 publications

References 66 publications

M17 MIR: A Massive Star Is Forming via Episodic Mass Accretion

M17 MIR: A Massive Star Is Forming via Episodic Mass Accretion

JWST observations of ¹³CO₂ ice

Episodicity in accretion-ejection processes associated with IRAS 15398-3359

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The CO Outflow Components Ejected by a Recent Accretion Event in B335

Cited by 3 publications

References 66 publications

M17 MIR: A Massive Star Is Forming via Episodic Mass Accretion

M17 MIR: A Massive Star Is Forming via Episodic Mass Accretion

JWST observations of 13CO2 ice

Episodicity in accretion-ejection processes associated with IRAS 15398-3359

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JWST observations of ¹³CO₂ ice