How Do Stars Gain Their Mass? A JCMT/SCUBA-2 Transient Survey of Protostars in Nearby Star-forming Regions

Herczeg, Gregory J.; Johnstone, Doug; Mairs, Steve; Hatchell, Jennifer; Lee, Jeong Eun; Bower, Geoffrey C.; Chen, Huei-Ru Vivien; Aikawa, Yuri; Yoo, Hyunju; Kang, Sung-Ju; Kang, Miju; Chen, Wen-Ping; Williams, Jonathan P.; Bae, Jaehan; Dunham, Michael M.; Vorobyov, Eduard I.; Zhu, Zhaohuan; Rao, Ramprasad; Kirk, Helen; Takahashi, Satoko; Morata, Ó.; Lacaille, Kevin; Lane, James; Pon, Andy; Scholz, A.; Samal, M. R.; Bell, Graham S.; Graves, Sarah; Lee, E’lisa M.; Parsons, Harriet; He, Yuxin; Zhou, Jianjun; Kim, Mi-Ryang; Chapman, Scott; Drabek-Maunder, E.; Chung, Eun Jung; Eyres, S. P. S.; Forbrich, Jan; Hillenbrand, Lynne A.; Inutsuka, Shu‐ichiro; Kim, Gwanjeong; Kim, Kyoung Hee; Kuan, Yi‐Jehng; Kwon, Woojin; Lai, Shih-Ping; Lalchand, Bhavana; Lee, Chang Won; Lee, Chin-Fei; Long, Feng; Lyo, A-Ran; Qian, Lei; Scicluna, Peter; Soam, Archana; Stamatellos, Dimitris; Takakuwa, Shigehisa; Tang, Ya-Wen; Wang, Hongchi; Wang, Yiren

doi:10.3847/1538-4357/aa8b62

Cited by 56 publications

(49 citation statements)

References 212 publications

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“…At longer wavelengths, Liu, H. et al (2018) found variations in millimeter flux of 30 − 60% toward 2 out of 29 sources using SMA. The James Clerk Maxwell Telescope (JCMT) transient survey monitored 237 sources at submillimeter wavelengths for 18 months (Herczeg et al 2017;Johnstone et al 2018), and they identified only one burst, from the Class I source, EC53.…”

Section: Introductionmentioning

confidence: 99%

Chronology of Episodic Accretion in Protostars—An ALMA Survey of the CO and H₂O Snowlines

Hsieh

Murillo

Беллоче

et al. 2019

ApJ

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Episodic accretion has been used to explain the wide range of protostellar luminosities, but its origin and influence on the star forming process are not yet fully understood. We present an ALMA survey of N 2 H + (1 − 0) and HCO + (3 − 2) toward 39 Class 0 and Class I sources in the Perseus molecular cloud. N 2 H + and HCO + are destroyed via gas-phase reactions with CO and H 2 O, respectively, thus tracing the CO and H 2 O snowline locations. A snowline location at a much larger radius than that expected from the current luminosity suggests that an accretion burst has occurred in the past which has shifted the snowline outward. We identified 18/18 Class 0 and 9/10 Class I post-burst sources from N 2 H + , and 7/17 Class 0 and 1/8 Class I post-burst sources from HCO + . The accretion luminosities during the past bursts are found to be ∼ 10 − 100 L . This result can be interpreted as either evolution of burst frequency or disk evolution. In the former case, assuming that refreeze-out timescales are 1000 yr for H 2 O and 10,000 yr for CO, we found that the intervals between bursts increases from 2400 yr in the Class 0 to 8000 yr in the Class I stage. This decrease in the burst frequency may reflect that fragmentation is more likely to occur at an earlier evolutionary stage when the young stellar object is more prone to instability.

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Section: Introductionmentioning

confidence: 99%

Chronology of Episodic Accretion in Protostars—An ALMA Survey of the CO and H₂O Snowlines

Hsieh

Murillo

Беллоче

et al. 2019

ApJ

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“…Recently, the JCMT-Transient monitoring survey has been searching for variability at the protostellar stage with monthly monitoring of sub-mm continuum emission in eight nearby star-forming regions (Herczeg et al 2017). The first sub-mm variable detected in this survey, EC 53 (Yoo et al 2017), stands out in amplitude relative to other protostars in the 8 fields Johnstone et al 2018).…”

Section: Introductionmentioning

confidence: 99%

The Circumstellar Environment around the Embedded Protostar EC 53

Lee

Aikawa

et al. 2020

ApJ

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EC53 is an embedded protostar with quasi-periodic emission in the near-IR and sub-mm. We use ALMA high-resolution observations of continuum and molecular line emission to describe the circumstellar environment of EC 53. The continuum image reveals a disk with a flux that suggests a mass of 0.075 M ⊙ , much less than the estimated mass in the envelope, and an in-band spectral index that indicates grain growth to centimeter sizes. Molecular lines trace the outflow cavity walls, infalling and rotating envelope, and/or the Keplerian disk. The rotation profile of the C 17 O 3-2 line emission cannot isolate the Keplerian motion clearly although the lower limit of the protostellar mass can be calculated as 0.3 ± 0.1 M ⊙ if the Keplerian motion is adopted. The weak CH 3 OH emission, which is anti-correlated with the H 13 CO + 4-3 line emission, indicates that the water snow line is more extended than what expected from the current luminosity, attesting to bygone outburst events. The extended snow line may persist for longer at the disk surface because the lower density increases the freeze-out timescale of methanol and water.

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“…However, all sources except HOPS 383 (Safron et al 2015) are at the very late Class I or later stage, near the end of the embedded phase (Covey et al 2011;Kóspál et al 2011). Luminosity variations in the earlier embedded phase will be probed by an ongoing submillimeter survey that monitors 182 Class 0/I objects over 3.5 yr (Herczeg et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Probing Episodic Accretion in Very Low Luminosity Objects

Hsieh

Murillo

Беллоче

et al. 2018

ApJ

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Episodic accretion has been proposed as a solution to the long-standing luminosity problem in star formation; however, the process remains poorly understood. We present observations of line emission from N 2 H + and CO isotopologues using the Atacama Large Millimeter/submillimeter Array (ALMA) in the envelopes of eight very low luminosity objects (VeLLOs). In five of the sources the spatial distribution of emission from N 2 H + and CO isotopologues shows a clear anticorrelation. It is proposed that this is tracing the CO snow line in the envelopes: N 2 H + emission is depleted toward the center of these sources, in contrast to the CO isotopologue emission, which exhibits a peak. The positions of the CO snow lines traced by the N 2 H + emission are located at much larger radii than those calculated using the current luminosities of the central sources. This implies that these five sources have experienced a recent accretion burst because the CO snow line would have been pushed outward during the burst because of the increased luminosity of the central star. The N 2 H + and CO isotopologue emission from DCE161, one of the other three sources, is most likely tracing a transition disk at a later evolutionary stage. Excluding DCE161, five out of seven sources (i.e., ∼70%) show signatures of a recent accretion burst. This fraction is larger than that of the Class 0/I sources studied by Jørgensen et al. and Frimann et al., suggesting that the interval between accretion episodes in VeLLOs is shorter than that in Class 0/I sources.

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How Do Stars Gain Their Mass? A JCMT/SCUBA-2 Transient Survey of Protostars in Nearby Star-forming Regions

Cited by 56 publications

References 212 publications

Chronology of Episodic Accretion in Protostars—An ALMA Survey of the CO and H₂O Snowlines

Chronology of Episodic Accretion in Protostars—An ALMA Survey of the CO and H₂O Snowlines

The Circumstellar Environment around the Embedded Protostar EC 53

Probing Episodic Accretion in Very Low Luminosity Objects

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How Do Stars Gain Their Mass? A JCMT/SCUBA-2 Transient Survey of Protostars in Nearby Star-forming Regions

Cited by 56 publications

References 212 publications

Chronology of Episodic Accretion in Protostars—An ALMA Survey of the CO and H2O Snowlines

Chronology of Episodic Accretion in Protostars—An ALMA Survey of the CO and H2O Snowlines

The Circumstellar Environment around the Embedded Protostar EC 53

Probing Episodic Accretion in Very Low Luminosity Objects

Contact Info

Product

Resources

About

Chronology of Episodic Accretion in Protostars—An ALMA Survey of the CO and H₂O Snowlines

Chronology of Episodic Accretion in Protostars—An ALMA Survey of the CO and H₂O Snowlines