Highly Variable Young Massive Stars in Atlasgal Clumps

Kumar, M. S. N.; Peña, C. Contreras; Lucas, P. W.

doi:10.3847/0004-637x/833/1/24

Cited by 13 publications

(16 citation statements)

References 38 publications

(42 reference statements)

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“…Such a High-Mass system could be self-gravitating and dynamically unstable. This may explain the episodic nature of the H 2 O maser jet (Motogi et al 2016), by causing a shorttime (∼ 1 year) variation of the accretion rate (e.g., Machida 2014, and references therein), as suggested in recent NIR observations toward several HMYSOs (e.g., Kumar et al 2016). Otherwise, the results may simply imply smaller β in the system.…”

Section: Origin Of the Continuum Emissionmentioning

confidence: 83%

A Face-on Accretion System in High-mass Star Formation: Possible Dusty Infall Streams within 100 AU

Motogi

Hirota

Saito

et al. 2017

ApJ

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We report on interferometric observations of a face-on accretion system around the High-Mass young stellar object, G353.273+0.641. The innermost accretion system of 100 au radius was resolved in a 45 GHz continuum image taken with the Jansky-Very Large Array. Our spectral energy distribution analysis indicated that the continuum could be explained by optically thick dust emission. The total mass of the dusty system is ∼ 0.2 M ⊙ at minimum and up to a few M ⊙ depending on the dust parameters. 6.7 GHz CH 3 OH masers associated with the same system were also observed with the Australia Telescope Compact Array. The masers showed a spiral-like, non-axisymmetric distribution with a systematic velocity gradient. The line-of-sight velocity field is explained by an infall motion along a parabolic streamline that falls onto the equatorial plane of the face-on system. The streamline is quasi-radial and reaches the equatorial plane at a radius of 16 au. This is clearly smaller than that of typical accretion disks in High-Mass star formation, indicating that the initial angular momentum was very small, or the CH 3 OH masers selectively trace accreting material that has small angular momentum. In the former case, the initial specific angular momentum is estimated to be 8 × 10 20 (M * /10 M ⊙ ) 0.5 cm 2 s −1 , or a significant fraction of the initial angular momentum was removed outside of 100 au. The physical origin of such a streamline is still an open question and will be constrained by the higher-resolution (∼ 10 mas) thermal continuum and line observations with ALMA long baselines.

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Section: Origin Of the Continuum Emissionmentioning

confidence: 83%

A Face-on Accretion System in High-mass Star Formation: Possible Dusty Infall Streams within 100 AU

Motogi

Hirota

Saito

et al. 2017

ApJ

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“…4a, SDC13 (Peretto et al 2013(Peretto et al , 2014Williams et al 2018), and in Fig. 1 of Kumar et al (2016). The trapezium cluster and the BN/KL object represent such a pair in the ONC identified by the two dust condensations as the hub (Myers 2009).…”

Section: Stage Iii: Massive Star Formation In the Density Amplified Hubmentioning

confidence: 96%

Unifying low- and high-mass star formation through density-amplified hubs of filaments

Kumar¹,

Palmeirim²,

Arzoumanian

et al. 2020

A&A

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107

164

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Context. Star formation takes place in giant molecular clouds, resulting in mass-segregated young stellar clusters composed of Sun-like stars, brown dwarfs, and massive O-type(50–100 M⊙) stars. Aims. We aim to identify candidate hub-filament systems (HFSs) in the Milky Way and examine their role in the formation of the highest mass stars and star clusters. Methods. The Herschel survey HiGAL has catalogued about 105 clumps. Of these, approximately 35 000 targets are detected at the 3σ level in a minimum of four bands. Using the DisPerSE algorithm we detect filamentary skeletons on 10′ × 10′ cut-outs of the SPIRE 250 μm images (18′′ beam width) of the targets. Any filament with a total length of at least 55′′ (3 × 18′′) and at least 18′′ inside the clump was considered to form a junction at the clump. A hub is defined as a junction of three or more filaments. Column density maps were masked by the filament skeletons and averaged for HFS and non-HFS samples to compute the radial profile along the filaments into the clumps. Results. Approximately 3700 (11%) are candidate HFSs, of which about 2150 (60%) are pre-stellar and 1400 (40%) are proto-stellar. The filaments constituting the HFSs have a mean length of ~10–20 pc, a mass of ~5 × 104 M⊙, and line masses (M∕L) of ~2 × 103 M⊙ pc−1. All clumps with L > 104 L⊙ and L > 105 L⊙ at distances within 2 and 5 kpc respectively are located in the hubs of HFSs. The column densities of hubs are found to be enhanced by a factor of approximately two (pre-stellar sources) up to about ten (proto-stellar sources). Conclusions. All high-mass stars preferentially form in the density-enhanced hubs of HFSs. This amplification can drive the observed longitudinal flows along filaments providing further mass accretion. Radiation pressure and feedback can escape into the inter-filamentary voids. We propose a “filaments to clusters” unified paradigm for star formation, with the following salient features: (a) low-intermediate-mass stars form slowly (106 yr) in the filaments and massive stars form quickly (105 yr) in the hub, (b) the initial mass function is the sum of stars continuously created in the HFS with all massive stars formed in the hub, (c) feedback dissipation and mass segregation arise naturally due to HFS properties, and explain the (d) age spreads within bound clusters and the formation of isolated OB associations.

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“…One might expect variable extinction to influence the light curve more often than variable accretion amongst luminous YSOs. Only a few luminous eruptive variables (> 10 3 L ) have been previously identified: the class I YSO V723 Car (Tapia, Roth & Persi 2015) in NGC 3372 and several distant embedded candidates identified by Kumar et al (2016) from the sample of CP17a as (usually) the most luminous YSOs in their respective SFRs. In addition, a very luminous YSO undergoing episodic accretion, S255IR NIRS3, was recently found by Caratti o Garatti et al (2016).…”

Section: Luminosities and Distancesmentioning

confidence: 99%

Extreme infrared variables from UKIDSS – II. An end-of-survey catalogue of eruptive YSOs and unusual stars

Lucas

Smith

Peña

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present a catalogue of 618 high amplitude infrared variable stars (1 < ∆K < 5 mag) detected by the two widely separated epochs of 2.2 µm data in the UKIDSS Galactic plane survey, from searches covering ∼1470 deg 2 . Most were discovered by a search of all fields at 30 < l < 230 • . Sources include new dusty Mira variables, three new CV candidates, a blazar and a peculiar source that may be an interacting binary system. However, ∼60% are YSOs, based on spatial association with star forming regions at distances ranging from 300 pc to over 10 kpc. This confirms our initial result in Contreras Peña et al. (Paper I) that YSOs dominate the high amplitude infrared variable sky in the Galactic disc. It is also supported by recently published VVV results at 295 < l < 350 • . The spectral energy distributions of the YSOs indicate class I or flat spectrum systems in most cases, as in the VVV sample. A large number of variable YSOs are associated with the Cygnus X complex and other groups are associated with the North America/Pelican nebula, the Gemini OB1 molecular cloud, the Rosette complex, the Cone nebula, the W51 star forming region and the S86 and S236 HII regions. Most of the YSO variability is likely due to variable/episodic accretion on timescales of years, albeit usually less extreme than classical FUors and EXors. Luminosities at the 2010 WISE epoch range from ∼0.1 L to 10 3 L but only rarely exceed 10 2.5 L .

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Highly Variable Young Massive Stars in Atlasgal Clumps

Cited by 13 publications

References 38 publications

A Face-on Accretion System in High-mass Star Formation: Possible Dusty Infall Streams within 100 AU

A Face-on Accretion System in High-mass Star Formation: Possible Dusty Infall Streams within 100 AU

Unifying low- and high-mass star formation through density-amplified hubs of filaments

Extreme infrared variables from UKIDSS – II. An end-of-survey catalogue of eruptive YSOs and unusual stars

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