Disentangling the jet emission from protostellar systems

Santangelo, G.; Murillo, Nadia M.; Nisini, B.; Codella, C.; Bruderer, S.; Lai, Shih-Ping; Dishoeck, E. F. van

doi:10.1051/0004-6361/201526428

Cited by 25 publications

(26 citation statements)

References 15 publications

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“…Santangelo et al (2015a), Ching et al (2016) and Tobin et al (2018) for IRAS4A. Santangelo et al (2015b) and Murillo et al (2018) for VLA 1623. Yeh et al (2008), Kristensen et al (2013), Girart et al (2014) and van der Wiel et al 2019for IRAS 16293.…”

Section: Discussionmentioning

confidence: 93%

A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores

Gouellec

Maury

Guillet

et al. 2020

A&A

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Context. Recent observational progress has challenged the dust grain-alignment theories used to explain the polarized dust emission routinely observed in star-forming cores. Aims. In an effort to improve our understanding of the dust grain alignment mechanism(s), we have gathered a dozen ALMA maps of (sub)millimeter-wavelength polarized dust emission from Class 0 protostars and carried out a comprehensive statistical analysis of dust polarization quantities. Methods. We analyze the statistical properties of the polarization fraction Pfrac and the dispersion of polarization position angles S. More specifically, we investigate the relationship between S and Pfrac as well as the evolution of the product S × Pfrac as a function of the column density of the gas in the protostellar envelopes. We compare the observed trends with those found in polarization observations of dust in the interstellar medium and in synthetic observations of non-ideal magneto-hydrodynamic (MHD) simulations of protostellar cores. Results. We find a significant S ∝ Pfrac−0.79 correlation in the polarized dust emission from protostellar envelopes seen with ALMA; the power-law index significantly differs from the one observed by Planck in star-forming clouds. The product S × Pfrac, which is sensitive to the dust grain alignment efficiency, is approximately constant across three orders of magnitude in envelope column density (from NH2 = 1022 cm−2 to NH2 = 1025 cm−2), with a mean value of 0.36−0.17+0.10. This suggests that the grain alignment mechanism producing the bulk of the polarized dust emission in star-forming cores may not systematically depend on the local conditions such as the local gas density. However, in the lowest-luminosity sources in our sample, we find a hint of less efficient dust grain alignment with increasing column density. Our observations and their comparison with synthetic observations of MHD models suggest that the total intensity versus the polarized dust are distributed at different intrinsic spatial scales, which can affect the statistics from the ALMA observations, for example, by producing artificially high Pfrac. Finally, synthetic observations of MHD models implementing radiative alignment torques (RATs) show that the statistical estimator S × Pfrac is sensitive to the strength of the radiation field in the core. Moreover, we find that the simulations with a uniform perfect alignment (PA) of dust grains yield, on average, much higher S × Pfrac values than those implementing RATs; the ALMA values lie among those predicted by PA, and they are significantly higher than the ones obtained with RATs, especially at large column densities. Conclusions. Ultimately, our results suggest that dust alignment mechanism(s) are efficient at producing dust polarized emission in the various local conditions typical of Class 0 protostars. The grain alignment efficiency found in these objects seems to be higher than the efficiency produced by the standard RAT alignment of paramagnetic grains. Further studies will be needed to understand how more efficient grain alignment via, for example, different irradiation conditions, dust grain characteristics, or additional grain alignment mechanisms can reproduce the observations.

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Section: Discussionmentioning

confidence: 93%

A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores

Gouellec

Maury

Guillet

et al. 2020

A&A

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“…Friesen et al 2018, (2) Kamazaki et al 2003, (3) Bussmann et al 2007, (4) van der Marel et al 2013, (5) Yen et al 2017, (6) Visser et al 2002, (7) van der Wiel et al 2019, (8)Santangelo et al 2015. e VLA 1623A is split into two entries, one for the compact disk with uniform polarization and one from the extended disk with azimuthal polarization.…”

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confidence: 99%

Dust Polarization toward Embedded Protostars in Ophiuchus with ALMA. III. Survey Overview

Sadavoy

Stephens

Myers

et al. 2019

ApJS

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We present 0.25 resolution (35 au) ALMA 1.3 mm dust polarization observations for 37 young stellar objects (YSOs) in the Ophiuchus molecular cloud. These data encompass all the embedded protostars in the cloud and several Flat and Class II objects to produce the largest, homogeneous study of dust polarization on disk scales to date. The goal of this study is to study dust polarization morphologies down to disk scales. We find that 14/37 (38%) of the observed YSOs are detected in polarization at our sensitivity. Nine of these sources have uniform polarization angles and four sources have azimuthal polarization structure. We find that the sources with uniform polarization tend to have steeper inclinations (> 60 • ) than those with azimuthal polarization (< 60 • ). Overall, the majority (9/14) of the detected sources have polarization morphologies and disk properties consistent with dust self-scattering processes in optically thick disks. The remaining sources may be instead tracing magnetic fields. Their inferred field directions from rotating the polarization vectors by 90 • are mainly poloidal or hourglass shaped. We find no evidence of a strong toroidal field component toward any of our disks. For the 23 YSOs that are undetected in polarization, roughly half of them have 3-sigma upper limits of < 2%. These sources also tend to have inclinations < 60 • and they are generally compact. Since lower inclination sources tend to have azimuthal polarization, these YSOs may be undetected in polarization due to unresolved polarization structure within our beam. We propose that disks with inclinations > 60 • are the best candidates for future polarization studies of dust selfscattering as these systems will generally show uniform polarization vectors that do not require very high resolution to resolve. We release the continuum and polarization images for all the sources with this publication. Data from the entire survey can be obtained from Dataverse. † Hubble Fellow

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“…However, no circumstellar gas emission in either cold or warm molecules has been detected to be associated with VLA 1623 B. In contrast, VLA 1623 B drives a fast and collimated jet and outflow (Santangelo et al 2015), and presents a variable H 2 O maser (Furuya et al 2003). The lack of detected circumstellar gas emission around VLA 1623 B is difficult to explain.…”

Section: Discussionmentioning

confidence: 99%

“…Cycle 2 observations in Bands 6 and 7 (Project code: 2013.0.01004; PI: S.-P. Lai) have a phase center of α J2000 = 16:26:26.390; δ J2000 = −24:24:30.688, and targeted several molecular lines (e.g., DCO + , CO isotopologues and c−C 3 H 2 in Band 6, DCO + , N 2 H + and H 2 D + in Band 7) along with continuum. The molecular line observations are detailed in Santangelo et al (2015); Murillo et al (2015Murillo et al ( , 2018. ALMA Cycle 0 Band 6 observations (Project code: 2011.0.00902.S; PI: N. Murillo) of VLA 1623, with phase center α J2000 = 16:26:26.419; δ J2000 = −24:24:29.988, slightly offset from the position of VLA 1623 A, were previously reported in .…”

Section: Observationsmentioning

confidence: 99%

“…VLA 1623 A is brightest in the submillimeter wavelength range, presenting a centrally peaked source with extended dust emission coinciding with the Keplerian disk traced in C 18 O . VLA 1623 B is separated from source A by 1.1 to the west, and presents a strongly collimated outflow (Santangelo et al 2015). Interferometric observations do not detect warm (C 18 O, c−C 3 H 2 ) or cold (DCO + , N 2 D + , N 2 H + ) gas emission associated with VLA 1623 B (Murillo et al , 2016.…”

Section: Introductionmentioning

confidence: 99%

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Revised SED of the triple protostellar system VLA 1623−2417

Murillo

Harsono

McClure

et al. 2018

A&A

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Context. VLA 1623−2417 is a triple protostellar system deeply embedded in Ophiuchus A. Sources A and B have a separation of 1.1 , making their study difficult beyond the submillimeter regime. Lack of circumstellar gas emission suggested that VLA 1623 B has a very cold envelope and is much younger than source A, generally considered the prototypical Class 0 source. Aims. We explore the consequences of new ALMA Band 9 data on the spectral energy distribution (SED) of VLA 1623−2417 and their inferred nature. Methods. Using dust continuum observations spanning from centimeter to near-infrared wavelengths, the SED of each component in VLA 1623−2417 is constructed and analysed. Results. The ALMA Band 9 data presented here show that the SED of VLA 1623−2417 B does not peak at 850µm as previously expected, but instead presents the same shape as VLA 1623−2417 A at wavelengths shorter than 450 µm. Conclusions. The results presented here indicate that the previous assumption that the flux in Herschel and Spitzer observations is solely dominated by VLA 1623−2417 A is not valid, and instead, VLA 1623−2417 B most likely contributes a significant fraction of the flux at λ < 450 µm. These results, however, do not explain the lack of circumstellar gas emission and puzzling nature of VLA 1623−2417 B.

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Disentangling the jet emission from protostellar systems

Cited by 25 publications

References 15 publications

A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores

A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores

Dust Polarization toward Embedded Protostars in Ophiuchus with ALMA. III. Survey Overview

Revised SED of the triple protostellar system VLA 1623−2417

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