Protostar L1455 Irs1: A Rotating Disk Connecting to a Filamentary Network

Chou, H.-G. J.; Yen, Hsi-Wei; Koch, Patrick M.; Guilloteau, S.

doi:10.3847/0004-637x/823/2/151

Cited by 11 publications

(8 citation statements)

References 75 publications

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“…The two Class 0 protostars IRAS16253 and IRAS15398 have been observed with ALMA by Yen et al (2017), who found a candidate disk radius of 20 au in IRAS15398 and an upper-limit disk radius of 6 au in IRAS16253. The Class 0 L1455 IRS1 was observed with the SMA, and the size of its protostellar disk was constrained to < 200 AU (Chou et al 2016). The HH211 Class 0 protostar was observed with ALMA, and its disk radius was constrained to < ∼ 10 au .…”

Section: Comparison With Other Workmentioning

confidence: 99%

Characterizing young protostellar disks with the CALYPSO IRAM-PdBI survey: large Class 0 disks are rare

Maury

André

Testi

et al. 2019

A&A

149

246

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Context. Understanding the formation mechanisms of protoplanetary disks and multiple systems and also their pristine properties are key questions for modern astrophysics. The properties of the youngest disks, embedded in rotating infalling protostellar envelopes, have largely remained unconstrained up to now. Aims. We aim to observe the youngest protostars with a spatial resolution that is high enough to resolve and characterize the progenitors of protoplanetary disks. This can only be achieved using submillimeter and millimeter interferometric facilities. In the framework of the IRAM Plateau de Bure Interferometer survey CALYPSO, we have obtained subarcsecond observations of the dust continuum emission at 231 GHz and 94 GHz for a sample of 16 solar-type Class 0 protostars. Methods. In an attempt to identify disk-like structures embedded at small scales in the protostellar envelopes, we modeled the dust continuum emission visibility profiles using Plummer-like envelope models and envelope models that include additional Gaussian disk-like components.Results. Our analysis shows that in the CALYPSO sample, 11 of the 16 Class 0 protostars are better reproduced by models including a disk-like dust continuum component contributing to the flux at small scales, but less than 25% of these candidate protostellar disks are resolved at radii > 60 au. Including all available literature constraints on Class 0 disks at subarcsecond scales, we show that our results are representative: most (> 72% in a sample of 26 protostars) Class 0 protostellar disks are small and emerge only at radii < 60 au. We find a multiplicity fraction of the CALYPSO protostars < ∼ 57% ± 10% at the scales 100-5000 au, which generally agrees with the multiplicity properties of Class I protostars at similar scales. Conclusions. We compare our observational constraints on the disk size distribution in Class 0 protostars to the typical disk properties from protostellar formation models. If Class 0 protostars contain similar rotational energy as is currently estimated for prestellar cores, then hydrodynamical models of protostellar collapse systematically predict a high occurrence of large disks. Our observations suggest that these are rarely observed, however. Because they reduce the centrifugal radius and produce a disk size distribution that peaks at radii < 100 au during the main accretion phase, magnetized models of rotating protostellar collapse are favored by our observations.

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Section: Comparison With Other Workmentioning

confidence: 99%

Characterizing young protostellar disks with the CALYPSO IRAM-PdBI survey: large Class 0 disks are rare

Maury

André

Testi

et al. 2019

A&A

149

246

View full text Add to dashboard Cite

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“…With recent interferometric observations at (sub-)millimeter wavelengths, Keplerian disks with radii of tens to hundreds of au have been detected around several embedded Class 0 and I protostars (Lommen et al 2008;Takakuwa et al 2012;Tobin et al 2012;Brinch & Jørgensen 2013;Murillo et al 2013;Ohashi et al 2014;Chou et al 2014;Harsono et al 2014;Lindberg et al 2014;Lee et al 2014Lee et al , 2016Yen et al 2014Yen et al , 2017Aso et al 2015;Chou et al 2016). On the other hand, there is a group of Class 0 protostars with envelope rotations on a 1000 au scale that are one order of magnitude slower than other Class 0 protostars (Brinch et al 2009;Yen et al 2010Yen et al , 2015aMaret et al 2014), and they do not exhibit Keplerian disks with sizes larger than 10-20 au (Maury et al 2010;Oya et al 2014;Yen et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Constraint on ion–neutral drift velocity in the Class 0 protostar B335 from ALMA observations

Yen

Zhao

Koch

et al. 2018

A&A

Self Cite

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Aims. Ambipolar diffusion can cause a velocity drift between ions and neutrals. This is one of the non-ideal magnetohydrodynamcis (MHD) effects proposed to enable the formation of large-scale Keplerian disks with sizes of tens of au. To observationally study ambipolar diffusion in collapsing protostellar envelopes, we compare here gas kinematics traced by ionized and neutral molecular lines and discuss the implication on ambipolar diffusion. Methods. We analyzed the data of the H 13 CO + (3-2) and C 18 O (2-1) emission in the Class 0 protostar B335 obtained with our ALMA observations. We constructed kinematical models to fit the velocity structures observed in the H 13 CO + and C 18 O emission and to measure the infalling velocities of the ionized and neutral gas on a 100 au scale in B335. Results. A central compact (∼1 ′′ -2 ′′ ) component that is elongated perpendicular to the outflow direction and exhibits a clear velocity gradient along the outflow direction is observed in both lines and most likely traces the infalling flattened envelope. With our kinematical models, the infalling velocities in the H 13 CO + and C 18 O emission are both measured to be 0.85±0.2 km s −1 at a radius of 100 au, suggesting that the velocity drift between the ionized and neutral gas is at most 0.3 km s −1 at a radius of 100 au in B335. Conclusions. The Hall parameter for H 13 CO + is estimated to be ≫1 on a 100 au scale in B335, so that H 13 CO + is expected to be attached to the magnetic field. Our non-detection or upper limit of the velocity drift between the ionized and neutral gas could suggest that the magnetic field remains rather well coupled to the bulk neutral material on a 100 au scale in this source, and that any significant field-matter decoupling, if present, likely occurs only on a smaller scale, leading to an accumulation of magnetic flux and thus efficient magnetic braking in the inner envelope. This result is consistent with the expectation from the MHD simulations with a typical ambipolar diffusivity and those without ambipolar diffusion. On the other hand, the high ambipolar drift velocity of 0.5-1.0 km s −1 on a 100 au scale predicted in the MHD simulations with an enhanced ambipolar diffusivity by removing small dust grains, where the minimum grain size is 0.1 µm, is not detected in our observations. However, because of our limited angular resolution, we cannot rule out a significant ambipolar drift only in the midplane of the infalling envelope. Future observations with higher angular resolutions (∼0 ′′ .1) are needed to examine this possibility and ambipolar diffusion on a smaller scale.

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“…This protostar is one of the brightest Class I sources in the L1455 region with a bolometric luminosity of 3.6 L (Dunham et al 2013). Goldsmith et al (1984) and Chou et al (2016) showed that the source is associated with a Keplerian disk (r < 200 au) and drives an high velocity outflow mapped in CO and C 18 O out to distances of ∼ 6000 au. This source is also associated with three knots detected in H 2 lines at near-infrared wavelengths (Davis et al 1997), which are located symmetrically with respect to the driving source in agreement with the collimated outflow structure imaged by Curtis et al (2010).…”

Section: L1455-irs1mentioning

confidence: 93%

Chemical survey of Class I protostars with the IRAM-30m

Mercimek,

Codella,

Podio

et al. 2021

Preprint

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Context. Class I protostars are a bridge between Class 0 protostars (≤ 10 5 yr old), and Class II (≥ 10 6 yr) protoplanetary disks. Recent studies show gaps and rings in the dust distribution of disks younger than 1 Myr, suggesting that planet formation may start already at the Class I stage. To understand what chemistry planets will inherit, it is crucial to characterize the chemistry of Class I sources and to investigate how chemical complexity evolves from Class 0 protostars to protoplanetary disks. Aims. The goal is twofold: (i) to obtain a census of the molecular complexity in a sample of four Class I protostars, and (ii) to compare it with the chemical compositions of earlier and later phases of the Sun-like star formation process. Methods. We performed IRAM-30 m observations at 1.3 mm towards 4 Class I objects (L1489-IRS, B5-IRS1, L1455-IRS1, and L1551-IRS5). The column densities of the detected species are derived assuming Local Thermodynamic Equilibrium (LTE) or Large Velocity Gradient (LVG). Results. We detected 27 species: C-chains, N-bearing species, S-bearing species, Si-bearing species, deuterated molecules, and interstellar Complex Organic Molecules (iCOMs; CH 3 OH, CH 3 CN, CH 3 CHO, and HCOOCH 3 ). Among the observed sample, L1551-IRS5 is the most chemically rich source. Different spectral profiles are observed: (i) narrow (∼1 km s −1 ) lines towards all the sources, (ii) broader (∼4 km s −1 ) lines towards L1551-IRS5, and (iii) line wings due to outflows (in B5-IRS1, L1455-IRS1, and L1551-IRS5). Narrow c-C 3 H 2 emission originates from the envelope with temperatures of 5 -25 K and sizes of ∼ 2 − 10 . The iCOMs in L1551-IRS5 reveal the occurrence of hot corino chemistry, with CH 3 OH and CH 3 CN lines originating from a compact (∼ 0 . 15) and warm (T > 50 K) region. Finally, OCS and H 2 S seem to probe the circumbinary disks in the L1455-IRS1 and L1551-IRS5 binary systems. The deuteration in terms of elemental D/H in the molecular envelopes is: ∼ 10 − 70% (D 2 CO/H 2 CO), ∼ 5 − 15% (HDCS/H 2 CS), and ∼ 1 − 23% (CH 2 DOH/CH 3 OH). For the L1551-IRS5 hot corino, we derive D/H ∼ 2% (CH 2 DOH/CH 3 OH). Conclusions. Carbon chain chemistry in extended envelopes is revealed towards all the sources. In addition, B5-IRS1, L1455-IRS1 and L1551-IRS5 show a low excitation methanol line which is narrow and centered at systemic velocity, suggesting an origin from an extended structure, plausibly UV illuminated. The abundance ratios of CH 3 CN, CH 3 CHO, and HCOOCH 3 with respect CH 3 OH measured towards the L1551-IRS5 hot corino are comparable to that estimated at earlier stages (prestellar cores, Class 0 protostars), as well as to that found in comets. The deuteration in our sample is also consistent with the values estimated for sources at earlier stages. These findings support the inheritance scenario from prestellar cores to the Class I phase when planets start forming.

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Protostar L1455 Irs1: A Rotating Disk Connecting to a Filamentary Network

Cited by 11 publications

References 75 publications

Characterizing young protostellar disks with the CALYPSO IRAM-PdBI survey: large Class 0 disks are rare

Characterizing young protostellar disks with the CALYPSO IRAM-PdBI survey: large Class 0 disks are rare

Constraint on ion–neutral drift velocity in the Class 0 protostar B335 from ALMA observations

Chemical survey of Class I protostars with the IRAM-30m

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