Spiral structures in an embedded protostellar disk driven by envelope accretion

Lee, Chin-Fei; Li, Zhi-Yun; Turner, Neal

doi:10.1038/s41550-019-0905-x

Cited by 46 publications

(53 citation statements)

References 37 publications

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“…In addition, the present findings well resamble what found in the archetypical protostellar disk HH212, also close to be edge-on as IRAS04302 (e.g. Lee et al 2019, and references therein). Also in this case, a chemical enrichment in the gas phase associated with rotating rings is revealed by the V ∝ R kinematical feature (see e.g.…”

Section: H 2 Cs Kinematicssupporting

confidence: 88%

ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT)

Codella

Podio

Garufi

et al. 2020

A&A

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Context. Planet formation starts around Sun-like protostars with ages ≤ 1 Myr: what is the chemical compositions in disks? Aims. To trace the radial and vertical spatial distribution of H 2 CS, a key species of the S-bearing chemistry, in protoplanetary disks. To analyse the observed distributions in light of the H 2 CS binding energy, in order to discuss the role of thermal desorption in enriching the gas disk component. Methods. In the context of the ALMA chemical survey of Disk-Outflow sources in the Taurus star forming region (ALMA-DOT), we observed five Class I or early Class II sources with the o-H 2 CS(7 1,6 − 6 1,5) line. ALMA-Band 6 was used, reaching spatial resolutions 40 au, i.e. Solar System spatial scales. We also estimated the binding energy of H 2 CS using quantum mechanical calculations, for the first time, for an extended, periodic, crystalline ice. Results. We imaged H 2 CS emission in two rotating molecular rings in the HL Tau and IRAS04302+2247 disks. The outer radii are ∼ 140 au (HL Tau), and 115 au (IRAS 04302+2247). The edge-on geometry of IRAS 04302+2247 allows us to reveal that H 2 CS emission peaks, at radii of 60-115 au, at z = ± 50 au from the equatorial plane. Assuming LTE conditions, the column densities are ∼ 10 14 cm −2. Upper limits of a few 10 13 cm −2 have been estimated for the H 2 CS column densities in DG Tau, DG Tau B, and Haro 6-13 disks. For HL Tau, we derive, for the first time, the [H 2 CS]/[H] abundance in a protoplanetary disk (10 −14). The binding energy of H 2 CS computed for extended crystalline ice and amorphous ices is 4258 K and 3000-4600 K, respectively, implying a thermal evaporation where dust temperature is ≥ 50-80 K. Conclusions. H 2 CS traces the so-called warm molecular layer, a region previously sampled using CS, and H 2 CO. Thioformaldehyde peaks closer to the protostar than H 2 CO and CS, plausibly due to the relatively high-excitation level of observed 7 1,6 − 6 1,5 line (60 K). The H 2 CS binding energy implies that thermal desorption dominates in thin, au-sized, inner and/or upper disk layers, indicating that the observed H 2 CS emitting up to radii larger than 100 au is likely injected in the gas due to non-thermal processes.

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Section: H 2 Cs Kinematicssupporting

confidence: 88%

ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT)

Codella

Podio

Garufi

et al. 2020

A&A

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“…Therefore, it seems that the longest period of perturbations in the disks can come from the outer edge of the disk, probably induced by gravitational instability (GI) powered by envelope accretion. Such instability has been detected in the embedded Class I disk in HH 111, which shows a pair of spiral arms extending from the outer edge of the disk to the inner disk where the Toomre Q parameter is of the order of unity (Lee et al 2019b). An accretion shock is also detected around that disk in SO, indicative of an active accretion from the envelope (Lee et al 2016).…”

Section: Periodical Variations and Their Possible Originsmentioning

confidence: 88%

Molecular jets from low-mass young protostellar objects

Lee

2020

Astron Astrophys Rev

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Molecular jets are seen coming from the youngest protostars in the early phase of low-mass star formation. They are detected in CO, SiO, and SO at (sub)millimeter wavelengths down to the innermost regions, where their associated protostars and accretion disks are deeply embedded and where they are launched and collimated. They are not only the fossil records of accretion history of the protostars but also are expected to play an important role in facilitating the accretion process. Studying their physical properties (e.g., mass-loss rate, velocity, rotation, radius, wiggle, molecular content, shock formation, periodical variation, magnetic field, etc) allows us to probe not only the jet launching and collimation, but also the disk accretion and evolution, and potentially binary formation and planetary formation in the disks. Here, the recent exciting results obtained with high-spatial and high-velocity resolution observations of molecular jets in comparison to those obtained in the optical jets in the later phase of star formation are reviewed. Future observations of molecular jets with a large sample at high spatial and velocity resolution with ALMA are expected to lead to a breakthrough in our understanding of jets from young stars.

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“…Also, HOPS-140-B and HOPS-65 have large gaps in their disks (Appendix C; P. Sheehan et al 2020, in preparation), making the Gaussian fit very poor and overestimating the flux density and dust disk mass, such that these disks are not likely gravitationally unstable. Thus, after the removal of the likely false positives, the remaining the Class 0 systems HOPS-124, HH212mms, and HOPS-224 and the Class I systems HH111mms-A, HH270mms1-A, and HOPS-188 have distinctly disklike morphologies in the images shown in Appendix C. Furthermore, HH111mms-A has recently been found to have evidence of spiral structure in its disk (Lee et al 2020). Thus, these protostars are the most likely systems for which the disks may be self-gravitating, but we cannot rule out the possibility that others are self-gravitating (or that some of these are indeed non-self-gravitating) given our simple estimates of mass, radius, and temperature.…”

Section: Potential For Gravitationally Unstable Disksmentioning

confidence: 97%

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. II. A Statistical Characterization of Class 0 and Class I Protostellar Disks

Tobin

Sheehan

Megeath

et al. 2020

ApJ

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255

310

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We have conducted a survey of 328 protostars in the Orion molecular clouds with the Atacama Large Millimeter/ submillimeter Array at 0.87 mm at a resolution of ∼0 1 (40 au), including observations with the Very Large Array at 9mm toward 148 protostars at a resolution of ∼0 08 (32 au). This is the largest multiwavelength survey of protostars at this resolution by an order of magnitude. We use the dust continuum emission at 0.87 and 9mm to measure the dust disk radii and masses toward the Class 0, Class I, and flat-spectrum protostars, characterizing the evolution of these disk properties in the protostellar phase. The mean dust disk radii for the Class 0, Class I, and flat-spectrum protostars are -+ 44.9 3.4 5.8 , -+ 37.0 3.0 4.9 , and -+ 28.5 2.3 3.7 au, respectively, and the mean protostellar dust disk masses are 25.9 -+ 4.0 7.7 , -+ 14.9 2.2 3.8 , -+11.6 1.93.5 Å M , respectively. The decrease in dust disk masses is expected from disk evolution and accretion, but the decrease in disk radii may point to the initial conditions of star formation not leading to the systematic growth of disk radii or that radial drift is keeping the dust disk sizes small. At least 146 protostellar disks (35% of 379 detected 0.87 mm continuum sources plus 42 nondetections) have disk radii greater than 50 au in our sample. These properties are not found to vary significantly between different regions within Orion. The protostellar dust disk mass distributions are systematically larger than those of Class II disks by a factor of >4, providing evidence that the cores of giant planets may need to at least begin their formation during the protostellar phase.

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Spiral structures in an embedded protostellar disk driven by envelope accretion

Cited by 46 publications

References 37 publications

ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT)

ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT)

Molecular jets from low-mass young protostellar objects

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. II. A Statistical Characterization of Class 0 and Class I Protostellar Disks

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