Circumstellar disks of the most vigorously accreting young stars

Liu, Hauyu Baobab; Takami, M.; Kudo, Tomoyuki; Hashimoto, Jun; Dong, Ruobing; Vorobyov, Eduard I.; Pyo, Tae‐Soo; Fukagawa, Misato; Tamura, Motohide; Henning, Thomas; Dunham, Michael M.; Karr, J.; Kusakabe, Nobuhiko; Tsuribe, Toru

doi:10.1126/sciadv.1500875

Cited by 83 publications

(91 citation statements)

References 70 publications

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“…In near-infrared scattered-light imaging of disks, spiral arms have been found in both embedded Class 0/I objects surrounded by infalling envelopes (Canovas et al 2015;Liu et al 2016b) and revealed Class II objects (i.e., Herbig and T Tauri stars; Figure 1). While gravitational instability may drive the arms in Class 0/I disks (e.g., Vorobyov & Basu 2005, 2010Dong et al 2016b;Pérez et al 2016;Tobin et al 2016;Meru et al 2017;Tomida et al 2017), which tend to be massive and are fed by infall from the envelope, the origin of the arms detected in Class II disks is unclear.…”

Section: Sample Selection and Statisticsmentioning

confidence: 99%

Spiral Arms in Disks: Planets or Gravitational Instability?

Dong

Najita

Brittain

2018

ApJ

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Spiral arm structures seen in scattered-light observations of protoplanetary disks can potentially serve as signposts of planetary companions. They can also lend unique insights into disk masses, which are critical in setting the mass budget for planet formation but are difficult to determine directly. A surprisingly high fraction of disks that have been well studied in scattered light have spiral arms of some kind (8/29), as do a high fraction (6/11) of wellstudied Herbig intermediate-mass stars (i.e., Herbig stars >1.5 M e ). Here we explore the origin of spiral arms in Herbig systems by studying their occurrence rates, disk properties, and stellar accretion rates. We find that two-arm spirals are more common in disks surrounding Herbig intermediate-mass stars than are directly imaged giant planet companions to mature A and B stars. If two-arm spirals are produced by such giant planets, this discrepancy suggests that giant planets are much fainter than predicted by hot-start models. In addition, the high stellar accretion rates of Herbig stars, if sustained over a reasonable fraction of their lifetimes, suggest that disk masses are much larger than inferred from their submillimeter continuum emission. As a result, gravitational instability is a possible explanation for multiarm spirals. Future observations can lend insights into the issues raised here.

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Section: Sample Selection and Statisticsmentioning

confidence: 99%

Spiral Arms in Disks: Planets or Gravitational Instability?

Dong

Najita

Brittain

2018

ApJ

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“…On the other hand, the previous CO observations have shown that FU Orionis objects may be associated with extended gaseous disk (Kóspál 2011;Hales et al 2015). The high angular resolution near infrared coronagraphic polarization imaging of the previous Subaru-8.2m telescope observations further resolved spiral arm-like patterns and large-scale (>500 au) arcs on the disks of the four FU Orionis objects FU Ori, Z CMa, V1057 Cyg, and V1735 Cyg, which can be explained by the signatures of disk gravitational instability (Liu et al 2016b;Dong et al 2016). However, the CO and infrared emission are both optically thick in the observed regions, and therefore cannot provide good constraints on disk mass distributions.…”

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confidence: 84%

“…Figure 1 shows the SMA 224 GHz image and the JVLA 33 GHz image, which were generated utilizing the full bandwidth coverages of these observations (Section 2.1.1, 2.2.1). An overlay of the JVLA 33 GHz image with the previous Subaru High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO) 1.6 µm polarization intensity image (Liu et al 2016b) is presented in Figure 2. The 33 GHz image resolved two compact emission sources, which are immediately around FU Ori and a projectedly nearby source FU Ori S. They center at R.A. = 05 h 45 m 22 s .368 (J2000), decl.…”

Section: Ghzmentioning

confidence: 99%

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A concordant scenario to explain FU Orionis from deep centimeter and millimeter interferometric observations

Liu

Vorobyov

Dong

et al. 2017

A&A

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Aims. The aim of this work is to constrain properties of the disk around the archetype FU Orionis object, FU Ori, with as good as ∼25 au resolution. Methods. We resolved FU Ori at 29-37 GHz using the Karl G. Jansky Very Largy Array (JVLA) in the A-array configuration, which provided the highest possible angular resolution to date at this frequency band (∼0 ′′ .07). We also performed complementary JVLA 8-10 GHz observations, the Submillimeter Array (SMA) 224 GHz and 272 GHz observations, and compared with archival Atacama Large Millimeter Array (ALMA) 346 GHz observations to obtain the spectral energy distributions (SEDs). Results. Our 8-10 GHz observations do not find evidence for the presence of thermal radio jets, and constrain the radio jet/wind flux to at least 90 times lower than the expected value from the previously reported bolometric luminosity-radio luminosity correlation. The emission at frequencies higher than 29 GHz may be dominated by the two spatially unresolved sources, which are located immediately around FU Ori and its companion FU Ori S, respectively. Their deconvolved radii at 33 GHz are only a few au, which is two orders of magnitude smaller in linear scale than the gaseous disk revealed by the previous Subaru-HiCIAO 1.6 µm coronagraphic polarization imaging observations. We are struck by the fact that these two spatially compact sources contribute to over 50% of the observed fluxes at 224 GHz, 272 GHz, and 346 GHz. The 8-346 GHz SEDs of FU Ori and FU Ori S cannot be fit by constant spectral indices (over frequency), although we cannot rule out that it is due to the time variability of their (sub)millimeter fluxes. Conclusions. The more sophisticated models for SEDs considering the details of the observed spectral indices in the millimeter bands suggest that the >29 GHz emission is contributed by a combination of free-free emission from ionized gas, and thermal emission from optically thick and optically thin dust components. We hypothesize that dust in the innermost parts of the disks ( 0.1 au) has been sublimated, and thus the disks are no more well shielded against the ionizing photons. The estimated overall gas and dust mass based on SED modeling, can be as high as a fraction of a solar mass, which is adequate for developing disk gravitational instability. Our present explanation for the observational data is that the massive inflow of gas and dust due to disk gravitational instability or interaction with a companion/intruder, was piled up at the few au scale due to the development of a deadzone with negligible ionization. The piled up material subsequently triggered the thermal instability and the magnetorotational instability when the ionization fraction in the inner sub-au scale region exceeded a threshold value, leading to the high protostellar accretion rate.

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“…comm.). In Subaru/HiCIAO H-and K-band scattered-light imaging of four outbursting FU Ori disk systems, Liu et al (2016) displayed a linear feature on a scale of 1000 au at an odd angle with respect to the centre-radial direction (their Fig. 1).…”

Section: Observabilitymentioning

confidence: 99%

Spirals in protoplanetary disks from photon travel time

Kama

Pinilla

Heays

2016

A&A

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Spiral structures are a common feature in scattered-light images of protoplanetary disks, and of great interest as possible tracers of the presence of planets. However, other mechanisms have been put forward to explain them, including self-gravity, disk-envelope interactions, and dead zone boundaries. These mechanisms explain many spirals very well, but are unable to easily account for very loosely wound spirals and single spiral arms. We study the effect of light travel time on the shape of a shadow cast by a clump orbiting close (within ∼1 au) of the central star, where there can be significant orbital motion during the light travel time from the clump to the outer disk and then to the sky plane. This delay in light rays reaching the sky plane gives rise to a variety of spiral-and arc-shaped shadows, which we describe with a general fitting formula for a flared, inclined disk.

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Circumstellar disks of the most vigorously accreting young stars

Abstract: Subaru-HiCIAO observations on FU Orionis objects revealed asymmetric structures on 102 to 103 AU scales of circumstellar disks and envelopes.

Cited by 83 publications

References 70 publications

Spiral Arms in Disks: Planets or Gravitational Instability?

Spiral Arms in Disks: Planets or Gravitational Instability?

A concordant scenario to explain FU Orionis from deep centimeter and millimeter interferometric observations

Spirals in protoplanetary disks from photon travel time

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