Gas flow and accretion via spiral streamers and circumstellar disks in a young binary protostar

Alves, F. O.; Caselli, P.; Girart, J. M.; Segura-Cox, Dominique; Franco, G. A. P.; Schmiedeke, A.; Zhao, Bo

doi:10.1126/science.aaw3491

Cited by 88 publications

(90 citation statements)

References 28 publications

(62 reference statements)

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“…Further, given that at the scales of the observed circumstellar disks, dust scattering can decrease the intensity at millimeter wavelengths, which are likely also optically thick, our estimates for the mass of the compact sources should be taken as conservative lower limits (Liu 2019;Ueda et al 2020). The order of magnitude of the lower limits reported here is comparable to other compact (40 au) circumstellar disks in Class I multiple systems observed at high (25 au) resolution, derived in a similar fashion (Takakuwa et al 2017;Alves et al 2019;Cruz-Sáenz de Miera et al 2019).…”

Section: Masses From 3 MM Continuum Emissionsupporting

confidence: 66%

Orbital and Mass Constraints of the Young Binary System IRAS 16293-2422 A

Maureira

Pineda

Segura-Cox

et al. 2020

ApJ

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We present 3 mm ALMA continuum and line observations at resolutions of 6.5 au and 13 au, respectively, toward the Class 0 system IRAS 16293-2422 A. The continuum observations reveal two compact sources toward IRAS 16293-2422 A, coinciding with compact ionized gas emission previously observed at radio wavelengths (A1 and A2), confirming the long-known radio sources as protostellar. The emission toward A2 is resolved and traces a dust disk with an FWHM size of ∼12 au, while the emission toward A1 sets a limit to the FWHM size of the dust disk of ∼4 au. We also detect spatially resolved molecular kinematic tracers near the protostellar disks. Several lines of the J=5−4 rotational transition of HNCO, NH 2 CHO, and t-HCOOH are detected, with which we derived individual line-of-sight velocities. Using these together with the CS (J=2−1), we fit Keplerian profiles toward the individual compact sources and derive masses of the central protostars. The kinematic analysis indicates that A1 and A2 are a bound binary system. Using this new context for the previous 30 yr of Very Large Array observations, we fit orbital parameters to the relative motion between A1 and A2 and find that the combined protostellar mass derived from the orbit is consistent with the masses derived from the gas kinematics. Both estimations indicate masses consistently higher (0.5M 1 M 2  2 M  ) than previous estimations using lowerresolution observations of the gas kinematics. The ALMA high-resolution data provides a unique insight into the gas kinematics and masses of a young deeply embedded bound binary system.

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Section: Masses From 3 MM Continuum Emissionsupporting

confidence: 66%

Orbital and Mass Constraints of the Young Binary System IRAS 16293-2422 A

Maureira

Pineda

Segura-Cox

et al. 2020

ApJ

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“…This is important for observations because when planets are discovered orbiting a star with a distant stellar companion, the binary period and eccentricity are often unknown (e.g., K2-288b (Feinstein et al 2019)), but the planetary semimajor axis and/or the projected binary semimajor axis can be determined (see Table 5 for a list of known planet hosting binary stars). Moreover, observations of young binary stars can reveal the stability limit through dust and gas emission around either star (e.g., Alves et al 2019), but this is also a projected distance.…”

Section: Population Studiesmentioning

confidence: 99%

Orbital Stability of Circumstellar Planets in Binary Systems

Quarles

Kostov

et al. 2020

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Planets that orbit only one of the stars in stellar binary systems (i.e., circumstellar) are dynamically constrained to a limited range of orbital parameters and thus understanding conditions on their stability is of great importance in exoplanet searches. We perform ∼700 million N-body simulations to identify how stability regions depend on properties of the binary, as well as, the starting planetary inclination and mean longitude relative to the binary orbit. Moreover, we provide grid interpolation maps and lookup tables for the community to use our results. Through Monte-Carlo methods we determine that planets with a semimajor axis a p 8% of the binary semimajor axis a bin will likely be stable given the known distribution of binary star parameters. This estimate varies in the Lidov-Kozai regime or for retrograde orbits to 4% or 10% of a bin , respectively. Our method to quickly determine the circumstellar stability limit is important for interpreting observations of binaries using direct imaging with JWST, photometry with TESS, or even astrometry with Gaia.

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“…It is conceivable that these sharp, filamentary features are the result of grains aligned in accretion streamers; see Alves et al (2019) for the highest-resolution observations to date of accretion streamers that are funneling material onto the central sources in a low-mass protostellar binary. Theoretical work by Lazarian & Hoang (2007b) and Hoang et al (2018) on grain alignment via mechanical alignment torques (MATs) has suggested that helical grains could Figure 7.…”

Section: 4mentioning

confidence: 99%

Understanding the Origin of the Magnetic Field Morphology in the Wide-binary Protostellar System BHR 71

Hull

Gouellec

Girart

et al. 2020

ApJ

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We present 1.3 mm ALMA observations of polarized dust emission toward the wide-binary protostellar system BHR 71 IRS1 and IRS2. IRS1 features what appears to be a natal, hourglass-shaped magnetic field. In contrast, IRS2 exhibits a magnetic field that has been affected by its bipolar outflow. Toward IRS2, the polarization is confined mainly to the outflow cavity walls. Along the northern edge of the redshifted outflow cavity of IRS2, the polarized emission is sandwiched between the outflow and a filament of cold, dense gas traced by N 2 D + , toward which no dust polarization is detected. This suggests that the origin of the enhanced polarization in IRS2 is the irradiation of the outflow cavity walls, which enables the alignment of dust grains with respect to the magnetic field-but only to a depth of ∼ 300 au, beyond which the dust is cold and unpolarized. However, in order to align grains deep enough in the cavity walls, and to produce the high polarization fraction seen in IRS2, the aligning photons are likely to be in the mid-to far-infrared range, which suggests a degree of grain growth beyond what is typically expected in very young, Class 0 sources. Finally, toward IRS1 we see a narrow, linear feature with a high (10-20%) polarization fraction and a well ordered magnetic field that is not associated with the bipolar outflow cavity. We speculate that this feature may be a magnetized accretion streamer; however, this has yet to be confirmed by kinematic observations of dense-gas tracers. T19 discussed the formation conditions of BHR 71 at length, using both new and archival data to analyze the kinematics and continuum properties across a wide range of spatial scales ranging from ∼ 0.5 pc -80 au. They presented J-band near-infrared (NIR) observations from the

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Gas flow and accretion via spiral streamers and circumstellar disks in a young binary protostar

Cited by 88 publications

References 28 publications

Orbital and Mass Constraints of the Young Binary System IRAS 16293-2422 A

Orbital and Mass Constraints of the Young Binary System IRAS 16293-2422 A

Orbital Stability of Circumstellar Planets in Binary Systems

Understanding the Origin of the Magnetic Field Morphology in the Wide-binary Protostellar System BHR 71

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