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The Formation Conditions of the Wide Binary Class 0 Protostars within BHR 71
Astrophysics of Galaxies · Submitted 7 Nov 2018
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim We instead conclude that the binary system most likely formed via turbulent fragmentation of the core.
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The abstract, sentence by sentence
We present a characterization of the binary protostar system that is forming within a dense core in the isolated dark cloud BHR71. The pair of protostars, IRS1 and IRS2, are both in the Class 0 phase, determined from observations that resolve the sources from 1 um out to 250 um and from 1.3 mm to 1.3cm. The resolved observations enable the luminosities of IRS1 and IRS2 to be independently measured (14.7 and 1.7L_sun, respectively), in addition to the bolometric temperatures 68~K, and 38~K, respectively. The surrounding core was mapped in NH3 (1,1) with the Parkes radio telescope, and followed with higher-resolution observations from ATCA in NH3 (1,1) and 1.3cm continuum. The protostars were then further characterized with ALMA observations in the 1.3~mm continuum along with N2D+ (J=3-2), 12CO, 13CO, and C18O (J=2-1) molecular lines. The Parkes observations find evidence for a velocity gradient across the core surrounding the two protostars, while ATCA reveals more complex velocity structure toward the protostars within the large-scale gradient. The ALMA observations then reveal that the two protostars are at the same velocity in C18O, and N2H+ exhibits a similar velocity structure as NH3. However, the C18O kinematics reveal that the rotation on scales $<$1000~AU around IRS1 and IRS2 are in opposite directions. Taken with the lack of a systematic velocity difference between the pair, it is unlikely that their formation resulted from rotational fragmentation. We instead conclude that the binary system most likely formed via turbulent fragmentation of the core.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We present a characterization of the binary protostar system that is forming within a dense core in the isolated dark cloud BHR71. | contribution 1.00 | 0.88 | 0.03 | asserted 0.97 |
| s1 | The pair of protostars, IRS1 and IRS2, are both in the Class 0 phase, determined from observations that resolve the sources from 1 um out to 250 um and from 1.3 mm to 1.3cm. | result 0.83 | 0.89 | 0.02 | asserted 1.00 |
| s2 | The resolved observations enable the luminosities of IRS1 and IRS2 to be independently measured (14.7 and 1.7L_sun, respectively), in addition to the bolometric temperatures 68~K, and 38~K, respectively. | result 1.00 | 0.93 | 0.02 | asserted 1.00 |
| s3 | The surrounding core was mapped in NH3 (1,1) with the Parkes radio telescope, and followed with higher-resolution observations from ATCA in NH3 (1,1) and 1.3cm continuum. | method 1.00 | 0.89 | 0.01 | asserted 0.99 |
| s4 | The protostars were then further characterized with ALMA observations in the 1.3~mm continuum along with N2D+ (J=3-2), 12CO, 13CO, and C18O (J=2-1) molecular lines. | method 1.00 | 0.91 | 0.01 | asserted 0.99 |
| s5 | The Parkes observations find evidence for a velocity gradient across the core surrounding the two protostars, while ATCA reveals more complex velocity structure toward the protostars within the large-scale gradient. | result 1.00 | 0.94 | 0.02 | asserted 0.96 |
| s6 | The ALMA observations then reveal that the two protostars are at the same velocity in C18O, and N2H+ exhibits a similar velocity structure as NH3. | result 1.00 | 0.91 | 0.02 | asserted 1.00 |
| s7 | However, the C18O kinematics reveal that the rotation on scales $<$1000~AU around IRS1 and IRS2 are in opposite directions. | result 1.00 | 0.92 | 0.05 | asserted 1.00 |
| s8 | Taken with the lack of a systematic velocity difference between the pair, it is unlikely that their formation resulted from rotational fragmentation. | interpretation 1.00 | 0.81 | 0.10 | hedged possibility 0.93 |
| s9 | We instead conclude that the binary system most likely formed via turbulent fragmentation of the core. | interpretation 1.00 | 0.82 | 0.92 | hedged possibility 0.98 |
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The paper
Original abstract
We present a characterization of the binary protostar system that is forming within a dense core in the isolated dark cloud BHR71. The pair of protostars, IRS1 and IRS2, are both in the Class 0 phase, determined from observations that resolve the sources from 1 um out to 250 um and from 1.3 mm to 1.3cm. The resolved observations enable the luminosities of IRS1 and IRS2 to be independently measured (14.7 and 1.7L_sun, respectively), in addition to the bolometric temperatures 68~K, and 38~K, respectively. The surrounding core was mapped in NH3 (1,1) with the Parkes radio telescope, and followed with higher-resolution observations from ATCA in NH3 (1,1) and 1.3cm continuum. The protostars were then further characterized with ALMA observations in the 1.3~mm continuum along with N2D+ (J=3-2), 12CO, 13CO, and C18O (J=2-1) molecular lines. The Parkes observations find evidence for a velocity gradient across the core surrounding the two protostars, while ATCA reveals more complex velocity structure toward the protostars within the large-scale gradient. The ALMA observations then reveal that the two protostars are at the same velocity in C18O, and N2H+ exhibits a similar velocity structure as NH3. However, the C18O kinematics reveal that the rotation on scales $<$1000~AU around IRS1 and IRS2 are in opposite directions. Taken with the lack of a systematic velocity difference between the pair, it is unlikely that their formation resulted from rotational fragmentation. We instead conclude that the binary system most likely formed via turbulent fragmentation of the core.
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Papers whose main result relates to this one's
States a conflicting result 1 paper
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Based on the morphology and velocity structure, we suggest that the sub-cores in CG30 were formed by initial fragmentation of a filamentary prestellar core, while those in BHR71 could originate from rotational fragmentation of a single collapsing protostellar core.
ATCA and Spitzer Observations of the Binary Protostellar Systems CG30 and BHR71 · 0.94
What it cites · 1 sentence without a confident label
Uses the method or tool of 1 paper
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Astropy [ref] , APLpy [ref] , CASA [ref] , The IDL Astronomy User's Library (https://idlastro.gsfc.nasa.gov/)
The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package · Summary and Conclusions · 1.00
Cites as background 1 paper
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Recent work by [ref] explored fragmentation with rotating cloud cores including magnetic fields.
Collapse and Fragmentation of Magnetic Molecular Cloud Cores with the Enzo AMR MHD Code. II. Prolate and Oblate Cores · Formation of the Binary System · 0.84
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