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A massive Keplerian protostellar disk with flyby-induced spirals in the Central Molecular Zone

Abstract

Accretion disks are an essential component in the paradigm of the formation of low-mass stars. Recent observations further identify disks surrounding low-mass pre-main-sequence stars perturbed by flybys. Whether disks around more massive stars evolve in a similar manner has become an urgent question. We report the discovery of a Keplerian disk of a few solar masses surrounding a 32 M protostar in the Sagittarius C cloud around the Galactic Centre. The disk is gravitationally stable with two embedded spirals. A combined analysis of analytical solutions and numerical simulations demonstrates that the most likely scenario to form the spirals is through external perturbations induced by a close flyby, and one such perturber with the expected parameters is identified. The massive, early O-type star embedded in this disk forms in a similar manner as do low-mass stars, in the sense of not only disk-mediated accretion, but also flyby-impacted disk evolution.

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Fig. 1: Disk properties and configurations on the basis of ALMA band 6 (1.3 mm) observations.
Fig. 2: Disk-to-protostar mass ratios versus protostar masses for spatially resolved massive protostellar disks with substructures.
Fig. 3: Parameter space of perturbation-induced structure formation.
Fig. 4: Comparison between the observed environment of the disk and the simulated system after a flyby event.

Data availability

This paper makes use of the following ALMA data: ADS/JAO.ALMA#2018.1.00641.S. The data are available at https://almascience.nao.ac.jp/aq by setting the observation code. The reduced data used for this study are available from the corresponding authors upon reasonable request.

Code availability

The ALMA data were reduced using CASA versions 5.4.0 and 5.6.1, which are available at https://casa.nrao.edu/casa_obtaining.shtml. The code to make Fig. 3 is available at https://doi.org/10.5281/zenodo.6413326. The 3DBarolo code is available at https://github.com/editeodoro/Bbarolo. The Phantom code is available at https://github.com/danieljprice/phantom. The splash code is available at https://github.com/danieljprice/splash.

References

  1. Longmore, S. N. et al. Variations in the Galactic star formation rate and density thresholds for star formation. Mon. Not. R. Astron. Soc. 429, 987–1000 (2013).

    Article  ADS  Google Scholar 

  2. Barnes, A. T. et al. Star formation rates and efficiencies in the Galactic Centre. Mon. Not. R. Astron. Soc. 469, 2263–2285 (2017).

    Article  ADS  Google Scholar 

  3. Kauffmann, J. et al. The Galactic Center Molecular Cloud Survey. I. A steep linewidth–size relation and suppression of star formation. Astron. Astrophys. 603, A89 (2017).

    Article  Google Scholar 

  4. Lu, X. et al. A census of early-phase high-mass star formation in the Central Molecular Zone. Astrophys. J. Suppl. 244, 35 (2019).

    Article  ADS  Google Scholar 

  5. Lu, X. et al. ALMA observations of massive clouds in the Central Molecular Zone: ubiquitous protostellar outflows. Astrophys. J. 909, 177 (2021).

    Article  ADS  Google Scholar 

  6. Walker, D. L. et al. Star formation in ‘the Brick’: ALMA reveals an active protocluster in the Galactic centre cloud G0.253+0.016. Mon. Not. R. Astron. Soc. 503, 77–95 (2021).

    Article  ADS  Google Scholar 

  7. Reid, M. J. et al. Trigonometric parallaxes of high-mass star-forming regions: our view of the Milky Way. Astrophys. J. 885, 131 (2019).

    Article  ADS  Google Scholar 

  8. Beltrán, M. T. & de Wit, W. J. Accretion disks in luminous young stellar objects. Astron. Astrophys. Rev. 24, 6 (2016).

    Article  ADS  Google Scholar 

  9. Zhao, B. et al. Formation and evolution of disks around young stellar objects. Space Sci. Rev. 216, 43 (2020).

    Article  ADS  Google Scholar 

  10. Johnston, K. G. et al. A Keplerian-like disk around the forming O-type star AFGL 4176. Astrophys. J. Lett. 813, L19 (2015).

    Article  ADS  Google Scholar 

  11. Sanna, A. et al. Discovery of a sub-Keplerian disk with jet around a 20 M young star. ALMA observations of G023.01-00.41. Astron. Astrophys. 623, A77 (2019).

    Article  Google Scholar 

  12. Maud, L. T. et al. Substructures in the Keplerian disc around the O-type (proto-)star G17.64+0.16. Astron. Astrophys. 627, L6 (2019).

    Article  ADS  Google Scholar 

  13. Motogi, K. et al. The first bird’s-eye view of a gravitationally unstable accretion disk in high-mass star formation. Astrophys. J. Lett. 877, L25 (2019).

    Article  ADS  Google Scholar 

  14. Zapata, L. A. et al. An asymmetric Keplerian disk surrounding the O-type protostar IRAS 16547-4247. Astrophys. J. 872, 176 (2019).

    Article  ADS  Google Scholar 

  15. Johnston, K. G. et al. Spiral arms and instability within the AFGL 4176 mm1 disc. Astron. Astrophys. 634, L11 (2020).

    Article  ADS  Google Scholar 

  16. Sanna, A. et al. Physical conditions in the warped accretion disk of a massive star. 349 GHz ALMA observations of G023.01-00.41. Astron. Astrophys. 655, A72 (2021).

    Article  Google Scholar 

  17. Shu, F. H., Adams, F. C. & Lizano, S. Star formation in molecular clouds: observation and theory. Annu. Rev. Astron. Astrophys. 25, 23–81 (1987).

    Article  ADS  Google Scholar 

  18. Cesaroni, R. et al. Chasing discs around O-type (proto)stars: evidence from ALMA observations. Astron. Astrophys. 602, A59 (2017).

    Article  Google Scholar 

  19. Toomre, A. On the gravitational stability of a disk of stars. Astrophys. J. 139, 1217–1238 (1964).

    Article  ADS  Google Scholar 

  20. Durisen, R. H. et al. in Protostars and Planets V (eds Reipurth, B. et al.) 607 (Univ. Arizona Press, 2007).

  21. Clarke, C. J. & Pringle, J. E. Accretion disc response to a stellar fly-by. Mon. Not. R. Astron. Soc. 261, 190–202 (1993).

    Article  ADS  Google Scholar 

  22. Pfalzner, S. Spiral arms in accretion disk encounters. Astrophys. J. 592, 986–1001 (2003).

    Article  ADS  Google Scholar 

  23. Bate, M. R., Bonnell, I. A. & Bromm, V. The formation of a star cluster: predicting the properties of stars and brown dwarfs. Mon. Not. R. Astron. Soc. 339, 577–599 (2003).

    Article  ADS  Google Scholar 

  24. Xiang-Gruess, M. Generation of highly inclined protoplanetary discs through single stellar flybys. Mon. Not. R. Astron. Soc. 455, 3086–3100 (2016).

    Article  ADS  Google Scholar 

  25. Vincke, K. & Pfalzner, S. Cluster dynamics largely shapes protoplanetary disk sizes. Astrophys. J. 828, 48 (2016).

    Article  ADS  Google Scholar 

  26. Winter, A. J. et al. Protoplanetary disc truncation mechanisms in stellar clusters: comparing external photoevaporation and tidal encounters. Mon. Not. R. Astron. Soc. 478, 2700–2722 (2018).

    Article  ADS  Google Scholar 

  27. Cuello, N. et al. Flybys in protoplanetary discs: I. Gas and dust dynamics. Mon. Not. R. Astron. Soc. 483, 4114–4139 (2019).

    Article  ADS  Google Scholar 

  28. Cabrit, S., Pety, J., Pesenti, N. & Dougados, C. Tidal stripping and disk kinematics in the RW Aurigae system. Astron. Astrophys. 452, 897–906 (2006).

    Article  ADS  Google Scholar 

  29. Dai, F., Facchini, S., Clarke, C. J. & Haworth, T. J. A tidal encounter caught in the act: modelling a star–disc fly-by in the young RW Aurigae system. Mon. Not. R. Astron. Soc. 449, 1996–2009 (2015).

    Article  ADS  Google Scholar 

  30. Kurtovic, N. T. et al. The Disk Substructures at High Angular Resolution Project (DSHARP). IV. Characterizing substructures and interactions in disks around multiple star systems. Astrophys. J. Lett. 869, L44 (2018).

    Article  ADS  Google Scholar 

  31. Rodriguez, J. E. et al. Multiple stellar flybys sculpting the circumstellar architecture in RW Aurigae. Astrophys. J. 859, 150 (2018).

    Article  ADS  Google Scholar 

  32. Akiyama, E. et al. A tail structure associated with a protoplanetary disk around SU Aurigae. Astron. J. 157, 165 (2019).

    Article  ADS  Google Scholar 

  33. Pérez, S. et al. Resolving the FU Orionis system with ALMA: interacting twin disks? Astrophys. J. 889, 59 (2020).

    Article  ADS  Google Scholar 

  34. Ménard, F. et al. Ongoing flyby in the young multiple system UX Tauri. Astron. Astrophys. 639, L1 (2020).

    Article  ADS  Google Scholar 

  35. Zapata, L. A. et al. Tidal interaction between the UX Tauri A/C disk system revealed by ALMA. Astrophys. J. 896, 132 (2020).

    Article  ADS  Google Scholar 

  36. Dong, R. et al. A likely flyby of binary protostar Z CMa caught in action. Nat. Astron. 6, 331–338 (2022).

  37. Chambers, E. T., Yusef-Zadeh, F. & Roberts, D. Methanol maser emission from Galactic Center sources with excess 4.5 μm emission. Astrophys. J. 733, 42 (2011).

    Article  ADS  Google Scholar 

  38. Kendrew, S. et al. Early-stage massive star formation near the Galactic Center: Sgr C. Astrophys. J. Lett. 775, L50 (2013).

    Article  ADS  Google Scholar 

  39. Lu, X. et al. Star formation rates of massive molecular clouds in the Central Molecular Zone. Astrophys. J. 872, 171 (2019).

    Article  ADS  Google Scholar 

  40. Borchert, E. M. A., Price, D. J., Pinte, C. & Cuello, N. On the rise times in FU Orionis events. Mon. Not. R. Astron. Soc. 510, L37–L41 (2022).

    Article  ADS  Google Scholar 

  41. Tobin, J. J. et al. A triple protostar system formed via fragmentation of a gravitationally unstable disk. Nature 538, 483–486 (2016).

    Article  ADS  Google Scholar 

  42. Kruijssen, J. M. D., Dale, J. E. & Longmore, S. N. The dynamical evolution of molecular clouds near the Galactic Centre—I. Orbital structure and evolutionary timeline. Mon. Not. R. Astron. Soc. 447, 1059–1079 (2015).

    Article  ADS  Google Scholar 

  43. Molinari, S. et al. A 100 pc elliptical and twisted ring of cold and dense molecular clouds revealed by Herschel around the Galactic Center. Astrophys. J. Lett. 735, L33 (2011).

    Article  ADS  Google Scholar 

  44. Möller, T., Endres, C. & Schilke, P. eXtended CASA Line Analysis Software Suite (XCLASS). Astron. Astrophys. 598, A7 (2017).

    Article  ADS  Google Scholar 

  45. Panagia, N. Some physical parameters of early-type stars. Astron. J. 78, 929–934 (1973).

    Article  ADS  Google Scholar 

  46. Scoville, N. Z. & Kwan, J. Infrared sources in molecular clouds. Astrophys. J. 206, 718–727 (1976).

    Article  ADS  Google Scholar 

  47. Garay, G. & Lizano, S. Massive stars: their environment and formation. Publ. Astron. Soc. Pac. 111, 1049–1087 (1999).

    Article  ADS  Google Scholar 

  48. Di Teodoro, E. M. & Fraternali, F. 3DBAROLO: a new 3D algorithm to derive rotation curves of galaxies. Mon. Not. R. Astron. Soc. 451, 3021–3033 (2015).

    Article  ADS  Google Scholar 

  49. Ossenkopf, V. & Henning, T. Dust opacities for protostellar cores. Astron. Astrophys. 291, 943–959 (1994).

    ADS  Google Scholar 

  50. D’Onghia, E., Vogelsberger, M., Faucher-Giguere, C.-A. & Hernquist, L. Quasi-resonant theory of tidal interactions. Astrophys. J. 725, 353–368 (2010).

    Article  ADS  Google Scholar 

  51. Price, D. J. et al. Phantom: a smoothed particle hydrodynamics and magnetohydrodynamics code for astrophysics. Publ. Astron. Soc. Aust. 35, e031 (2018).

    Article  ADS  Google Scholar 

  52. Breslau, A., Steinhausen, M., Vincke, K. & Pfalzner, S. Sizes of protoplanetary discs after star–disc encounters. Astron. Astrophys. 565, A130 (2014).

    Article  ADS  Google Scholar 

  53. Bhandare, A., Breslau, A. & Pfalzner, S. Effects of inclined star–disk encounter on protoplanetary disk size. Astron. Astrophys. 594, A53 (2016).

    Article  ADS  Google Scholar 

  54. Price, D. J. splash: an interactive visualisation tool for smoothed particle hydrodynamics simulations. Publ. Astron. Soc. Aust. 24, 159–173 (2007).

    Article  ADS  Google Scholar 

  55. Cuello, N. et al. Flybys in protoplanetary discs—II. Observational signatures. Mon. Not. R. Astron. Soc. 491, 504–514 (2020).

    Article  ADS  Google Scholar 

  56. Davies, M. B. in The Astrophysics of Planetary Systems: Formation, Structure, and Dynamical Evolution Vol. 276 (eds Sozzetti, A. et al.) 304–307 (Cambridge Univ. Press, 2011).

  57. Pfalzner, S. Early evolution of the birth cluster of the Solar System. Astron. Astrophys. 549, A82 (2013).

    Article  ADS  Google Scholar 

  58. Otter, J. et al. Small protoplanetary disks in the Orion Nebula Cluster and OMC1 with ALMA. Astrophys. J. 923, 221 (2021).

    Article  ADS  Google Scholar 

  59. Ginsburg, A. & Kruijssen, J. M. D. A high cluster formation efficiency in the Sagittarius B2 complex. Astrophys. J. Lett. 864, L17 (2018).

    Article  ADS  Google Scholar 

  60. Andrews, S. M., Rosenfeld, K. A., Kraus, A. L. & Wilner, D. J. The mass dependence between protoplanetary disks and their stellar hosts. Astrophys. J. 771, 129 (2013).

    Article  ADS  Google Scholar 

  61. Garufi, A. et al. Evolution of protoplanetary disks from their taxonomy in scattered light: spirals, rings, cavities, and shadows. Astron. Astrophys. 620, A94 (2018).

    Article  Google Scholar 

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Acknowledgements

We thank H. B. Liu, Y. Cheng and P. Sanhueza for helpful discussions. X.L. acknowledges support from the Initial Funding of Scientific Research for High-Level Talents at Shanghai Astronomical Observatory, and the Japan Society for the Promotion of Science KAKENHI grant 20K14528. G.-X.L. thanks M. Krause for discussions on the flyby scenario. G.-X.L. acknowledges support from NSFC grants W820301904 and 12033005. This work made use of the High Performance Computing Resource in the Core Facility for Advanced Research Computing at Shanghai Astronomical Observatory, and the Multi-wavelength Data Analysis System operated by the Astronomy Data Center, National Astronomical Observatory of Japan. It made use of the following ALMA data: ADS/JAO.ALMA#2018.1.00641.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

Author information

Authors and Affiliations

Authors

Contributions

X.L. led the ALMA proposal, data reduction, numerical simulation and paper writing. G.-X.L. led the interpretation of the data and analytical solutions, and contributed to numerical simulation and paper writing. Q.Z. commented on and helped to improve the article and the observing proposal. Y.L. contributed to the estimate of gas temperatures and commented on the article.

Corresponding authors

Correspondence to Xing Lu or Guang-Xing Li.

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The authors declare no competing interests.

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Nature Astronomy thanks Susanne Pfalzner, Nicolas Cuello and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Broader environment of the disk.

Left: the velocity field of the disk and the two condensations, derived from the CH3OCHO line. The blue and red contours show the blue and red-shifted SiO emission from previous ALMA observations5. The blue-shifted SiO emission is integrated between − 80 and − 51 kms−1, and the red-shifted SiO emission between − 48 and − 25 km s−1. The bipolar outflow associated with the disk, which has been identified in Ref. 5 using multiple molecular lines including SiO, is marked by the blue and red arrows. The best-fit kinematic major axis of the disk is denoted by the green dashed line, same as in Fig. 1b. A candidate bipolar outflow associated with condensation A is marked by the dashed blue and red arrows. Right: the radio continuum emission in this region observed by the Very Large Array (VLA). Green contours are the 23 GHz continuum emission37, while red contours are the 5.6 GHz continuum emission4. The contour levels are between 20% and 80% and increment by 20% of the peak intensity. The synthesized beams at the two frequencies are shown in the top left and top right corners, respectively. At both frequencies, the radio continuum emission is unresolved or marginally resolved. The background image and gray contours show the ALMA 1.3 mm continuum emission, same as in Fig. 1.

Extended Data Fig. 2 Gas temperatures in the disk.

The two maps are derived from two groups of molecular lines: CH3CN on the left, and 13CH3CN on the right, with the same scale range for comparison. The green contours show the continuum emission, with the same contour levels as in Fig. 1a.

Extended Data Fig. 3 Toomre Q parameters in the disk with different assumptions.

Left: the case when using the sound speed only. Right: the case when using the epicyclic frequency following Equ. (5).

Extended Data Fig. 4 A more extensive parameter space of perturbation-induced structure formation.

When the periastron distance is small (bottom panels), the perturber penetrates the disk and leaves a strong dynamical impact, thus truncating the disk. When large (top panels), the dynamical effect becomes insignificant. When the angular velocity at the periastron is low (left panels), the perturber is able to resonate only with outer radii of the disk that rotate more slowly. When high (right panels), the perturber resonates with the inner disk, disturbing smaller radii than observed. The only viable solution remains to the one identified in Fig. 3.

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Lu, X., Li, GX., Zhang, Q. et al. A massive Keplerian protostellar disk with flyby-induced spirals in the Central Molecular Zone. Nat Astron (2022). https://doi.org/10.1038/s41550-022-01681-4

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