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The formation of a quadruple star system with wide separation

Abstract

The initial multiplicity of stellar systems is highly uncertain. A number of mechanisms have been proposed to explain the origin of binary and multiple star systems, including core fragmentation, disk fragmentation and stellar capture1,2,3. Observations show that protostellar and pre-main-sequence multiplicity is higher than the multiplicity found in field stars4,5,6,7, which suggests that dynamical interactions occur early, splitting up multiple systems and modifying the initial stellar separations8,9. Without direct, high-resolution observations of forming systems, however, it is difficult to determine the true initial multiplicity and the dominant binary formation mechanism. Here we report observations of a wide-separation (greater than 1,000 astronomical units) quadruple system composed of a young protostar and three gravitationally bound dense gas condensations. These condensations are the result of fragmentation of dense gas filaments, and each condensation is expected to form a star on a timescale of 40,000 years. We determine that the closest pair will form a bound binary, while the quadruple stellar system itself is bound but unstable on timescales of 500,000 years (comparable to the lifetime of the embedded protostellar phase10). These observations suggest that filament fragmentation on length scales of about 5,000 astronomical units offers a viable pathway to the formation of multiple systems.

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Figure 1: High-angular-resolution image of dense gas and stellar progenitors.
Figure 2: Ratio of kinetic to gravitational energy for B5-IRS1 and B5-Cond2 as a function of final stellar mass.

References

  1. Stamatellos, D. & Whitworth, A. P. The properties of brown dwarfs and low-mass hydrogen-burning stars formed by disc fragmentation. Mon. Not. R. Astron. Soc. 392, 413–427 (2009)

    Article  ADS  CAS  Google Scholar 

  2. Offner, S. S. R., Kratter, K. M., Matzner, C. D., Krumholz, M. R. & Klein, R. I. The formation of low-mass binary star systems via turbulent fragmentation. Astrophys. J. 725, 1485–1494 (2010)

    Article  ADS  Google Scholar 

  3. Moeckel, N. & Bate, M. R. On the evolution of a star cluster and its multiple stellar systems following gas dispersal. Mon. Not. R. Astron. Soc. 404, 721–737 (2010)

    Article  ADS  Google Scholar 

  4. Duchêne, G. & Kraus, A. Stellar multiplicity. Annu. Rev. Astron. Astrophys. 51, 269–310 (2013)

    Article  ADS  Google Scholar 

  5. Chen, X. et al. SMA observations of class 0 protostars: a high angular resolution survey of protostellar binary systems. Astrophys. J. 768, 110 (2013)

    Article  ADS  Google Scholar 

  6. Connelley, M. S., Reipurth, B. & Tokunaga, A. T. The evolution of the multiplicity of embedded protostars. I. Sample properties and binary detections. Astron. J. 135, 2496–2525 (2008)

    Article  ADS  Google Scholar 

  7. Connelley, M. S., Reipurth, B. & Tokunaga, A. T. The evolution of the multiplicity of embedded protostars. II. Binary separation distribution and analysis. Astron. J. 135, 2526–2536 (2008)

    Article  ADS  Google Scholar 

  8. Reipurth, B. & Mikkola, S. Formation of the widest binary stars from dynamical unfolding of triple systems. Nature 492, 221–224 (2012)

    Article  ADS  CAS  Google Scholar 

  9. Reipurth, B. et al. Multiplicity in early stellar evolution. Preprint at http://ArXiv.org/abs/1403.1907 (2014)

    Google Scholar 

  10. Evans, N. J., II et al. The Spitzer c2d legacy results: star-formation rates and efficiencies; evolution and lifetimes. Astrophys. J. 181, 321–350 (2009)

    Article  Google Scholar 

  11. Fuller, G. A. et al. Anatomy of the Barnard 5 core. Astrophys. J. 376, 135–149 (1991)

    Article  ADS  CAS  Google Scholar 

  12. Pineda, J. E. et al. Direct observation of a sharp transition to coherence in dense cores. Astrophys. J. 712, L116–L121 (2010)

    Article  ADS  CAS  Google Scholar 

  13. Goodman, A. A., Barranco, J. A., Wilner, D. J. & Heyer, M. H. Coherence in dense cores. II. The transition to coherence. Astrophys. J. 504, 223–246 (1998)

    Article  ADS  CAS  Google Scholar 

  14. Pineda, J. E. et al. Expanded Very Large Array observations of the Barnard 5 star-forming core: embedded filaments revealed. Astrophys. J. 739, L2 (2011)

    Article  ADS  Google Scholar 

  15. Perley, R. A., Chandler, C. J., Butler, B. J. & Wrobel, J. M. The expanded Very Large Array: a new telescope for new science. Astrophys. J. 739, L1 (2011)

    Article  ADS  Google Scholar 

  16. Lada, C. J. Stellar multiplicity and the initial mass function: most stars are single. Astrophys. J. 640, L63–L66 (2006)

    Article  ADS  Google Scholar 

  17. Parker, R. J. & Quanz, S. P. On the frequency of planetary systems around G dwarfs. Mon. Not. R. Astron. Soc. 436, 650–658 (2013)

    Article  ADS  Google Scholar 

  18. Tohline, J. E. The origin of binary stars. Annu. Rev. Astron. Astrophys. 40, 349–385 (2002)

    Article  ADS  Google Scholar 

  19. Kamazaki, T., Saito, M., Hirano, N. & Kawabe, R. Millimeter-wave interferometric study of the rho Ophiuchi A region. I. Small-scale structures of dust continuum sources. Astrophys. J. 548, 278–287 (2001)

    Article  ADS  Google Scholar 

  20. Nakamura, F., Takakuwa, S. & Kawabe, R. Substellar-mass condensations in prestellar cores. Astrophys. J. 758, L25 (2012)

    Article  ADS  Google Scholar 

  21. Rosolowsky, E. W., Pineda, J. E., Kauffmann, J. & Goodman, A. A. Structural analysis of molecular clouds: dendrograms. Astrophys. J. 679, 1338–1351 (2008)

    Article  ADS  CAS  Google Scholar 

  22. Brassfield, E. & Bourke, T. L. Submillimeter Array observations of embedded class I object Barnard 5 IRS1. Bull. Am. Astron. Soc. 43, 340.09 (2011)

    ADS  Google Scholar 

  23. Motte, F., Andre, P. & Neri, R. The initial conditions of star formation in the rho Ophiuchi main cloud: wide-field millimeter continuum mapping. Astron. Astrophys. 336, 150–172 (1998)

    ADS  CAS  Google Scholar 

  24. Alves, J., Lombardi, M. & Lada, C. J. The mass function of dense molecular cores and the origin of the IMF. Astron. Astrophys. 462, L17–L21 (2007)

    Article  ADS  CAS  Google Scholar 

  25. André, P. et al. From filamentary networks to dense cores in molecular clouds: toward a new paradigm for star formation. Preprint at http://ArXiv.org/abs/1312.6232 (2014)

  26. Matzner, C. D. & McKee, C. F. Efficiencies of low-mass star and star cluster formation. Astrophys. J. 545, 364–378 (2000)

    Article  ADS  Google Scholar 

  27. Machida, M. N. & Hosokawa, T. Evolution of protostellar outflow around low-mass protostar. Mon. Not. R. Astron. Soc. 431, 1719–1744 (2013)

    Article  ADS  Google Scholar 

  28. Offner, S. S. R. & Arce, H. G. Investigations of protostellar outflow launching and gas entrainment: hydrodynamic simulations and molecular emission. Astrophys. J. 784, 61 (2014)

    Article  ADS  Google Scholar 

  29. Kirk, H. et al. Filamentary accretion flows in the embedded Serpens South protocluster. Astrophys. J. 766, 115 (2013)

    Article  ADS  Google Scholar 

  30. Peretto, N. et al. Global collapse of molecular clouds as a formation mechanism for the most massive stars. Astron. Astrophys. 555, A112 (2013)

    Article  Google Scholar 

  31. McMullin, J. P., Waters, B., Schiebel, D., Young, W. & Golap, K. in Astronomical Data Analysis Software and Systems XVI (eds Shaw, R. A., Hill, F. & Bell, D. J. ) 127–130 (Astron. Soc. Pacif. Conf. Ser. Vol. 376, 2007)

    Google Scholar 

  32. Holland, W. S. et al. SCUBA-2: the 10,000 pixel bolometer camera on the James Clerk Maxwell Telescope. Mon. Not. R. Astron. Soc. 430, 2513–2533 (2013)

    Article  ADS  Google Scholar 

  33. Chapin, E. L. et al. SCUBA-2: iterative map-making with the Sub-Millimetre User Reduction Facility. Mon. Not. R. Astron. Soc. 430, 2545–2573 (2013)

    Article  ADS  Google Scholar 

  34. Dempsey, J. T. et al. SCUBA-2: on-sky calibration using submillimetre standard sources. Mon. Not. R. Astron. Soc. 430, 2534–2544 (2013)

    Article  ADS  Google Scholar 

  35. Hildebrand, R. H. The determination of cloud masses and dust characteristics from submillimetre thermal emission. Q. J. R. Astron. Soc. 24, 267–282 (1983)

    ADS  Google Scholar 

  36. Foster, J. B. et al. Dense cores in Perseus: the influence of stellar content and cluster environment. Astrophys. J. 696, 298–319 (2009)

    Article  ADS  CAS  Google Scholar 

  37. Enoch, M. L. et al. Bolocam survey for 1.1 mm dust continuum emission in the c2d legacy clouds. I. Perseus. Astrophys. J. 638, 293–313 (2006)

    Article  ADS  CAS  Google Scholar 

  38. Shu, F. H. Self-similar collapse of isothermal spheres and star formation. Astrophys. J. 214, 488–497 (1977)

    Article  ADS  Google Scholar 

  39. Enoch, M. L. et al. The mass distribution and lifetime of prestellar cores in Perseus, Serpens, and Ophiuchus. Astrophys. J. 684, 1240–1259 (2008)

    Article  ADS  CAS  Google Scholar 

  40. Baumgardt, H., Hut, P. & Heggie, D. C. Long-term evolution of isolated N-body systems. Annu. Rev. Astron. Astrophys. 336, 1069–1081 (2002)

    Google Scholar 

  41. Parker, R. J. & Meyer, M. R. Binaries in the field: fossils of the star formation process? Mon. Not. R. Astron. Soc. 442, 3722–3736 (2014)

    Article  ADS  Google Scholar 

  42. Astropy Collaboration et al. Astropy: A community Python package for astronomy. Astron. Astrophys. 558, A33 (2013)

Download references

Acknowledgements

We thank K. Todorov for discussions and comments that improved the paper. We acknowledge support from the Swiss National Science Foundation project CRSII2_141880 (J.E.P.), NSF CAREER award AST-0845619 (H.G.A.), NSF grant AST-0908159 (A.A.G.), ERC project PALs 320620 (P.C.) and NASA grant NNX09AB89G (T.L.B.). S.S.R.O. acknowledges support from NASA through Hubble Fellowship grant 51311.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. R.J.P. acknowledges support from the Royal Astronomical Society through a research fellowship. This research made use of astrodendro (http://www.dendrograms.org), Astropy, and APLpy (http://aplpy.github.com). The James Clerk Maxwell Telescope is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the UK, the National Research Council of Canada, and (up to 31 March 2013) the Netherlands Organisation for Scientific Research. Additional funds for the construction of SCUBA-2 were provided by the Canada Foundation for Innovation. The National Radio Astronomy Observatory is a facility of the NSF operated under cooperative agreement by Associated Universities, Inc.

Author information

Authors and Affiliations

Authors

Contributions

J.E.P. led the project and reduced the VLA data. J.E.P. and S.S.R.O. wrote the manuscript. R.J.P. conducted the stability analysis of the multiple system. All authors contributed to the VLA proposal, discussed the results and implications, and commented on the manuscript.

Corresponding author

Correspondence to Jaime E. Pineda.

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The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Dust continuum emission maps of Barnard 5.

a, b, Dust continuum emission observed with SCUBA-2 at 450 µm (a) and 850 µm (b). Contour levels are drawn at 3, 6, 9, 12 and 15× rms, where rms is 0.23 mJy per pixel and 0.026 mJy per pixel in the 450 µm and 850 µm maps, respectively. Emission from dust associated with the protostar B5-IRS1 dominates the field, and it makes it difficult to extract the emission from B5-Cond2 and B5-Cond3. B5-Cond1 is clearly detected in the dust continuum emission. Since the dust continuum emission does show the presence of the filaments in low level emission, we conclude they are real column density features. Filled white circles at bottom left corners show the angular resolution of the observations. Blue- and orange-filled circles show the condensation centres, while the filled stars indicate the protostar (B5-IRS1) location.

Extended Data Figure 2 Mass and virial parameter as a function of radius for condensations.

a, The enclosed condensation mass, derived from NH3(1,1), at different effective radii for each condensation; b, the corresponding virial parameter as a function of effective radius for each condensation. The condensation mass grows rapidly with radius, with a profile similar to one expected for a density distribution of ρ r−1.5 (dotted line in a) until it is close to the condensation boundary. In comparison, the dashed line shows the expected result in hydrostatic equilibrium (ρ r−2), which is different to the observed distribution. The virial parameter decreases with radius until it reaches a minimum of 1.5, and then it slowly increases until it reaches the condensation boundary. Notice that virial parameters below the horizontal line (α = 2) imply bound condensations. The grey shaded region marks the regime where the effective radius is smaller than the angular resolution of the observations. The circles show the values at the half-mass radius.

Extended Data Table 1 Condensation and protostar parameters

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Pineda, J., Offner, S., Parker, R. et al. The formation of a quadruple star system with wide separation. Nature 518, 213–215 (2015). https://doi.org/10.1038/nature14166

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