Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Change in the chemical composition of infalling gas forming a disk around a protostar

Abstract

IRAS 04368+2557 is a solar-type (low-mass) protostar embedded in a protostellar core (L1527) in the Taurus molecular cloud1,2, which is only 140 parsecs away from Earth, making it the closest large star-forming region. The protostellar envelope has a flattened shape with a diameter of a thousand astronomical units (1 au is the distance from Earth to the Sun), and is infalling and rotating3,4,5. It also has a protostellar disk with a radius of 90 au (ref. 6), from which a planetary system is expected to form7,8. The interstellar gas, mainly consisting of hydrogen molecules, undergoes a change in density of about three orders of magnitude as it collapses from the envelope into the disk, while being heated from 10 kelvin to over 100 kelvin in the mid-plane, but it has hitherto not been possible to explore changes in chemical composition associated with this collapse. Here we report that the unsaturated hydrocarbon molecule cyclic-C3H2 resides in the infalling rotating envelope, whereas sulphur monoxide (SO) is enhanced in the transition zone at the radius of the centrifugal barrier (100 ± 20 au), which is the radius at which the kinetic energy of the infalling gas is converted to rotational energy. Such a drastic change in chemistry at the centrifugal barrier was not anticipated, but is probably caused by the discontinuous infalling motion at the centrifugal barrier and local heating processes there.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: IRAS 04368+2557 in the cyclic-C3H2 (523–432) and SO (JN = 78–67) lines.
Figure 2: A model of an infalling rotating envelope.

Similar content being viewed by others

References

  1. Torres, R. M., Loinard, L., Mioduszewski, A. J. & Rodriguez, L. F. VLBA determination of the distance to nearby star-forming regions. II. Hubble 4 and HDE 283572 in Taurus. Astrophys. J. 671, 1813–1819 (2007)

    Article  ADS  CAS  Google Scholar 

  2. Andre, P., Ward-Thompson, D. & Barsony, M. Submillimeter continuum observations of Rho Ophiuchi A—the candidate protostar VLA 1623 and prestellar clumps. Astrophys. J. 406, 122–141 (1993)

    Article  ADS  Google Scholar 

  3. Ohashi, N., Hayashi, M., Ho, P. T. P. & Momose, M. Interferometric imaging of IRAS04368+2557 in the L1527 molecular cloud core: a dynamically infalling envelope with rotation. Astrophys. J. 475, 211–223 (1997)

    Article  ADS  CAS  Google Scholar 

  4. Shirley, Y. L., Evans, N. J., II & Rawlings, J. M. C. Tracing the mass during low-mass star formation. III. Models of the submillimeter dust continuum emission from class 0 protostars. Astrophys. J. 575, 337–353 (2002)

    Article  ADS  Google Scholar 

  5. Yen, H.-W., Takakuwa, S., Ohashi, N. & Ho, P. T. P. Unveiling the evolutionary sequence from infalling envelopes to Keplerian disks around low-mass protostars. Astrophys. J. 772, 22 (2013)

    Article  ADS  Google Scholar 

  6. Tobin, J. J. et al. A 0.2-solar-mass protostar with a Keplerian disk in the very young L1527 IRS system. Nature 492, 83–85 (2012)

    Article  ADS  CAS  Google Scholar 

  7. McKee, C. F. & Ostriker, E. C. Theory of star formation. Annu. Rev. Astron. Astrophys. 45, 565–687 (2007)

    Article  ADS  CAS  Google Scholar 

  8. Williams, J. P. & Cieza, L. A. Protoplanetary disks and their evolution. Annu. Rev. Astron. Astrophys. 49, 67–117 (2011)

    Article  ADS  Google Scholar 

  9. Tobin, J. J. et al. Modeling the resolved disk around the class 0 protostar L1527. Astrophys. J. 771, 48 (2013)

    Article  ADS  Google Scholar 

  10. Aikawa, Y., Wakelam, V., Garrod, R. T. & Herbst, E. Molecular evolution and star formation: from prestellar cores to protostellar cores. Astrophys. J. 674, 993–1005 (2008)

    Article  ADS  Google Scholar 

  11. Aikawa, Y., Wakelam, V., Hersant, F., Garrod, R. T. & Herbst, E. From prestellar to protostellar cores. II. Time dependence and deuterium fractionation. Astrophys. J. 760, 40 (2012)

    Article  ADS  Google Scholar 

  12. Wakelam, V. et al. Sulphur chemistry and molecular shocks: the case of NGC1333-IRAS2. Astron. Astrophys. 437, 149–158 (2005)

    Article  ADS  CAS  Google Scholar 

  13. Neufeld, D. A. & Hollenbach, D. J. Dense molecular shocks and accretion onto protostellar disks. Astrophys. J. 428, 170–185 (1994)

    Article  ADS  CAS  Google Scholar 

  14. Herbst, E. & van Dishoeck, E. F. Complex organic interstellar molecules. Annu. Rev. Astron. Astrophys. 47, 427–480 (2009)

    Article  ADS  CAS  Google Scholar 

  15. Caselli, P. & Ceccarelli, C. Our astrochemical heritage. Astron. Astrophys. Rev. 20, 56 (2012)

    Article  ADS  Google Scholar 

  16. Visser, R., Doty, S. D. & van Dishoeck, E. F. The chemical history of molecules in circumstellar disks II. Gas-phase species. Astron. Astrophys. 534, A132 (2011)

    Article  ADS  Google Scholar 

  17. Hincelin, U., Wakelam, V., Commercon, B., Hersant, F. & Guilloteau, S. Survival of interstellar molecules to prestellar dense core collapse and early phases of disk formation. Astrophys. J. 775, 44 (2013)

    Article  ADS  Google Scholar 

  18. Sakai, N., Sakai, T., Hirota, T. & Yamamoto, S. Distributions of carbon-chain molecules in L1527. Astrophys. J. 722, 1633–1643 (2010)

    Article  ADS  CAS  Google Scholar 

  19. 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 (Astronomical Society of the Pacific, Conference Series 376, 2007)

    Google Scholar 

  20. Bachiller, R., Perez Gutierrez, M., Kumar, M. S. N. & Tafalla, M. Chemically active outflow L1157. Astron. Astrophys. 372, 899–912 (2001)

    Article  ADS  CAS  Google Scholar 

  21. Wakelam, V. et al. Sulphur-bearing species in the star forming region L1689N. Astron. Astrophys. 413, 609–622 (2004)

    Article  ADS  CAS  Google Scholar 

  22. Hogerheijde, M. R. From infall to rotation around young stellar objects: a transitional phase with a 2000 AU radius contracting disk? Astrophys. J. 553, 618–632 (2001)

    Article  ADS  CAS  Google Scholar 

  23. Takakuwa, S. et al. A Keplerian circumbinary disk around the protostellar system L1551 NE. Astrophys. J. 754, 52 (2012)

    Article  ADS  Google Scholar 

  24. Ceccarelli, C., Maret, S., Tielens, A. G. G. M., Castets, A. & Caux, E. Theoretical H2CO emission from protostellar envelopes. Astron. Astrophys. 410, 587–595 (2003)

    Article  ADS  CAS  Google Scholar 

  25. Dubernet, M.-L. et al. BASECOL2012: a collisional database repository and web service within the Virtual Atomic and Molecular Data Centre (VAMDC). Astron. Astrophys. 553, A50 (2013); http://basecol.obspm.fr

    Article  Google Scholar 

  26. Chandra, S. & Kegel, W. H. Collisional rates for asymmetrical top molecules. Astrophys. J. (suppl.). 142, 113–118 (2000)

    ADS  CAS  Google Scholar 

  27. Lique, F., Senent, M.-L., Spielfiedel, A. & Feautrier, N. Rotationally inelastic collisions of SO(X3Σ) with H2: potential energy surface and rate coefficients for excitation by para-H2 at low temperature. J. Chem. Phys. 126, 164312 (2007)

    Article  ADS  CAS  Google Scholar 

  28. Sakai, N., Sakai, T., Hitora, T. & Yamamoto, S. Abundant carbon-chain molecules toward the low-mass protostar IRAS04368+2557 in L1527. Astrophys. J. 672, 371–381 (2008)

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We thank T. Hanawa and K. Furuya for discussions. This paper makes use of the ALMA dataset ADS/JAO.ALMA#2011.0.00604.S. ALMA is a partnership of the ESO (representing its member states), the NSF (USA) and NINS (Japan), together with the NRC (Canada) and the NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by the ESO, the AUI/NRAO and the NAOJ. We thank the ALMA staff for their support. N.S. and S.Y. acknowledge financial support from Grants-in-Aid from the Ministry of Education, Culture, Sports, Science and Technologies of Japan (21224002, 25400223 and 25108005), and by JSPS and MAEE under the Japan–France integrated action programme (SAKURA). T.H. acknowledges financial support from Grants-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technologies of Japan (21224002, 24684011 and 25108005). C.C. and C.K. acknowledge financial support from the French Agence Nationale pour la Recherche (ANR) project FORCOMS (contract ANR-08-BLAN-0225) and from the Partenariats Hubert Curien (PHC) Programme SAKURA 25765VC.

Author information

Authors and Affiliations

Authors

Contributions

N.S. led the project and participated in data reduction. All authors contributed to the data analysis, discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Nami Sakai.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Distribution of 0.8-mm continuum emission from dust grains.

The synthesized beam size is 0.61′′ × 0.39′′. Contour levels are −10σ, −5σ, 5σ, 10σ, 20σ, 40σ, 80σ and 160σ where 1σ is 1.1 mJy.

Extended Data Figure 2 Integrated intensity maps and PV diagrams of cyclic-C3H2 (918–827/928–817) and SO(JN = 76–65).

Contours are every 3σ (34.5 mJy beam−1 km s−1), starting from 3σ (the outermost contour), for a, every 3σ (30 mJy beam−1), starting from 3σ, for b, every 20σ (140 mJy beam−1 km s−1), starting from 10σ, for c, and every 3σ (12 mJy beam−1), starting from 3σ, for d.

Extended Data Figure 3 Velocity profile along the line of sight.

a, A schematic illustration of the infalling rotating envelope and definition of the coordinates. An observer is on the left-hand side, and is looking at the envelope in an edge-on configuration. In front of the radius of the centrifugal barrier, r0, the accretion shock appears. Inward of the centrifugal barrier, a disk structure is expected. b, Velocity profile along the line of sight with an offset of xau from the protostar. Only the velocity field of the infalling rotating envelope is shown.

Extended Data Figure 4 Velocity channel maps of the SO JN = 78-67 line.

Contours show 3σ, 6σ, 9σ, 12σ, 15σ, 20σ, 30σ and 40σ where 1σ is 7 mJy beam−1. The cross mark represents the continuum peak position.

Extended Data Figure 5 Velocity channel maps of the cyclic-C3H2 523-432 line.

Contours show every 3σ where 1σ is 4 mJy beam−1. The cross mark represents the continuum peak position.

Extended Data Figure 6 Velocity structure of the SO JN = 78–67 line.

a, Position velocity map along the east direction through the protostar position. Contours are every 4σ (28 mJy beam−1) starting from 2σ. No effect of the outflow can be recognized. b, First moment map. The lowest level is 3σ. The cross mark represents the continuum peak position.

Extended Data Figure 7 Spectral profiles of SO (JN = 78-67) line.

Spectra towards the three positions centred at the protostar position are shown.

Extended Data Figure 8 χ2 plot for constraining the SO column density, the H2 density and the gas temperature.

a, The plot is prepared from the minimum χ2 value with respect to the H2 density and the temperature for each SO column density. b, Contours represent the χ2 value as a function of the H2 density and the temperature with the SO column density of 4 × 1014 cm−2.

Extended Data Table 1 Flux densities

Supplementary information

Supplementary Information

This file contains the Supplementary Discussion and Supplementary References. (PDF 154 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Sakai, N., Sakai, T., Hirota, T. et al. Change in the chemical composition of infalling gas forming a disk around a protostar. Nature 507, 78–80 (2014). https://doi.org/10.1038/nature13000

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature13000

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing