Skip to main content

Thank you for visiting 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.

Flows of gas through a protoplanetary gap

This article has been updated


The formation of gaseous giant planets is thought to occur in the first few million years after stellar birth. Models1 predict that the process produces a deep gap in the dust component (shallower in the gas2,3,4). Infrared observations of the disk around the young star HD 142527 (at a distance of about 140 parsecs from Earth) found an inner disk about 10 astronomical units (au) in radius5 (1 au is the Earth–Sun distance), surrounded by a particularly large gap6 and a disrupted7 outer disk beyond 140 au. This disruption is indicative of a perturbing planetary-mass body at about 90 au. Radio observations8,9 indicate that the bulk mass is molecular and lies in the outer disk, whose continuum emission has a horseshoe morphology8. The high stellar accretion rate10 would deplete the inner disk11 in less than one year, and to sustain the observed accretion matter must therefore flow from the outer disk and cross the gap. In dynamical models, the putative protoplanets channel outer-disk material into gap-crossing bridges that feed stellar accretion through the inner disk12. Here we report observations of diffuse CO gas inside the gap, with denser HCO+ gas along gap-crossing filaments. The estimated flow rate of the gas is in the range of 7 × 10−9 to 2 × 10−7 solar masses per year, which is sufficient to maintain accretion onto the star at the present rate.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: ALMA observations of HD 142527, with a horseshoe dust continuum surrounding a gap that still contains gas.

Change history

  • 09 January 2013

    An affiliation and a figure citation were corrected.


  1. 1

    Lubow, S. H. & D’Angelo, G. Gas flow across gaps in protoplanetary disks. Astrophys. J. 641, 526–533 (2006)

    ADS  Article  Google Scholar 

  2. 2

    Fouchet, L., Gonzalez, J.-F. & Maddison, S. T. Planet gaps in the dust layer of 3D protoplanetary disks. I. Hydrodynamical simulations of T Tauri disks. Astron. Astrophys. 518, A16 (2010)

    Article  Google Scholar 

  3. 3

    Ayliffe, B. A., Laibe, G., Price, D. J. & Bate, M. R. On the accumulation of planetesimals near disc gaps created by protoplanets. Mon. Not. R. Astron. Soc. 423, 1450–1462 (2012)

    ADS  Article  Google Scholar 

  4. 4

    Zhu, Z., Nelson, R. P., Hartmann, L., Espaillat, C. & Calvet, N. Transitional and pretransitional disks: gap opening by multiple planets? Astrophys. J. 729, 47–58 (2011)

    ADS  Article  Google Scholar 

  5. 5

    van Boekel, R. et al. The building blocks of planets within the ‘terrestrial’ region of protoplanetary disks. Nature 432, 479–482 (2004)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Fukagawa, M. et al. Near-infrared images of protoplanetary disk surrounding HD 142527. Astrophys. J. 636, L153–L156 (2006)

    ADS  Article  Google Scholar 

  7. 7

    Casassus, S. et al. The dynamically disrupted gap in HD 142527. Astrophys. J. 754, L31–L35 (2012)

    ADS  Article  Google Scholar 

  8. 8

    Ohashi, N. Observational signature of planet formation: the ALMA view. Astrophys. Space Sci. 313, 101–107 (2008)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Öberg, K. I. et al. Disk imaging survey of chemistry with SMA. II. Southern sky protoplanetary disk data and full sample statistics. Astrophys. J. 734, 98–109 (2011)

    ADS  Article  Google Scholar 

  10. 10

    Garcia Lopez, R., Natta, A., Testi, L. & Habart, E. Accretion rates in Herbig Ae stars. Astron. Astrophys. 459, 837–842 (2006)

    ADS  Article  Google Scholar 

  11. 11

    Verhoeff, A. P. et al. The complex circumstellar environment of HD 142527. Astron. Astrophys. 528, A91–A103 (2011)

    Article  Google Scholar 

  12. 12

    Dodson-Robinson, S. E. & Salyk, C. Transitional disks as signposts of young, multiplanet systems. Astrophys. J. 738, 131–145 (2011)

    ADS  Article  Google Scholar 

  13. 13

    Fujiwara, H. et al. The asymmetric thermal emission of the protoplanetary disk surrounding HD 142527 seen by Subaru/COMICS. Astrophys. J. 644, L133–L136 (2006)

    ADS  CAS  Article  Google Scholar 

  14. 14

    Lyo, A.-R., Ohashi, N., Qi, C., Wilner, D. J. & Su, Y.-N. Millimeter observations of the transition disk around HD 135344B (SAO 206462). Astron. J. 142, 151–160 (2011)

    ADS  Article  Google Scholar 

  15. 15

    Mathews, G. S., Williams, J. P. & Ménard, F. 880 µm imaging of a transitional disk in Upper Scorpius: holdover from the era of giant planet formation? Astrophys. J. 753, 59–70 (2012)

    ADS  Article  Google Scholar 

  16. 16

    Tatulli, E. et al. Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD 104237. Astron. Astrophys. 464, 55–58 (2007)

    ADS  CAS  Article  Google Scholar 

  17. 17

    Kraus, S. et al. The origin of hydrogen line emission for five Herbig Ae/Be stars spatially resolved by VLTI/AMBER spectro-interferometry. Astron. Astrophys. 489, 1157–1173 (2008)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Eisner, J. A. et al. Spatially and spectrally resolved hydrogen gas within 0.1 AU of T Tauri and Herbig Ae/Be Stars. Astrophys. J. 718, 774–794 (2010)

    ADS  CAS  Article  Google Scholar 

  19. 19

    Carr, J. S., Mathieu, R. D. & Najita, J. R. Evidence for residual material in accretion disk gaps: CO fundamental emission from the T Tauri spectroscopic binary DQ Tauri. Astrophys. J. 551, 454–460 (2001)

    ADS  Article  Google Scholar 

  20. 20

    Najita, J., Carr, J. S. & Mathieu, R. D. Gas in the terrestrial planet region of disks: CO fundamental emission from T Tauri Stars. Astrophys. J. 589, 931–952 (2003)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Acke, B. & van den Ancker, M. E. Resolving the disk rotation of HD 97048 and HD 100546 in the [O I] 6300 Å line: evidence for a giant planet orbiting HD 100546. Astron. Astrophys. 449, 267–279 (2006)

    ADS  CAS  Article  Google Scholar 

  22. 22

    van der Plas, G. et al. The structure of protoplanetary disks surrounding three young intermediate mass stars. I. Resolving the disk rotation in the [OI] 6300 Å line. Astron. Astrophys. 485, 487–495 (2008)

    ADS  CAS  Article  Google Scholar 

  23. 23

    Salyk, C., Blake, G. A., Boogert, A. C. A. & Brown, J. M. High-resolution 5 µm spectroscopy of transitional disks. Astrophys. J. 699, 330–347 (2009)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Pontoppidan, K. M. et al. Spectroastrometric imaging of molecular gas within protoplanetary disk gaps. Astrophys. J. 684, 1323–1329 (2008)

    ADS  CAS  Article  Google Scholar 

  25. 25

    van der Plas, G. et al. Evidence for CO depletion in the inner regions of gas-rich protoplanetary disks. Astron. Astrophys. 500, 1137–1141 (2009)

    ADS  CAS  Article  Google Scholar 

  26. 26

    Pontoppidan, K. M., Blake, G. A. & Smette, A. The structure and dynamics of molecular gas in planet-forming zones: a CRIRES spectro-astrometric survey. Astrophys. J. 733, 84–100 (2011)

    ADS  Article  Google Scholar 

  27. 27

    Sacco, G. G. et al. High-resolution Spectroscopy of Ne II emission from young stellar objects. Astrophys. J. 747, 142 (2012)

    ADS  Article  Google Scholar 

  28. 28

    Piétu, V., Gueth, F., Hily-Blant, P., Schuster, K.-F. & Pety, J. High resolution imaging of the GG Tauri system at 267 GHz. Astron. Astrophys. 528, A81–A95 (2011)

    ADS  Article  Google Scholar 

  29. 29

    Beck, T. L. et al. Circumbinary gas accretion onto a central binary: infrared molecular hydrogen emission from GG Tau A. Astrophys. J. 754, 72–77 (2012)

    ADS  Article  Google Scholar 

  30. 30

    Regály, Z., Juhász, A., Sándor, Z. & Dullemond, C. P. Possible planet-forming regions on submillimetre images. Mon. Not. R. Astron. Soc. 419, 1701–1712 (2012)

    ADS  Article  Google Scholar 

Download references


This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00465.S. ALMA is a partnership of the ESO, NSF, NINS, NRC, NSC and ASIAA. The Joint ALMA Observatory is operated by the ESO, AUI/NRAO and NAOJ. This work was also based on observations obtained at the Gemini Observatory. Financial support was provided by Millennium Nucleus P10-022-F (Chilean Ministry of Economy) and additionally by grant FONDECYT 1100221 and grant 284405 from the European Union FP7 programme.

Author information




General design of ALMA project, data analysis and write-up: S.C. Discussion of infrared observations of gas in cavities: G.v.d.P. Hydrodynamical modelling: S.P.M. ALMA data reduction: A.H. and E.F. Infrared-image processing: D.M., J.H. and J.H.G. Contributions to ALMA Cycle 0 proposal: A.J., F.M., D.W. and A.M.H. Design of ALMA observations: A.W., A.H. and S.C. Authors W.R.F.D. to A.W. contributed equally. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Simon Casassus.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Text and Data 1-5, Supplementary References and Supplementary Figures 1-13. (PDF 10381 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Casassus, S., van der Plas, G., M, S. et al. Flows of gas through a protoplanetary gap. Nature 493, 191–194 (2013).

Download citation

Further reading


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.


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