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.

Water vapour and hydrogen in the terrestrial-planet-forming region of a protoplanetary disk


Planetary systems (ours included) formed in disks of dust and gas around young stars. Disks are an integral part of the star and planet formation process1,2, and knowledge of the distribution and temperature of inner-disk material is crucial for understanding terrestrial planet formation3, giant planet migration4, and accretion onto the central star5. Although the inner regions of protoplanetary disks in nearby star-forming regions subtend only a few nano-radians, near-infrared interferometry has recently enabled the spatial resolution of these terrestrial zones. Most observations have probed only dust6, which typically dominates the near-infrared emission. Here I report spectrally dispersed near-infrared interferometric observations that probe the gas (which dominates the mass and dynamics of the inner disk), in addition to the dust, within one astronomical unit (1 au, the Sun–Earth distance) of the young star MWC 480. I resolve gas, including water vapour and atomic hydrogen, interior to the edge of the dust disk; this contrasts with results of previous spectrally dispersed interferometry observations7,8. Interactions of this accreting gas with migrating planets may lead to short-period exoplanets like those detected around main-sequence stars4. The observed water vapour is probably produced by the sublimation of migrating icy bodies9, and provides a potential reservoir of water for terrestrial planets10.

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

Access options

Rent or buy this article

Prices vary by article type



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

Figure 1: Angular size of the near-infrared emission from MWC 480 as a function of wavelength.
Figure 2: Measured V 2 and fluxes, compared to the predictions of simple physical models.
Figure 3: The environment within 1  au of the young star MWC 480.


  1. 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  CAS  Google Scholar 

  2. Safronov, V. S. Evolution of the Protoplanetary Cloud and Formation of the Earth and the Planets [in Russian] NASA TTF-677 (Nauka, Moscow, 1969)

    Google Scholar 

  3. Raymond, S. N., Quinn, T. & Lunine, J. I. Making other Earths: dynamical simulations of terrestrial planet formation and water delivery. Icarus 168, 1–17 (2004)

    Article  ADS  CAS  Google Scholar 

  4. Lin, D. N. C., Bodenheimer, P. & Richardson, D. C. Orbital migration of the planetary companion of 51 Pegasi to its present location. Nature 380, 606–607 (1996)

    Article  ADS  CAS  Google Scholar 

  5. Königl, A. Disk accretion onto magnetic T Tauri stars. Astrophys. J. 370, L39–L43 (1991)

    Article  ADS  Google Scholar 

  6. Millan-Gabet, R. et al. in Protostars and Planets V (eds Reipurth, B., Jewitt, D. & Keil, K.) 539–554 (Univ. Arizona Press, Tucson, 2007)

    Google Scholar 

  7. Malbet, F. et al. Disk and wind interaction in the young stellar object MWC 297 spatially resolved with AMBER/VLTI. Astron. Astrophys. 464, 43–53 (2007)

    Article  ADS  CAS  Google Scholar 

  8. 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)

    Article  ADS  CAS  Google Scholar 

  9. Ciesla, F. J. & Cuzzi, J. N. The evolution of the water distribution in a viscous protoplanetary disk. Icarus 181, 178–204 (2006)

    Article  ADS  Google Scholar 

  10. Drake, M. J. Origin of water in the terrestrial planets. Meteorit. Planet. Sci. 40, 519–527 (2005)

    Article  ADS  CAS  Google Scholar 

  11. Eisner, J. A. et al. Stellar and molecular radii of a Mira star: first observations with the Keck Interferometer grism. Astrophys. J. 654, L77–L80 (2007)

    Article  ADS  CAS  Google Scholar 

  12. Colavita, M. M. & Wizinowich, P. L. in Interferometry for Optical Astronomy II (ed. Traub, W. A.) Proc. SPIE 4838, 79–88 (2003)

    Book  Google Scholar 

  13. Colavita, M. et al. Observations of DG Tauri with the Keck Interferometer. Astrophys. J. 592, L83–L86 (2003)

    Article  ADS  Google Scholar 

  14. Mannings, V., Koerner, D. W. & Sargent, A. I. A rotating disk of gas and dust around a young counterpart to β Pictoris. Nature 388, 555–557 (1997)

    Article  ADS  CAS  Google Scholar 

  15. Eisner, J. A., Lane, B. F., Hillenbrand, L., Akeson, R. & Sargent, A. Resolved inner disks around Herbig Ae/Be stars. Astrophys. J. 613, 1049–1071 (2004)

    Article  ADS  CAS  Google Scholar 

  16. Monnier, J. D. et al. Few skewed disks found in first closure-phase survey of Herbig Ae/Be stars. Astrophys. J. 647, 444–463 (2006)

    Article  ADS  CAS  Google Scholar 

  17. Eisner, J. A., Chiang, E. I., Lane, B. F. & Akeson, R. L. Spectrally dispersed K-band interferometric observations of Herbig Ae/Be sources: inner disk temperature profiles. Astrophys. J. 657, 347–358 (2007)

    Article  ADS  Google Scholar 

  18. Osterbrock, D. E. Astrophysics of Gaseous Nebulae and Active Galactic Nuclei Ch. 4 (Univ. Science Books, California, 1989)

    Book  Google Scholar 

  19. Isella, A. & Natta, A. The shape of the inner rim in proto-planetary disks. Astron. Astrophys. 438, 899–907 (2005)

    Article  ADS  Google Scholar 

  20. Ludwig, C. B. Measurements of the curves-of-growth of hot water vapor. Appl. Opt. 10, 1057–1073 (1971)

    Article  ADS  CAS  Google Scholar 

  21. Pollack, J. B. et al. Composition and radiative properties of grains in molecular clouds and accretion disks. Astrophys. J. 421, 615–639 (1994)

    Article  ADS  CAS  Google Scholar 

  22. Najita, J., Carr, J. S. & Tokunaga, A. T. High-resolution spectroscopy of BR gamma emission in young stellar objects. Astrophys. J. 456, 292–299 (1996)

    Article  ADS  CAS  Google Scholar 

  23. Calvet, N. & Gullbring, E. The structure and emission of the accretion shock in T Tauri stars. Astrophys. J. 509, 802–818 (1998)

    Article  ADS  Google Scholar 

  24. Muzerolle, J., D'Alessio, P., Calvet, N. & Hartmann, L. Magnetospheres and disk accretion in Herbig Ae/Be stars. Astrophys. J. 617, 406–417 (2004)

    Article  ADS  CAS  Google Scholar 

  25. Carr, J. S., Tokunaga, A. T. & Najita, J. Hot H2O emission and evidence for turbulence in the disk of a young star. Astrophys. J. 603, 213–220 (2004)

    Article  ADS  CAS  Google Scholar 

  26. Najita, J. R., Carr, J. S., Glassgold, A. E. & Valenti, J. A. in Protostars and Planets V (eds Reipurth, B., Jewitt, D. & Keil, K.) 507–522 (Univ. Arizona Press, Tucson, 2007)

    Google Scholar 

  27. van den Ancker, M. E., de Winter, D., Tjin, A. & Djie, H. R. E. HIPPARCOS photometry of Herbig Ae/Be stars. Astron. Astrophys. 330, 145–154 (1998)

    ADS  Google Scholar 

  28. Marcy, G. et al. Observed properties of exoplanets: masses, orbits, and metallicities. Progr. Theor. Phys. 158 (Suppl.). 24–42 (2005)

    Article  Google Scholar 

  29. Dullemond, C. P., Dominik, C. & Natta, A. Passive irradiated circumstellar disks with an inner hole. Astrophys. J. 560, 957–969 (2001)

    Article  ADS  Google Scholar 

  30. Shu, F. et al. Magnetocentrifugally driven flows from young stars and disks. 1: A generalized model. Astrophys. J. 429, 781–796 (1994)

    Article  ADS  Google Scholar 

Download references


Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency’s scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. I thank the entire Keck Interferometer team for their invaluable contributions to these observations. I also acknowledge input into this work (and this manuscript) from R. Akeson, E. Chiang, A. Glassgold, J. Graham, J. Najita and R. White. I am supported by a Miller Research Fellowship.

Author information

Authors and Affiliations


Corresponding author

Correspondence to J. A. Eisner.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Notes with additional evidence that effects in the data attributed to water vapor emission are not artifacts of the data calibration or modeling procedures and Supplementary Figure 1 with Legend. (PDF 110 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Eisner, J. Water vapour and hydrogen in the terrestrial-planet-forming region of a protoplanetary disk. Nature 447, 562–564 (2007).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


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