Letter | Published:

Vigorous atmospheric motion in the red supergiant star Antares

Nature volume 548, pages 310312 (17 August 2017) | Download Citation

Subjects

Abstract

Red supergiant stars represent a late stage of the evolution of stars more massive than about nine solar masses, in which they develop complex, multi-component atmospheres. Bright spots have been detected in the atmosphere of red supergiants using interferometric imaging1,2,3,4,5. Above the photosphere of a red supergiant, the molecular outer atmosphere extends up to about two stellar radii6,7,8,9,10,11,12,13,14. Furthermore, the hot chromosphere (5,000 to 8,000 kelvin) and cool gas (less than 3,500 kelvin) of a red supergiant coexist at about three stellar radii15,16,17,18. The dynamics of such complex atmospheres has been probed by ultraviolet and optical spectroscopy19,20,21,22. The most direct approach, however, is to measure the velocity of gas at each position over the image of stars as in observations of the Sun. Here we report the mapping of the velocity field over the surface and atmosphere of the nearby red supergiant Antares. The two-dimensional velocity field map obtained from our near-infrared spectro-interferometric imaging reveals vigorous upwelling and downdrafting motions of several huge gas clumps at velocities ranging from about −20 to +20 kilometres per second in the atmosphere, which extends out to about 1.7 stellar radii. Convection alone cannot explain the observed turbulent motions and atmospheric extension, suggesting that an unidentified process is operating in the extended atmosphere.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    , , & Detection of a bright feature on the surface of Betelgeuse. Mon. Not. R. Astron. Soc. 245, 7–11 (1990)

  2. 2.

    , & Hotspots on late-type supergiants. Mon. Not. R. Astron. Soc. 285, 529–539 (1997)

  3. 3.

    et al. New views of Betelgeuse: multi-wavelength surface imaging and implications for models of hotspot generation. Mon. Not. R. Astron. Soc. 315, 635–645 (2000)

  4. 4.

    et al. Imaging the spotty surface of Betelgeuse in the H band. Astron. Astrophys. 508, 923–932 (2009)

  5. 5.

    et al. CHARA/MIRC observations of two M supergiants in Perseus OB1: temperature, Baysian modeling, and compressed sensing imaging. Astrophys. J. 785, 46 (2014)

  6. 6.

    Water on the early M supergiant stars α Orionis and μ Cephei. Astrophys. J. 538, 801–807 (2000)

  7. 7.

    Water in emission in the Infrared Space Observatory spectrum of the early M supergiant star μ Cephei. Astrophys. J. 540, L99–L102 (2000)

  8. 8.

    et al. Interferometric observations of the supergiant stars α Orionis and α Herculis with FLUOR at IOTA. Astron. Astrophys. 418, 675–685 (2004)

  9. 9.

    Warm water vapor envelope in the supergiants α Ori and α Her and its effects on the apparent size from the near-infrared to the mid-infrared. Astron. Astrophys. 421, 1149–1158 (2004)

  10. 10.

    et al. TEXES observations of M supergiants: dynamics and thermodynamics of wind acceleration. Astrophys. J. 701, 1464–1483 (2009)

  11. 11.

    et al. Spatially resolving the inhomogeneous structure of the dynamical atmosphere of Betelgeuse with VLTI/AMBER. Astron. Astrophys. 503, 183–195 (2009)

  12. 12.

    et al. Imaging the dynamical atmosphere of the red supergiant Betelgeuse in the CO first overtone lines with VLTI/AMBER. Astron. Astrophys. 529, A163 (2011)

  13. 13.

    et al. High spectral resolution imaging of the dynamical atmosphere of the red supergiant Antares in the CO first overtone lines with VLTI/AMBER. Astron. Astrophys. 555, A24 (2013)

  14. 14.

    et al. Properties of the CO and H2O MOLsphere of the red supergiant Betelgeuse from VLTI/AMBER observations. Astron. Astrophys. 572, A17 (2014)

  15. 15.

    & First image of the surface of a star with the Hubble Space Telescope. Astrophys. J. 463, L29–L32 (1996)

  16. 16.

    , , , & Large convection cells as the source of Betelgeuse’s extended atmosphere. Nature 392, 575–577 (1998)

  17. 17.

    & Spatially resolved, semiempirical model for the extended atmosphere of α Orionis (M2 Iab). Astrophys. J. 551, 1073–1098 (2001)

  18. 18.

    & Electron density and turbulence gradients within the extended atmosphere of the M supergiant Betelgeuse (α Orionis). Astrophys. J. 646, 1179–1202 (2006)

  19. 19.

    & Modeling the variable chromosphere of α Orionis. Astrophys. J. 545, 454–474 (2000)

  20. 20.

    & Spatially resolved STIS spectroscopy of α Orionis: evidence for nonradial chromospheric oscillation from detailed modeling. Astrophys. J. 558, 815–829 (2001)

  21. 21.

    Mass motions in the photosphere of Betelgeuse. Astron. J. 135, 1450–1458 (2008)

  22. 22.

    & Atmospheric dynamics and the mass loss process in red supergiant stars. Astron. Astrophys. 469, 671–680 (2007)

  23. 23.

    Validation of the new Hipparcos reduction. Astron. Astrophys. 474, 653–664 (2007)

  24. 24.

    et al. AMBER, the near-infrared spectro-interferometric three-telescope VLTI instrument. Astron. Astrophys. 464, 1–12 (2007)

  25. 25.

    et al. The surface structure and limb-darkening profile of Betelgeuse. Mon. Not. R. Astron. Soc. 290, L11–L16 (1997)

  26. 26.

    et al. The close circumstellar environment of Betelgeuse IV. VLTI/PIONIER interferometric monitoring of the photosphere. Astron. Astrophys. 588, A130 (2016)

  27. 27.

    , , & Radiative hydrodynamics simulations of red supergiant stars. IV. Gray versus non-gray opacities. Astron. Astrophys. 535, A22 (2011)

  28. 28.

    et al. What causes the large extensions of red supergiant atmospheres? Comparison of interferometric observations with 1D hydrostatic, 3D convection, and 1D pulsating model atmospheres. Astron. Astrophys. 575, A50 (2015)

  29. 29.

    & The third signature of granulation in bright-giant and supergiant stars. Astron. J. 143, 92 (2012)

  30. 30.

    et al. The diameters of α Centauri A and B. A comparison of the asteroseismic and VINCI/VLTI views. Astron. Astrophys. 404, 1087–1097 (2003)

  31. 31.

    et al. Interferometric data reduction with AMBER/VLTI. Principle, estimators, and illustration. Astron. Astrophys. 464, 29–42 (2007)

  32. 32.

    et al. Optimised data reduction for the AMBER/VLTI instrument. Astron. Astrophys. 502, 705–709 (2009)

  33. 33.

    Centre to limb darkening of stars. New model and application to stellar interferometry. Astron. Astrophys. 327, 199–206 (1997)

  34. 34.

    . & An Introduction to the Bootstrap (Chapman & Hall, 1993)

  35. 35.

    MIRA: an effective imaging algorithm for optical interferometry. Proc. SPIE 7013, 70131I (2008)

  36. 36.

    et al. Imaging the spinning gas and dust in the disc around the supergiant A[e] star HD 62623. Astron. Astrophys. 526, A107 (2011)

Download references

Acknowledgements

We thank the ESO VLTI team for supporting our VLTI/AMBER observations. This work is based on AMBER observations made with the VLTI of the ESO (program ID: 093.D-0468A/B). K.O. acknowledges the grant from the Universidad Católica del Norte.

Author information

Affiliations

  1. Instituto de Astronomía, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile

    • K. Ohnaka
  2. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

    • G. Weigelt
    •  & K.-H. Hofmann

Authors

  1. Search for K. Ohnaka in:

  2. Search for G. Weigelt in:

  3. Search for K.-H. Hofmann in:

Contributions

K.O. wrote the telescope proposal and the first draft of the paper, carried out the observations, data reduction, and image reconstruction, and worked on data interpretation. G.W. and K.-H.H. were co-authors on the telescope proposal and worked on data reduction and interpretation.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to K. Ohnaka.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature23445

Further reading

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.