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A spectrograph for exoplanet observations calibrated at the centimetre-per-second level

Nature volume 485, pages 611–614 (2012)Cite this article

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Abstract

The best spectrographs are limited in stability by their calibration light source1. Laser frequency combs are the ideal calibrators for astronomical spectrographs2. They emit a spectrum of lines that are equally spaced in frequency3 and that are as accurate and stable as the atomic clock relative to which the comb is stabilized. Absolute calibration4 provides the radial velocity of an astronomical object relative to the observer (on Earth). For the detection of Earth-mass exoplanets5,6 in Earth-like orbits around solar-type stars, or of cosmic acceleration7,8,9, the observable is a tiny velocity change of less than 10 cm s−1, where the repeatability of the calibration—the variation in stability across observations—is important. Hitherto, only laboratory systems10,11,12 or spectrograph calibrations of limited performance4,13,14 have been demonstrated. Here we report the calibration of an astronomical spectrograph with a short-term Doppler shift repeatability of 2.5 cm s−1, and use it to monitor the star HD 75289 and recompute the orbit of its planet. This repeatability should make it possible to detect Earth-like planets in the habitable zone of star or even to measure the cosmic acceleration directly.

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Figure 1: Experimental set-up and visualization of the raw data.
Figure 2: Overview over the data taken during the two measurement campaigns in November 2010 and January 2011.
Figure 3: Two-sample deviation of the two long series
Figure 4: Observation of the radial velocity of the star HD 75289 using the LFC for calibration.

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References

  1. Lovis, C. & Pepe, F. A new list of thorium and argon spectral lines in the visible. Astron. Astrophys. 468, 1115–1121 (2007)

    Article  ADS  CAS  Google Scholar 

  2. Murphy, M. T. et al. High-precision wavelength calibration of astronomical spectrographs with laser frequency combs. Mon. Not. R. Astron. Soc. 380, 839–847 (2007)

    Article  ADS  Google Scholar 

  3. Udem, Holzwarth, R. & Hänsch, T. W. Optical frequency metrology. Nature 416, 233–237 (2002)

    Article  ADS  CAS  Google Scholar 

  4. Wilken, T. et al. High-precision calibration of spectrographs. Mon. Not. R. Astron. Soc. 405, L16–L20 (2010)

    Article  ADS  Google Scholar 

  5. Udry, S. et al. The HARPS search for southern extra-solar planets: XI. Super-Earths (5 and 8 M Earth) in a 3-planet system. Astron. Astrophys. 469, L43–L47 (2007)

    Article  ADS  Google Scholar 

  6. Lo Curto, G. et al. The HARPS search for southern extra-solar planets: XXII. Multiple planet systems from the HARPS volume limited sample. Astron. Astrophys. 512, A48 (2010)

    Article  Google Scholar 

  7. Sandage, A. The change of redshift and apparent luminosity of galaxies due to the deceleration of selected expanding universes. Astrophys. J. 136, 319–333 (1962)

    Article  ADS  Google Scholar 

  8. Loeb, A. Direct measurement of cosmological parameters from the cosmic deceleration of extragalactic objects. Astrophys. J. 499, L111–L114 (1998)

    Article  ADS  Google Scholar 

  9. Liske, J. et al. Cosmic dynamics in the era of extremely large telescopes. Mon. Not. R. Astron. Soc. 386, 1192–1218 (2008)

    Article  ADS  CAS  Google Scholar 

  10. Li, C.-H. et al. A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s−1 . Nature 452, 610–612 (2008)

    Article  ADS  CAS  Google Scholar 

  11. Braje, D. A., Kirchner, M. S., Osterman, S., Fortier, T. & Diddams, S. A. Astronomical spectrograph calibration with broad-spectrum frequency combs. Eur. Phys. J. D 48, 57–66 (2008)

    Article  ADS  CAS  Google Scholar 

  12. Quinlan, F., Ycas, G., Osterman, S. & Diddams, S. A. A 12.5 Hz-spaced optical frequency comb spanning >400 nm for near-infrared astronomical spectrograph calibration. Rev. Sci. Instrum. 81, 063105 (2010)

    Article  ADS  CAS  Google Scholar 

  13. Steinmetz, T. et al. Laser frequency combs for astronomical observations. Science 321, 1335–1337 (2008)

    Article  ADS  CAS  Google Scholar 

  14. Benedick, A. J. et al. Visible wavelength astro-comb. Opt. Express 18, 19175–19184 (2010)

    Article  ADS  Google Scholar 

  15. Mayor, M. et al. Setting new standards with HARPS. Messenger 114, 20–24 (2003)

    ADS  Google Scholar 

  16. Baranne, A. et al. ELODIE: a spectrograph for accurate radial velocity measurements. Astron. Astrophys. Suppl. Ser. 119, 373–390 (1996)

    Article  ADS  Google Scholar 

  17. Chang, G. et al. Toward a broadband astro-comb: effects of nonlinear spectral broadening in optical fibers. Opt. Express 18, 12736–12747 (2010)

    Article  ADS  CAS  Google Scholar 

  18. Wilken, T. et al. in Proc. 2011 Conf. Lasers Electro-Optics, paper CWQ2 (IEEE, 2011)

    Google Scholar 

  19. Barnes, J. A. et al. Characterization of frequency stability. IEEE Trans. Instrum. Meas. 20, 105–120 (1971)

    Article  Google Scholar 

  20. Rosenband, T. et al. Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place. Science 319, 1808–1812 (2008)

    Article  ADS  CAS  Google Scholar 

  21. Udry, S. et al. The CORALIE survey for southern extra-solar planets. II. The short-period planetary companions to HD 75289 and HD 130322. Astron. Astrophys. 356, 590–598 (2000)

    ADS  Google Scholar 

  22. Steinmetz, T. et al. Fabry–Perot filter cavities for wide-spaced frequency combs with large spectral bandwidth. Appl. Phys. B 96, 251–256 (2009)

    Article  ADS  CAS  Google Scholar 

  23. Drever, R. W. P. et al. Laser phase and frequency stabilization using an optical resonator. Appl. Phys. B 31, 97–105 (1983)

    Article  ADS  Google Scholar 

  24. Stark, S. et al. 14 GHz visible supercontinuum generation: calibration sources for astronomical spectrographs. Opt. Express 19, 15690–15695 (2011)

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We would like to thank the staff at La Silla Observatory for their support during our campaigns; S. Stark, H. Hundertmark and P. St J. Russell for supplying us with the tapered PCF; C. Lovis, B. Chazelas and F. Pepe for discussions and help with the data reduction; and C. Buggle and A. Thaller for engineering support. T.W.H. acknowledges support from the Max Planck Foundation.

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Authors and Affiliations

  1. Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany ,

    Tobias Wilken, Rafael A. Probst, Tilo Steinmetz, Theodor W. Hänsch, Thomas Udem & Ronald Holzwarth

  2. Menlo Systems GmbH, Am Klopferspitz 19a, D-82152 Martinsried, Germany ,

    Tobias Wilken, Tilo Steinmetz & Ronald Holzwarth

  3. European Southern Observatory, Karl-Schwarzschild-Strasse 3, D-85748 Garching, Germany ,

    Gaspare Lo Curto, Antonio Manescau & Luca Pasquini

  4. Instituto de Astrofísica de Canarias, Calle Via Láctea s/n, E-38205 La Laguna, Spain ,

    Jonay I. González Hernández & Rafael Rebolo

  5. Departamento de Astrofísica, Universidad de La Laguna, La Laguna, E-38206, Spain

    Jonay I. González Hernández & Rafael Rebolo

  6. Consejo Superior de Investigaciones Científicas, Calle Serrano 117, E-28006 La Laguna, Spain ,

    Rafael Rebolo

Authors
  1. Tobias Wilken
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  2. Gaspare Lo Curto
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  9. Theodor W. Hänsch
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  10. Thomas Udem
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  11. Ronald Holzwarth
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Contributions

T.W., R.A.P. and T.S. designed and set up the LFC; T.W., G.L.C., R.A.P., T.S., A.M., L.P., J.I.G.H., T.U. and R.H. participated in data acquisition; T.W., G.L.C., L.P., T.U. and R.H. evaluated and analysed the data; L.P., T.W.H., T.U. and R.H. initiated and supervised the experiment; and T.W. wrote the manuscript. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Tobias Wilken or Ronald Holzwarth.

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The authors declare no competing financial interests.

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Wilken, T., Curto, G., Probst, R. et al. A spectrograph for exoplanet observations calibrated at the centimetre-per-second level. Nature 485, 611–614 (2012). https://doi.org/10.1038/nature11092

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