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.

  • Letter
  • Published:

A terrestrial planet candidate in a temperate orbit around Proxima Centauri

Nature volume 536, pages 437–440 (2016)Cite this article

Subjects

Abstract

At a distance of 1.295 parsecs1, the red dwarf Proxima Centauri (α Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun’s closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun2 and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days (ref. 3) and its quiescent activity levels and X-ray luminosity4 are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface5.

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

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

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

Figure 1: Detection of a Doppler signal at 11.2 d.
Figure 2: All of the data sets phase-folded at the 11.2 d signal.
Figure 3: Time series obtained during the PRD campaign.

Similar content being viewed by others

References

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

    Article  ADS  Google Scholar 

  2. Boyajian, T. S. et al. Stellar diameters and temperatures. II: Main-sequence K- and M-stars. Astrophys. J. 757, 112 (2012)

    Article  ADS  Google Scholar 

  3. Kiraga, M. & Stepien, K. Age–rotation–activity relations for M dwarf stars. Acta Astron. 57, 149–172 (2007)

    ADS  Google Scholar 

  4. Güdel, M., Audard, M., Reale, F., Skinner, S. L. & Linsky, J. L. Flares from small to large: X-ray spectroscopy of Proxima Centauri with XMM-Newton. Astron. Astrophys. 416, 713–732 (2004)

    Article  ADS  CAS  Google Scholar 

  5. Kopparapu, R. K. et al. Habitable zones around main-sequence stars: new estimates. Astrophys. J. 765, 131 (2013)

    Article  ADS  CAS  Google Scholar 

  6. Pepe, F. et al. The HARPS search for Earth-like planets in the habitable zone. I. Very low-mass planets around HD 20794, HD 85512, and HD 192310. Astron. Astrophys. 534, A58 (2011)

    Article  Google Scholar 

  7. Anglada-Escudé, G. & Butler, R. P. The HARPS-TERRA Project. I: description of the algorithms, performance, and new measurements on a few remarkable stars observed by HARPS. Astrophys. J. Suppl. Ser. 200, 15 (2012)

    Article  ADS  Google Scholar 

  8. Butler, R. P. et al. Attaining Doppler precision of 3 m s−1. Publ. Astron. Soc. Pacif. 108, 500–509 (1996)

    Article  ADS  Google Scholar 

  9. Kürster, M. et al. The low-level radial velocity variability in Barnard’s star (= GJ 699): secular acceleration, indications for convective redshift, and planet mass limits. Astron. Astrophys. 403, 1077–1087 (2003)

    Article  ADS  CAS  Google Scholar 

  10. Arriagada, P. et al. Two planetary companions around the K7 dwarf GJ 221: a hot super-Earth and a candidate in the sub-Saturn desert range. Astrophys. J. 771, 42 (2013)

    Article  ADS  CAS  Google Scholar 

  11. Berdiñas, Z. M., Amado, P. J., Anglada-Escudé, G., Rodríguez-López, C. & Barnes, J. High-cadence spectroscopy of M-dwarfs. I: analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B. Mon. Not. R. Astron. Soc. 459, 3551B (2016)

    Article  ADS  Google Scholar 

  12. Sicardy, B. et al. A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation. Nature 478, 493–496 (2011)

    Article  ADS  CAS  PubMed  Google Scholar 

  13. Brown, T. M. et al. Las Cumbres Observatory Global Telescope Network. Publ. Astron. Soc. Pacific 125, 1031–1055 (2013)

    Article  ADS  Google Scholar 

  14. Baluev, R. V. The impact of red noise in radial velocity planet searches: only three planets orbiting GJ 581? Mon. Not. R. Astron. Soc. 429, 2052–2068 (2013)

    Article  ADS  Google Scholar 

  15. Tuomi, M., Jones, H. R. A., Barnes, J. R., Anglada-Escudé, G. & Jenkins, J. S. Bayesian search for low-mass planets around nearby M dwarfs—estimates for occurrence rate based on global detectability statistics. Mon. Not. R. Astron. Soc. 441, 1545–1569 (2014)

    Article  ADS  Google Scholar 

  16. Haario, H., Laine, M., Mira, A. & Saksman, E. Dram: efficient adaptive MCMC. Stat. Comput. 16, 339–354 (2006)

    Article  MathSciNet  Google Scholar 

  17. Rajpaul, V., Aigrain, S. & Roberts, S. Ghost in the time series: no planet for Alpha Cen B. Mon. Not. R. Astron. Soc. 456, L6–L10 (2016)

    Article  ADS  Google Scholar 

  18. Bonfils, X. et al. The HARPS search for southern extra-solar planets. X: A msini = 11M⊕ planet around the nearby spotted M dwarf GJ 674. Astron. Astrophys. 474, 293–299 (2007)

    Article  ADS  CAS  Google Scholar 

  19. Barnes, J. R. et al. Precision radial velocities of 15 M5–M9 dwarfs. Mon. Not. R. Astron. Soc. 439, 3094–3113 (2014)

    Article  ADS  CAS  Google Scholar 

  20. Ofir, A. Optimizing the search for transiting planets in long time series. Astron. Astrophys. 561, A138 (2014)

    Article  ADS  Google Scholar 

  21. Kopparapu, R. k. et al. The inner edge of the habitable zone for synchronously rotating planets around low-mass stars using general circulation models. Astrophys. J. 819, 84 (2016)

    Article  ADS  Google Scholar 

  22. Reiners, A. & Basri, G. The moderate magnetic field of the flare star Proxima Centauri. Astron. Astrophys. 489, L45–L48 (2008)

    Article  ADS  CAS  Google Scholar 

  23. Vidotto, A. A. et al. Effects of M dwarf magnetic fields on potentially habitable planets. Astron. Astrophys. 557, A67 (2013)

    Article  Google Scholar 

  24. Zuluaga, J. I., Bustamante, S., Cuartas, P. A. & Hoyos, J. H. The influence of thermal evolution in the magnetic protection of terrestrial planets. Astrophys. J. 770, 23 (2013)

    Article  ADS  Google Scholar 

  25. Bolmont, E. et al. Water loss from Earth-sized planets in the habitable zones of ultracool dwarfs: implications for the planets of TRAPPIST-1. Preprint at http://arxiv.org/abs/1605.00616 (2016)

  26. Tanaka, H., Takeuchi, T. & Ward, W. R. Three-dimensional interaction between a planet and an isothermal gaseous disk. I: corotation and Lindblad torques and planet migration. Astrophys. J. 565, 1257–1274 (2002)

    Article  ADS  Google Scholar 

  27. Weidenschilling, S. J. Aerodynamics of solid bodies in the solar nebula. Mon. Not. R. Astron. Soc. 180, 57–70 (1977)

    Article  ADS  Google Scholar 

  28. Snellen, I. et al. Combining high-dispersion spectroscopy with high contrast imaging: probing rocky planets around our nearest neighbors. Astron. Astrophys. 576, A59 (2015)

    Article  Google Scholar 

  29. Lubin, P. A roadmap to interstellar flight. Preprint at http://arxiv.org/abs/1604.01356 (2016)

  30. Delfosse, X. et al. Accurate masses of very low mass stars. IV. Improved mass-luminosity relations. Astron. Astrophys. 364, 217–224 (2000)

    ADS  Google Scholar 

  31. Haario, H., Saksman, E. & Tamminen, J. An adaptive Metropolis algorithm. Bernouilli 7, 223 (2001)

    Article  MathSciNet  MATH  Google Scholar 

  32. Tuomi, M. et al. Signals embedded in the radial velocity noise: periodic variations in the τ Ceti velocities. Astron. Astrophys. 551, A79 (2013)

    Article  Google Scholar 

  33. Metropolis, N., Rosenbluth, A., Rosenbluth, M., Teller, A. & Teller, E. Equations of state valculations by fast computing machines. J. Chem. Phys. 21, 1087–1092 (1953)

    Article  ADS  CAS  Google Scholar 

  34. Hastings, W. K. Monte Carlo sampling methods using Markov chains and their applications. Biometrika 57, 97–109 (1970)

    Article  MathSciNet  MATH  Google Scholar 

  35. Newton, M. A. & Raftery, A. E. Approximate Bayesian inference with the weighted likelihood bootstrap. J. R. Stat.Soc. B 56, 3–48 (1994)

    MathSciNet  MATH  Google Scholar 

  36. Tuomi, M. A new cold sub-Saturnian candidate planet orbiting GJ 221. Mon. Not. R. Astron. Soc. 440, L1–L5 (2014)

    Article  ADS  Google Scholar 

  37. Wright, J. T. & Howard, A. W. Efficient fitting of multiplanet Keplerian models to radial velocity and astrometry data. Astrophys. J. Suppl. Ser. 182, 205–215 (2009)

    Article  ADS  Google Scholar 

  38. Scargle, J. D. Studies in astronomical time series analysis. I: modeling random processes in the time domain. Astrophys. J. Suppl. Ser. 45, 1–71 (1981)

    Article  ADS  MathSciNet  Google Scholar 

  39. Tuomi, M. Evidence for nine planets in the HD 10180 system. Astron. Astrophys. 543, A52 (2012)

    Article  ADS  Google Scholar 

  40. Tuomi, M. & Anglada-Escudé, G. Up to four planets around the M dwarf GJ 163: sensitivity of Bayesian planet detection criteria to prior choice. Astron. Astrophys. 556, A111 (2013)

    Article  ADS  Google Scholar 

  41. Berger, J. O. Statistical Decision Theory and Bayesian Analysis Section 3.3 (Springer, 1980)

  42. Anglada-Escudé, G. et al. A dynamically-packed planetary system around GJ 667C with three super-Earths in its habitable zone. Astron. Astrophys. 556, A126 (2013)

    Article  Google Scholar 

  43. Lomb, N. R. Least-squares frequency analysis of unequally spaced data. Astrophys. Space Sci. 39, 447–462 (1976)

    Article  ADS  Google Scholar 

  44. Scargle, J. D. Studies in astronomical time series analysis. II: statistical aspects of spectral analysis of unevenly spaced data. Astrophys. J. 263, 835–853 (1982)

    Article  ADS  Google Scholar 

  45. Zechmeister, M., Kürster, M. & Endl, M. The M dwarf planet search programme at the ESO VLT + UVES: a search for terrestrial planets in the habitable zone of M dwarfs. Astron. Astrophys. 505, 859–871 (2009)

    Article  ADS  Google Scholar 

  46. Cumming, A. Detectability of extrasolar planets in radial velocity surveys. Mon. Not. R. Astron. Soc. 354, 1165–1176 (2004)

    Article  ADS  Google Scholar 

  47. Ferraz-Mello, S. Estimation of periods from unequally spaced observations. Astron. J. 86, 619–624 (1981)

    Article  ADS  Google Scholar 

  48. Baluev, R. V. Accounting for velocity jitter in planet search surveys. Mon. Not. R. Astron. Soc. 393, 969–978 (2009)

    Article  ADS  CAS  Google Scholar 

  49. Endl, M. & Kürster, M. Toward detection of terrestrial planets in the habitable zone of our closest neighbor: Proxima Centauri. Astron. Astrophys. 488, 1149–1153 (2008)

    Article  ADS  Google Scholar 

  50. Bonfils, X. et al. The HARPS search for southern extra-solar planets. XXXI: the M-dwarf sample. Astron. Astrophys. 549, A109 (2013)

    Article  CAS  Google Scholar 

  51. Queloz, D. et al. No planet for HD 166435. Astron. Astrophys. 379, 279–287 (2001)

    Article  ADS  CAS  Google Scholar 

  52. Robertson, P., Mahadevan, S., Endl, M. & Roy, A. Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581. Science 345, 440–444 (2014)

    Article  ADS  CAS  PubMed  Google Scholar 

  53. Donati, J.-F. & Brown, S. F. Zeeman–Doppler imaging of active stars. V: sensitivity of maximum entropy magnetic maps to field orientation. Astron. Astrophys. 326, 1135–1142 (1997)

    ADS  Google Scholar 

  54. Barnes, J. R. et al. Red Optical Planet Survey: a new search for habitable Earths in the southern sky. Mon. Not. R. Astron. Soc. 424, 591–604 (2012)

    Article  ADS  Google Scholar 

  55. Press, W. H., Teukolsky, S. A., Vetterling, W. T. & Flannery, B. P. Numerical Recipes in FORTRAN. The Art of Scientific Computing 2nd edn, Section 4.1 (Cambridge Univ. Press, 1992)

  56. Jenkins, J. S. et al. An activity catalogue of southern stars. Mon. Not. R. Astron. Soc. 372, 163–173 (2006)

    Article  ADS  CAS  Google Scholar 

  57. Jenkins, J. S. et al. Metallicities and activities of southern stars. Astron. Astrophys. 485, 571–584 (2008)

    Article  ADS  CAS  Google Scholar 

  58. Collins, K. A., Kielkopf, J. F. & Stassun, K. G. AstroImageJ: image processing and photometric extraction for ultra-precise astronomical light curves. Preprint at http://arxiv.org/abs/1601.02622 (2016)

  59. Southworth, J. et al. High-precision photometry by telescope defocussing. VI: WASP-24, WASP-25 and WASP-26. Mon. Not. R. Astron. Soc. 444, 776–789 (2014)

    Article  ADS  Google Scholar 

  60. Dawson, R. I. & Fabrycky, D. C. Radial velocity planets de-aliased: a new, short period for super-Earth 55 Cnc e. Astrophys. J. 722, 937–953 (2010)

    Article  ADS  Google Scholar 

  61. Aigrain, S., Pont, F. & Zucker, S. A simple method to estimate radial velocity variations due to stellar activity using photometry. Mon. Not. R. Astron. Soc. 419, 3147–3158 (2012)

    Article  ADS  Google Scholar 

  62. Gomes da Silva, J. et al. Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program. II: activity and radial velocity. Astron. Astrophys. 541, A9 (2012)

    Article  CAS  Google Scholar 

  63. Baliunas, S. L. et al. Chromospheric variations in main-sequence stars. Astrophys. J. 438, 269–287 (1995)

    Article  ADS  CAS  Google Scholar 

  64. Pascual-Granado, J., Garrido, R. & Suárez, J. C. Limits in the application of harmonic analysis to pulsating stars. Astron. Astrophys. 581, A89 (2015)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

We thank E. Gerlach, R. Street and U. Seemann for their support to the science preparations. We thank P. Micakovic, M. M. Mutter (QMUL), R. Ivison, G. Hussain, I. Saviane, O. Sandu, L. L. Christensen, R. Hook and the personnel at La Silla (ESO) for making the PRD campaign possible. The authors acknowledge support from the following funding grants: Leverhulme Trust/UK RPG-2014-281 (H.R.A.J., G.A.-E. and M.T.); MINECO/Spain AYA-2014-54348-C3-1-R (P.J.A., C.R.-L., Z.M.B. and E.R.); MINECO/Spain ESP2014-54362-P (M.J.L.-G.); MINECO/Spain AYA-2014-56637-C2-1-P (J.L.O. and N.M.); J.A./Spain 2012-FQM1776 (J.L.O. and N.M.); CATA-Basal/Chile PB06 Conicyt (J.S.J.); Fondecyt/Chile project #1161218 (J.S.J.); STFC/UK ST/M001008/1 (R.P.N., G.A.L.C. and G.A.-E.); STFC/UK ST/L000776/1 (J.B.); ERC/EU Starting Grant #279347 (A.R., L.F.S. and S.V.J.); DFG/Germany Research Grants RE 1664/9-2 (A.R.); RE 1664/12-1 (M.Z.); DFG/Germany Colloborative Research Center 963 (C.J.M. and S.D.); DFG/Germany Research Training Group 1351 (L.F.S.); and NSF/USA grant AST-1313075 (M.E.). Study based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programmes 096.C-0082 and 191.C-0505. Observations were obtained with ASH2, which is supported by the Instituto de Astrofísica de Andalucía and Astroimagen. This work makes use of observations from the LCOGT network. We acknowledge the effort of the UVES/M-dwarf and the HARPS/Geneva teams, who obtained a substantial amount of the data used in this work.

Author information

Authors and Affiliations

  1. School of Physics and Astronomy, Queen Mary University of London, 327 Mile End Road, London, E1 4NS, UK

    Guillem Anglada-Escudé, Gavin A. L. Coleman, Richard P. Nelson, Sijme-Jan Paardekooper & John P. Strachan

  2. Instituto de Astrofísica de Andalucía – Consejo Superior de Investigaciones Científicas, Glorieta de la Astronomía S/N, Granada, E-18008, Spain

    Pedro J. Amado, Zaira M. Berdiñas, Marίa J. López-González, Nicolás Morales, José L. Ortiz, Eloy Rodríguez & Cristina Rodrίguez-López

  3. Department of Physical Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA, UK

    John Barnes

  4. Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, 20015, Washington DC, USA

    R. Paul Butler

  5. Astroimagen, C. Abad y Lasierra, 58 Bis, Ibiza, 6-2, 07800, Spain

    Ignacio de la Cueva

  6. Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, Göttingen, 37077, Germany

    Stefan Dreizler, Benjamin Giesers, Sandra V. Jeffers, Christopher J. Marvin, Ansgar Reiners, Luis F. Sarmiento & Mathias Zechmeister

  7. McDonald Observatory, the University of Texas at Austin, 2515 Speedway, C1400, Austin, 78712, Texas, USA

    Michael Endl

  8. Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile

    James S. Jenkins

  9. Centre for Astrophysics Research, Science & Technology Research Institute, University of Hertfordshire, Hatfield, AL10 9AB, UK

    Hugh R. A. Jones & Mikko Tuomi

  10. Warsaw University Observatory, Aleje Ujazdowskie 4, Warszawa, Poland

    Marcin Kiraga

  11. Max-Planck-Institut für Astronomie, Königstuhl 17, Heidelberg, 69117, Germany

    Martin Kürster

  12. Laboratoire Univers et Particules de Montpellier, Université de Montpellier, Place E. Bataillon—CC 72, Montpellier, 34095, Cédex 05, France

    Julien Morin

  13. Department of Earth and Planetary Sciences, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 76100, Israel

    Aviv Ofir

  14. Astronomisches Rechen-Institut, Mönchhofstrasse 12–14, Heidelberg, 69120, Germany

    Yiannis Tsapras

Authors
  1. Guillem Anglada-Escudé
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Pedro J. Amado
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. John Barnes
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Zaira M. Berdiñas
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. R. Paul Butler
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Gavin A. L. Coleman
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Ignacio de la Cueva
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Stefan Dreizler
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Michael Endl
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Benjamin Giesers
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Sandra V. Jeffers
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. James S. Jenkins
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Hugh R. A. Jones
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. Marcin Kiraga
    View author publications

    You can also search for this author in PubMed Google Scholar

  15. Martin Kürster
    View author publications

    You can also search for this author in PubMed Google Scholar

  16. Marίa J. López-González
    View author publications

    You can also search for this author in PubMed Google Scholar

  17. Christopher J. Marvin
    View author publications

    You can also search for this author in PubMed Google Scholar

  18. Nicolás Morales
    View author publications

    You can also search for this author in PubMed Google Scholar

  19. Julien Morin
    View author publications

    You can also search for this author in PubMed Google Scholar

  20. Richard P. Nelson
    View author publications

    You can also search for this author in PubMed Google Scholar

  21. José L. Ortiz
    View author publications

    You can also search for this author in PubMed Google Scholar

  22. Aviv Ofir
    View author publications

    You can also search for this author in PubMed Google Scholar

  23. Sijme-Jan Paardekooper
    View author publications

    You can also search for this author in PubMed Google Scholar

  24. Ansgar Reiners
    View author publications

    You can also search for this author in PubMed Google Scholar

  25. Eloy Rodríguez
    View author publications

    You can also search for this author in PubMed Google Scholar

  26. Cristina Rodrίguez-López
    View author publications

    You can also search for this author in PubMed Google Scholar

  27. Luis F. Sarmiento
    View author publications

    You can also search for this author in PubMed Google Scholar

  28. John P. Strachan
    View author publications

    You can also search for this author in PubMed Google Scholar

  29. Yiannis Tsapras
    View author publications

    You can also search for this author in PubMed Google Scholar

  30. Mikko Tuomi
    View author publications

    You can also search for this author in PubMed Google Scholar

  31. Mathias Zechmeister
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

In the author list, after G.A.-E., the authors are listed in alphabetical order. G.A.-E. led the PRD campaign, observing proposals and organized the manuscript. P.J.A. led observing proposals and organized and supported the Instituto de Astrofisica de Andalucía team through research grants. M.T. obtained the early signal detections and most of the Bayesian analyses. J.S.J., J.B., Z.M.B. and H.R.A.J. participated in the analyses and obtained activity measurements. Z.M.B. also led observing proposals. H.R.A.J. funded several co-authors via research grants. M. Kuerster and M.E. provided the extracted UVES spectra, and R.P.B. re-derived radial velocity measurements. C.R.-L. coordinated photometric follow-up campaigns. E.R. led the ASH2 team and related reductions (M.J.L.-G., I.d.l.C., J.L.O. and N.M.). Y.T. led the LCOGT proposals, campaign and reductions. M.Z. obtained observations and performed analyses on HARPS and UVES spectra. A.O. analysed time series and transit searches. J.M., S.V.J. and A.R. analysed stellar activity data. A.R. funded several co-authors via research grants. R.P.N., G.A.L.C., S.-J.P., S.D. and B.G. did dynamical studies and studied the planet formation context. M. Kiraga provided early access to time series from the ASAS survey. C.J.M. and L.F.S. participated in the HARPS campaigns. All authors contributed to the preparation of observing proposals and the manuscript.

Corresponding author

Correspondence to Guillem Anglada-Escudé.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Reviewer Information

Nature thanks A. Hatzes and D. Queloz for their contribution to the peer review of this work.

Extended data figures and tables

Extended Data Figure 1 Window function.

a–c, Window function of the UVES (a), HARPS pre-2016 (b) and HARPS PRD (c) data sets. The same window function applies to the time series of Doppler and activity data. Peaks in the window function are periods at which aliases of infinite period signals would be expected. The green vertical lines mark the period of the planet candidate at 11.2 d.

Extended Data Figure 2 Signal searches on independent radial velocity data sets.

a–c, Likelihood-ratio periodograms searches on the radial velocity (RV) measurements of the UVES (a), HARPS pre-2016 (b) and HARPS PRD (c) subsets. The periodogram with all three sets combined is shown in Fig. 1. The black and red lines represent the searches for the first and second signals, respectively. The green vertical lines mark the period of the planet candidate at 11.2 d.

Extended Data Figure 3 Signal searches on the photometry.

a–d, Likelihood-ratio periodograms searches for signals in each photometric ASH2 photometric band (a, b) and LCOGT bands (c, d). The two sinusoid fits to the ASH2 S ii series (P1 = 84 d, P2 = 39.1 d) are used later to construct the FF′ model to test for correlations of the photometry with the radial velocity data. The black, red and blue lines represent the search for the first, second and third signal respectively. The green vertical lines mark the period of the planet candidate at 11.2 d.

Extended Data Figure 4 Signal searches on the width of the spectral lines.

a, b, Likelihood-ratio periodogram searches on the width of the mean spectral line as measured by m2 for the HARPS pre-2016 (a) and HARPS PRD data (b). The signals in the HARPS pre-2016 data are comparable to the photometric period reported in the literature and the variability in the HARPS PRD run compares quite well to the photometric variability. The black, red and blue lines represent the search for the first, second and third signal, respectively. The green vertical lines mark the period of the planet candidate at 11.2 d.

Extended Data Figure 5 Signal searches on the asymmetry of the spectral lines.

a, b, Likelihood-ratio periodogram searches on the line asymmetry as measured by m3 from the HARPS pre-2016 (a) and HARPS PRD (b) data sets. Signal beating at around 1 yr and 0.5 yr is detected in the HARPS pre-2016 data, which is possibly related to instrumental systematic effects or telluric contamination. No signals are detected above the 1% threshold in the HARPS PRD campaign. The black and red lines represent the search for the first and second signals respectively. The green vertical lines mark the period of the planet candidate at 11.2 d.

Extended Data Figure 6 Signal searches on the chromospheric S-index.

a, b, Likelihood-ratio periodogram of the S-index from the HARPS pre-2016 (a) and HARPS PRD (b) campaigns. No signals were detected above the 1% threshold. The green vertical lines mark the period of the planet candidate at 11.2 d.

Extended Data Figure 7 Signal searches on the spectroscopic Hα index.

a–c, Likelihood-ratio periodogram searches of Hα intensity from the UVES (a), HARPS pre-2016 (b) and HARPS PRD (c) campaigns. No signals were detected above the 1% threshold. The green vertical lines mark the period of the planet candidate at 11.2 d.

Extended Data Figure 8 Radial velocities and chromospheric emission during a flare.

a–d, Radial velocities (a) and equivalent width measurements of the Hα (b), Na doublet lines (c) and the S-index (d) as a function of time during a flare that occurred the night of 5 May 2013. The time axis is days since jd = 245417.0 d. No trace of the flare is observed in the radial velocities. Error bars in the radial velocities correspond to 1σ errors. The formal 1σ errors in the equivalent width measurements are comparable to the size of the points.

Extended Data Figure 9 Probability distributions for the activity coefficients versus the signal amplitude.

a–n, Marginalized posterior densities of the activity coefficients versus the semi-amplitude of the signal for UVES (a), HARPS pre-2016 (b–f), HARPS PRD campaign (g–k) and the photometric FF′ indices for the PRD campaign only (l–n). Each panel shows equiprobability contours containing 50%, 95% and 99% of the probability density around the mean estimate, and the corresponding standard deviation of the marginalized distribution (1σ) in red. The blue bar shows the zero value of each activity coefficient. Only CF′ is found to be substantially different from zero.

Extended Data Table 1 Complete set of model parameters
Full size table

Related audio

Supplementary information

Supplementary Data

This zipped file contains the time-series used in the paper. All time-series are given as plain ASCII/CSV files (columns separated by commas) and follow the same format. See the README file within the zip folder for details. (ZIP 62 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Anglada-Escudé, G., Amado, P., Barnes, J. et al. A terrestrial planet candidate in a temperate orbit around Proxima Centauri. Nature 536, 437–440 (2016). https://doi.org/10.1038/nature19106

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature19106

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

Advanced 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