Figure 3: Time series obtained during the PRD campaign.
From A terrestrial planet candidate in a temperate orbit around Proxima Centauri
- Guillem Anglada-Escudé1,
- Pedro J. Amado2,
- John Barnes3,
- Zaira M. Berdiñas2,
- R. Paul Butler4,
- Gavin A. L. Coleman1,
- Ignacio de la Cueva5,
- Stefan Dreizler6,
- Michael Endl7,
- Benjamin Giesers6,
- Sandra V. Jeffers6,
- James S. Jenkins8,
- Hugh R. A. Jones9,
- Marcin Kiraga10,
- Martin Kürster11,
- Marίa J. López-González2,
- Christopher J. Marvin6,
- Nicolás Morales2,
- Julien Morin12,
- Richard P. Nelson1,
- José L. Ortiz2,
- Aviv Ofir13,
- Sijme-Jan Paardekooper1,
- Ansgar Reiners6,
- Eloy Rodríguez2,
- Cristina Rodrίguez-López2,
- Luis F. Sarmiento6,
- John P. Strachan1,
- Yiannis Tsapras14,
- Mikko Tuomi9,
- Mathias Zechmeister6,
- Journal name:
- Nature
- Volume:
- 536,
- Pages:
- 437–440
- Date published:
- DOI:
- doi:10.1038/nature19106
a, HARPS-PRD radial velocity measurements. b, c, Quasi-simultaneous photometry from ASH2 for S ii (b) and Hα (c). d, e, Quasi-simultaneous photometry from LCOGT for V (d) and B (e). f, g, Central moments of the mean line profiles for m2 (f) and m3 (g). The solid lines show the best fits. A dashed line indicates a signal that is not sufficiently statistically significant. Excluded measurements that probably affected activity events (for example, flares) are marked with grey arrows. The photometric time series and m2 show evidence of the same approximately 80 d modulation. Error bars correspond to formal 1σ uncertainties.
Additional data
Affiliations
-
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
-
Instituto de Astrofísica de Andalucía – Consejo Superior de Investigaciones Científicas, Glorieta de la Astronomía S/N, E-18008 Granada, Spain
- Pedro J. Amado,
- Zaira M. Berdiñas,
- Marίa J. López-González,
- Nicolás Morales,
- José L. Ortiz,
- Eloy Rodríguez &
- Cristina Rodrίguez-López
-
Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK
- John Barnes
-
Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Road NW, Washington DC 20015, USA
- R. Paul Butler
-
Astroimagen, C. Abad y Lasierra, 58 Bis, 6-2, 07800 Ibiza, Spain
- Ignacio de la Cueva
-
Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Stefan Dreizler,
- Benjamin Giesers,
- Sandra V. Jeffers,
- Christopher J. Marvin,
- Ansgar Reiners,
- Luis F. Sarmiento &
- Mathias Zechmeister
-
McDonald Observatory, the University of Texas at Austin, 2515 Speedway, C1400, Austin, Texas 78712, USA
- Michael Endl
-
Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
- James S. Jenkins
-
Centre for Astrophysics Research, Science & Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB, UK
- Hugh R. A. Jones &
- Mikko Tuomi
-
Warsaw University Observatory, Aleje Ujazdowskie 4, Warszawa, Poland
- Marcin Kiraga
-
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
- Martin Kürster
-
Laboratoire Univers et Particules de Montpellier, Université de Montpellier, Place E. Bataillon—CC 72, 34095 Montpellier Cédex 05, France
- Julien Morin
-
Department of Earth and Planetary Sciences, Weizmann Institute of Science, 234 Herzl Street, Rehovot 76100, Israel
- Aviv Ofir
-
Astronomisches Rechen-Institut, Mönchhofstrasse 12–14, 69120 Heidelberg, Germany
- Yiannis Tsapras
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.
Competing financial interests
The authors declare no competing financial interests.
Reviewer Information
Nature thanks A. Hatzes and D. Queloz for their contribution to the peer review of this work.
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Extended Data Figure 1: Window function.
Hover over figure to zooma–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.
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Extended Data Figure 2: Signal searches on independent radial velocity data sets.
Hover over figure to zooma–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.
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Extended Data Figure 3: Signal searches on the photometry.
Hover over figure to zooma–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.
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Extended Data Figure 4: Signal searches on the width of the spectral lines.
Hover over figure to zooma, 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.
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Extended Data Figure 5: Signal searches on the asymmetry of the spectral lines.
Hover over figure to zooma, 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.
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Extended Data Figure 6: Signal searches on the chromospheric S-index.
Hover over figure to zooma, 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.
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Extended Data Figure 7: Signal searches on the spectroscopic Hα index.
Hover over figure to zooma–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.
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Extended Data Figure 8: Radial velocities and chromospheric emission during a flare.
Hover over figure to zooma–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.
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Extended Data Figure 9: Probability distributions for the activity coefficients versus the signal amplitude.
Hover over figure to zooma–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.
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Extended Data Table 1: Complete set of model parameters
Hover over figure to zoomThe definition of all of the parameters is given in Methods subsection ‘Statistical frameworks and tools’. The values are the maximum a posteriori estimates and the uncertainties are expressed as 68% credibility intervals. The reference epoch for this solution is Julian Date t0 = 2,451,634.73146 d, which corresponds to the first UVES epoch.
*The units of the activity coefficients are metres per second divided by the units of each activity index.
