Galaxy-cluster gravitational lenses can magnify background galaxies by a total factor of up to ~50. Here we report an image of an individual star at redshift z = 1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than ×2,000. A separate image, detected briefly 0.26″ from Lensed Star 1, is probably a counterimage of the first star demagnified for multiple years by an object of 3 solar masses in the cluster. For reasonable assumptions about the lensing system, microlensing fluctuations in the stars’ light curves can yield evidence about the mass function of intracluster stars and compact objects, including binary fractions and specific stellar evolution and supernova models. Dark-matter subhaloes or massive compact objects may help to account for the two images’ long-term brightness ratio.

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We thank the directors of the Space Telescope Science Institute, the Gemini Observatory, the GTC and the European Southern Observatory for granting us discretionary time. We thank B. Katz, D. Kushnir, B. Periello, I. Momcheva, T. Royale, L. Strolger, D. Coe, J. Lotz, M. L. Graham, R. Humphreys, R. Kurucz, A. Dolphin, M. Kriek, S. Rajendran, T. Davis, I. Hubeny, C. Leitherer, F. Nieva, D. Kasen, J. Mauerhan, D. Kelson, J. M. Silverman, A. Oscoz Abaz and Z. Levay for help with the observations and other assistance. The Keck Observatory was made possible with the support of the W. M. Keck Foundation. NASA/STScI grants 14041, 14199, 14208, 14528, 14872 and 14922 provided financial support. P.L.K., A.V.F. and W.Z. are grateful for assistance from the Christopher R. Redlich Fund, the TABASGO Foundation and the Miller Institute for Basic Research in Science (U. C. Berkeley). The work of A.V.F. was completed in part at the Aspen Center for Physics, which is supported by NSF grant PHY-1607611. J.M.D. acknowledges support of projects AYA2015-64508-P (MINECO/FEDER, UE) and AYA2012-39475-C02-01 and the consolider project CSD2010-00064 funded by the Ministerio de Economia y Competitividad. P.G.P.-G. acknowledges support from Spanish government MINECO grants AYA2015-70815-ERC and AYA2015-63650-P. M.O. is supported by JSPS KAKENHI grants 26800093 and 15H05892. M.J. acknowledges support by the Science and Technology Facilities Council (grant ST/L00075X/1). R.J.F. is supported by NSF grant AST-1518052 and Sloan and Packard Foundation fellowships. M.N. acknowledges support from PRIN-INAF-2014 O.G. was supported by NSF Fellowship under award AST-1602595. J.H. acknowledges support from a VILLUM FONDEN Investigator Grant (16599). HST imaging was obtained at https://archive.stsci.edu.

Author information


  1. Department of Astronomy, University of California, Berkeley, CA, USA

    • Patrick L. Kelly
    • , Timothy W. Ross
    • , Alexei V. Filippenko
    •  & Weikang Zheng
  2. School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA

    • Patrick L. Kelly
  3. IFCA, Instituto de Física de Cantabria (UC-CSIC), Santander, Spain

    • Jose M. Diego
  4. Department of Physics and Astronomy, University of South Carolina, Columbia, SC, USA

    • Steven Rodney
  5. Institute for Astronomy, University of Hawaii, Honolulu, HI, USA

    • Nick Kaiser
  6. Department of Theoretical Physics, University of the Basque Country, Bilbao, Spain

    • Tom Broadhurst
  7. IKERBASQUE, Basque Foundation for Science, Alameda Urquijo, Bilbao, Spain

    • Tom Broadhurst
  8. Physics Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel

    • Adi Zitrin
  9. Department of Physics and Astronomy, University of California, Los Angeles, CA, USA

    • Tommaso Treu
    • , Takahiro Morishita
    •  & Xin Wang
  10. Departamento de Astrofísica, Facultad de critical curve. Físicas, Universidad Complutense de Madrid, Madrid, Spain

    • Pablo G. Pérez-González
  11. Astronomical Institute, Tohoku University, Sendai, Japan

    • Takahiro Morishita
  12. Institute for International Advanced Research and Education, Tohoku University, Sendai, Japan

    • Takahiro Morishita
  13. Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, UK

    • Mathilde Jauzac
  14. Institute for Computational Cosmology, Durham University, Durham, UK

    • Mathilde Jauzac
  15. Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, University of KwaZulu-Natal, Durban, South Africa

    • Mathilde Jauzac
  16. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark

    • Jonatan Selsing
    • , Jens Hjorth
    • , Lise Christensen
    •  & Claudio Grillo
  17. Research Center for the Early Universe, University of Tokyo, Tokyo, Japan

    • Masamune Oguri
  18. Department of Physics, University of Tokyo, Tokyo, Japan

    • Masamune Oguri
  19. Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, Kashiwa, Japan

    • Masamune Oguri
  20. Space Telescope Science Institute, Baltimore, MD, USA

    • Laurent Pueyo
    • , Gabriel Brammer
    •  & Adam G. Riess
  21. Miller Institute for Basic Research in Science, University of California, Berkeley, CA, USA

    • Alexei V. Filippenko
  22. Steward Observatory, University of Arizona, Tucson, AZ, USA

    • Nathan Smith
    • , Brenda L. Frye
    •  & Benjamin J. Weiner
  23. Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA

    • S. Bradley Cenko
  24. Joint Space-Science Institute, University of Maryland, College Park, MD, USA

    • S. Bradley Cenko
  25. Las Cumbres Observatory, Goleta, CA, USA

    • D. Andrew Howell
    •  & Curtis McCully
  26. Department of Physics, University of California, Santa Barbara, CA, USA

    • D. Andrew Howell
    •  & Curtis McCully
  27. Univ. Lyon, Univ. Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, Saint-Genis-Laval, France

    • Johan Richard
  28. Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ, USA

    • Saurabh W. Jha
  29. Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, Santa Cruz, CA, USA

    • Ryan J. Foley
  30. Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, USA

    • Colin Norman
    •  & Adam G. Riess
  31. Department of Physics, University of California, Davis, CA, USA

    • Marusa Bradac
  32. Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, Brazil

    • Alberto Molino Benito
  33. Department of Astronomy, University of Geneva, Versoix, Switzerland

    • Antonio Cava
  34. Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam, The Netherlands

    • Selma E. de Mink
  35. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA

    • Or Graur
  36. Department of Astrophysics, American Museum of Natural History, New York, NY, USA

    • Or Graur
  37. Dipartimento di Fisica, Universitá degli Studi di Milano, Milan, Italy

    • Claudio Grillo
  38. Department of Astronomy, Graduate School of Science, The University of Tokyo, Tokyo, Japan

    • Ryota Kawamata
  39. Laboratoire d’Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL), Observatoire de Sauverny, Versoix, Switzerland

    • Jean-Paul Kneib
  40. National Optical Astronomical Observatory, Tucson, AZ, USA

    • Thomas Matheson
  41. INAF, Osservatorio Astronomico di Trieste, Trieste, Italy

    • Mario Nonino
  42. Instituto de Astrofisica de Canarias (IAC), San Cristóbal de La Laguna, Spain

    • Ismael Pérez-Fournon
  43. Universidad de La Laguna, Dpto. Astrofisica, San Cristóbal de La Laguna, Spain

    • Ismael Pérez-Fournon
  44. Dipartimento di Fisica e Scienze della Terra, Universitá degli Studi di Ferrara, Ferrara, Italy

    • Piero Rosati
  45. Leibniz-Institut fur Astrophysik Potsdam (AIP), Potsdam, Germany

    • Kasper Borello Schmidt
  46. University of Michigan, Department of Astronomy, Ann Arbor, MI, USA

    • Keren Sharon


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P.L.K. planned and analysed observations, wrote the manuscript and developed simulations. P.L.K., S.R., P.G.P.-G., T.Ma., M.J., J.S., A.V.F., J.H., D.A.H., S.B.C., B.L.F., M.B., W.Z., G.B., A.M.B., A.C., L.C., C.G., J.-P.K., T.Mo., C.M., M.N., I.P.-F., A.G.R., P.R., K.B.S. and B.J.W. obtained follow-up HST and ground-based imaging. J.M.D. developed microlensing simulations. S.R., T.B., A.Z., T.T., P.G.P.-G., M.J., M.O., A.V.F., N.S., J.H., B.L.F. and S.E.d.M. helped to prepare the manuscript. N.K. interpreted the microlensing events and derived analytic rate formula. T.B., A.Z., T.T., M.J., M.O., X.W., S.W.J., R.J.F., S.E.d.M., O.G. and B.J.W. aided the interpretation. P.G.P.-G. modelled the arc’s SED. T.Mo. modelled the ICL. M.O., J.R., R.K. and K.S. modelled the galaxy cluster. L.P. and C.N. considered the possibility that Icarus could exhibit diffraction effects. T.W.R. analysed the microlensing simulations. N.S. aided interpretation of the star’s SED. X.W. estimated the gas-phase metallicity at Icarus’s location. M.N. extracted photometry of Icarus using a complementary pipeline.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Patrick L. Kelly.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–14, Supplementary Tables 1–4, Supplementary References 1–35 and Supplementary Text.

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