A

A study in scarlet

Astronomy and Astrophysics, vol. 695, pp. A42

Abstract

Aims. We investigate the photometric characteristics of a sample of intermediate-luminosity red transients (ILRTs), a class of elusive objects with peak luminosity between that of classical novae and standard supernovae. Our goal is to provide a stepping stone in the path to reveal the physical origin of such events, thanks to the analysis of the datasets collected. Methods. We present the multi-wavelength photometric follow-up of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd, and AT 2019udc. Through the analysis and modelling of their spectral energy distribution and bolometric light curves, we inferred the physical parameters associated with these transients. Results. All four objects display a single-peaked light curve which ends in a linear decline in magnitudes at late phases. A flux excess with respect to a single blackbody emission is detected in the infrared domain for three objects in our sample, a few months after maximum. This feature, commonly found in ILRTs, is interpreted as a sign of dust formation. Mid-infrared monitoring of NGC 300 2008OT-1 761 days after maximum allowed us to infer the presence of ∼10−3–10−5 M⊙ of dust, depending on the chemical composition and the grain size adopted. The late-time decline of the bolometric light curves of the considered ILRTs is shallower than expected for 56Ni decay, hence requiring an additional powering mechanism. James Webb Space Telescope observations of AT 2019abn prove that the object has faded below its progenitor luminosity in the mid-infrared domain, five years after its peak. Together with the disappearance of NGC 300 2008OT-1 in Spitzer images seven years after its discovery, this supports the terminal explosion scenario for ILRTs. With a simple semi-analytical model we tried to reproduce the observed bolometric light curves in the context of a few solar masses ejected at few 103 km s−1 and enshrouded in an optically thick circumstellar medium.

Authors 59

  1. G. Valerin corresponding

    Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  2. Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  3. Brera Astronomical Observatory · Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  4. Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  5. Chinese Academy of Sciences · Yunnan Observatories

    Affiliation as printed

    International Centre of Supernovae, Yunnan Key Laboratory Kunming 650216, PR China

    Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650216, P.R. China

    Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216, PR China

  6. National Central University

    Affiliation as printed

    Graduate Institute of Astronomy, National Central University, 300 Jhongda Road, 32001 Jhongli, Taiwan

  7. Radboud University Nijmegen · Space Research Organisation Netherlands

    Affiliation as printed

    Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010 6500 GL, Nijmegen, The Netherlands

    SRON, Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA, Leiden, The Netherlands

  8. Institute of Space Sciences · Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

    Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans s/n, E-08193 Barcelona, Spain

  9. University College Dublin

    Affiliation as printed

    School of Physics, O’Brien Centre for Science North, University College Dublin, Belfield, Dublin 4, Ireland

  10. Hiroshima University · Stockholm University · AlbaNova

    Affiliation as printed

    Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Japan

    The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm, Sweden

  11. Florida State University

    Affiliation as printed

    Department of Physics, Florida State University, 77 Chieftan Way, Tallahassee, FL 32306, USA

  12. Las Cumbres Observatory Global Telescope Network · University of California, Santa Barbara

    Affiliation as printed

    Department of Physics, University of California, Santa Barbara, CA 93106, USA

    Las Cumbres Observatory, 6740 Cortona Dr. Suite 102, Goleta, CA 93117, USA

  13. Cardiff University

    Affiliation as printed

    School of Physics & Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA, UK

  14. University of Copenhagen · Astronomical Observatory of Capodimonte · National Institute for Astrophysics

    Affiliation as printed

    DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen, Denmark

    INAF, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli, Italy

    Københavns Universitet, Faculty of Science, Niels Bohr Institute, DARK, DK

  15. California Institute of Technology

    Affiliation as printed

    Caltech, Mail Code 220-6, Pasadena, CA 91125, USA

  16. University of Turku

    Affiliation as printed

    Tuorla Observatory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland

  17. University of Turku

    Affiliation as printed

    Tuorla Observatory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland

  18. Max Planck Institute for Astrophysics · Liverpool John Moores University

    Affiliation as printed

    Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK

    Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Str. 1, D-85748 Garching, Germany

  19. Aryabhatta Research Institute of Observational Sciences

    Affiliation as printed

    Aryabhatta Research Institute of observational sciences, Manora Peak, Nainital 263001, India

  20. University of Tarapacá

    Affiliation as printed

    Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica, Chile

  21. Trinity College Dublin

    Affiliation as printed

    School of Physics, Trinity College Dublin, College Green, Dublin 2, Ireland

  22. University of Arizona

    Affiliation as printed

    Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA

  23. Queen's University Belfast · University of Oxford

    Affiliation as printed

    Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast Belfast BT7 1NN, UK,

    Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK

  24. Aarhus University

    Affiliation as printed

    Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark

    Aarhus University, Natural Sciences, Department of Physics and Astronomy, DK

  25. Collurania Teramo Observatory · National Institute for Astrophysics

    Affiliation as printed

    INAF – Osservatorio Astronomico d’Abruzzo, via M. Maggini snc, Teramo I-64100, Italy

  26. University of California, Davis

    Affiliation as printed

    Department of Physics, University of California, Davis, CA 95616, USA

  27. Millennium Institute of Astrophysics · European Southern Observatory

    Affiliation as printed

    European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago, Chile

    Millennium Institute of Astrophysics, Nuncio Monsenor Sótero Sanz 100, Providencia, 8320000 Santiago, Chile

  28. University of Arizona

    Affiliation as printed

    Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA

  29. University of Arizona

    Affiliation as printed

    Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA

  30. Stockholm University · AlbaNova

    Affiliation as printed

    The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm, Sweden

  31. Osservatorio Astrofisico di Catania

    Affiliation as printed

    INAF-Osservatorio Astrofisico di Catania, Via Santa Sofia 78, I-95123 Catania, Italy

  32. Stockholm University · AlbaNova

    Affiliation as printed

    The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm, Sweden

  33. Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  34. Universidad Andrés Bello · Millennium Institute of Astrophysics

    Affiliation as printed

    Instituto de Astrofísica, Universidad Andres Bello, Fernandez Concha 700, Las Condes, Santiago RM, Chile

    Millennium Institute of Astrophysics, Nuncio Monsenor Sótero Sanz 100, Providencia, 8320000 Santiago, Chile

  35. Astronomical Observatory of Capodimonte · International Center for Relativistic Astrophysics · National Institute for Astrophysics

    Affiliation as printed

    ICRANet, Piazza della Repubblica 10, I-65122 Pescara, Italy

    INAF, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli, Italy

  36. Goethe University Frankfurt · Istituto Nazionale di Fisica Nucleare, Trento Institute for Fundamental Physics And Applications · Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

    INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, I-38123 Trento, Italy

    Institut für Theoretische Physik, Goethe Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany

  37. Queen's University Belfast

    Affiliation as printed

    Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast Belfast BT7 1NN, UK,

  38. Institute of Space Sciences · Institut d'Estudis Espacials de Catalunya

    Affiliation as printed

    Institut d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Spain

    Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans s/n, E-08193 Barcelona, Spain

  39. University of Turku

    Affiliation as printed

    Tuorla Observatory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland

  40. Florida State University · Las Cumbres Observatory Global Telescope Network · Center for Astrophysics Harvard & Smithsonian · The NSF AI Institute for Artificial Intelligence and Fundamental Interactions

    Affiliation as printed

    Center for Astrophysics, Harvard & Smithsonian, Cambridge, Massachusetts, MA 02138, USA

    Department of Physics, Florida State University, 77 Chieftan Way, Tallahassee, FL 32306, USA

    Las Cumbres Observatory, 6740 Cortona Dr. Suite 102, Goleta, CA 93117, USA

    The NSF AI Institute for Artificial Intelligence and Fundamental Interactions, 77 Massachusetts Avenue, Cambridge, USA

  41. Stockholm University · Aarhus University · AlbaNova

    Affiliation as printed

    Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark

    The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm, Sweden

    Aarhus University, Natural Sciences, Department of Physics and Astronomy, DK

  42. University of Turku

    Affiliation as printed

    Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland

    Tuorla Observatory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland

  43. DTU Space · Technical University of Denmark

    Affiliation as printed

    DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, 2800Kgs. Lyngby, Denmark

    Technical University of Denmark, Department of Space Research and Technology, DK

  44. University of Arizona

    Affiliation as printed

    Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA

  45. Las Cumbres Observatory Global Telescope Network

    Affiliation as printed

    Las Cumbres Observatory, 6740 Cortona Dr. Suite 102, Goleta, CA 93117, USA

  46. Institute of Space Sciences · Institut d'Estudis Espacials de Catalunya

    Affiliation as printed

    Institut d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Spain

    Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans s/n, E-08193 Barcelona, Spain

  47. Queen's University Belfast

    Affiliation as printed

    Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast Belfast BT7 1NN, UK,

  48. University of Padua · Osservatorio Astronomico di Padova

    Affiliation as printed

    Dipartimento di Fisica e Astronomia “G. Galilei”, Università degli studi di Padova Vicolo dell’Osservatorio 3, I-35122 Padova, Italy

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  49. Las Cumbres Observatory Global Telescope Network · University of California, Santa Barbara

    Affiliation as printed

    Department of Physics, University of California, Santa Barbara, CA 93106, USA

    Las Cumbres Observatory, 6740 Cortona Dr. Suite 102, Goleta, CA 93117, USA

  50. National Observatory of Athens · Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing

    Affiliation as printed

    IAASARS, National Observatory of Athens, Metaxa & Vas. Pavlou St., 15236 Penteli, Athens, Greece

  51. University of Virginia

    Affiliation as printed

    Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA

  52. Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany

  53. University of North Carolina at Chapel Hill

    Affiliation as printed

    Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA

  54. Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  55. Indian Institute of Astrophysics

    Affiliation as printed

    Indian Institute Of Astrophysics, 100 Feet Rd, Santhosapuram, 2nd Block, Koramangala, Bengaluru, Karnataka 560034, India

  56. Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  57. Osservatorio Astronomico di Padova

    Affiliation as printed

    INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy

  58. University of Arizona

    Affiliation as printed

    Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA

  59. Queen's University Belfast

    Affiliation as printed

    Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast Belfast BT7 1NN, UK,

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References 127