The Carnegie Supernova Project II

Observations of the luminous red nova AT 2014ej^⋆,⋆⋆

¹ Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
e-mail: max@phys.au.dk
² School of Physics, O’Brien Centre for Science North, University College Dublin, Belfield, Dublin 4, Ireland
³ Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Høegh-Guldbergs Gade 6B, 8000 Aarhus C, Denmark
⁴ Las Campanas Observatory, Carnegie Observatories, Casilla, 601 La Serena, Chile
⁵ Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Spain
⁶ Departamento de Física Teórica y del Cosmos, Universidad de Granada, 18071 Granada, Spain
⁷ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁸ Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago, Chile
⁹ Millennium Institute of Astrophysics, Santiago, Chile
¹⁰ The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm, Sweden
¹¹ The George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 877843, USA
¹² Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA
¹³ Department of Physics, Florida State University, Tallahassee, FL 32306, USA
¹⁴ Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks, Rm 100, Norman, OK 73019-2061, USA
¹⁵ Observatories of the Carnegie Institution for Science, 813 Santa Barbara St, Pasadena, CA 91101, USA
¹⁶ National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁷ School of Physics and Astronomy, Faculty of Science, Monash University, Clayton, VIC 3800, Australia
¹⁸ Runaway Bay, Gold Coast, Queensland, Australia
¹⁹ School of Physics & Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA, UK
²⁰ Leyburn Observatory, Queensland 4129, Australia
²¹ Parkdales Observatory, Oxford, New Zealand
²² University of North Carolina at Chapel Hill, Campus Box 3255, Chapel Hill, NC 27599-3255, USA
²³ SOAR Telescope, La Serena 1700000, Chile
²⁴ Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UK

Received: 25 March 2020
Accepted: 15 May 2020

Abstract

We present optical and near-infrared broadband photometry and optical spectra of AT 2014ej from the Carnegie Supernova Project-II. These observations are complemented with data from the CHilean Automatic Supernova sEarch, the Public ESO Spectroscopic Survey of Transient Objects, and from the Backyard Observatory Supernova Search. Observational signatures of AT 2014ej reveal that it is similar to other members of the gap-transient subclass known as luminous red novae (LRNe), including the ubiquitous double-hump light curve and spectral properties similar to that of LRN SN 2017jfs. A medium-dispersion visual-wavelength spectrum of AT 2014ej taken with the Magellan Clay telescope exhibits a P Cygni Hα feature characterized by a blue velocity at zero intensity of ≈110 km s⁻¹ and a P Cygni minimum velocity of ≈70 km s⁻¹. We attribute this to emission from a circumstellar wind. Inspection of pre-outbust Hubble Space Telescope images yields no conclusive progenitor detection. In comparison with a sample of LRNe from the literature, AT 2014ej lies at the brighter end of the luminosity distribution. Comparison of the ultra-violet, optical, infrared light curves of well-observed LRNe to common-envelope evolution models from the literature indicates that the models underpredict the luminosity of the comparison sample at all phases and also produce inconsistent timescales of the secondary peak. Future efforts to model LRNe should expand upon the current parameter space we explore here and therefore may consider more massive systems and a wider range of dynamical timescales.