The Carnegie Supernova Project II. Observations of the luminous red nova AT 2014ej

We present optical and near-infrared broadband photometry and optical spectra of AT 2014ej from the Carnegie Supernova ProjectII. 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 doublehump 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.
USA's NSF AST-0306969 AST-0607438 AST-1008343 AST-1613426 AST-1613455 AST-1613472
Danish Agency for Science and Technology and Innovation
Independent Research Fund Denmark (IRFD) 8021-00170B
VILLUM FONDEN 13261
Science Foundation Ireland
European Union (EU) 754513
Aarhus University Research Foundation
European Union (EU) 839090
European Union (EU) PGC2018095317-B-C21
Ministry of Economy, Development, and Tourism's Millennium Science Initiative IC120009
National Science Foundation (NSF) AST-1613455
Texas A&M University Mitchell/Heep/Munnerlyn Chair in Observational Astronomy
Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 1191038
ESO Telescopes at the La Silla Paranal Observatory 191.D-0935 096.B-0230