Transitional events in the spectrophotometric regime between stripped envelope and superluminous supernovae Pretince, Simon Galbany González, Lluis Delgado Mancheño, M. Muñoz Torres, S. Supernovae General KM, MRM, and SJP are supported by H2020 ERC grant no. 758638. LG acknowledges financial support from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 839090, and from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2019 Ramon y Cajal programme RYC2019-027683. TMB ´ was funded by the CONICYT PFCHA / DOCTORADOBECAS CHILE/2017-72180113. MG is supported by the EU Horizon 2020 research and innovation programme under grant agreement no. 101004719. SGG acknowledges support by FCT under Project CRISP PTDC/FIS-AST-31546/2017. MN is supported by a Royal Astronomical Society Research Fellowship and H2020 ERC grant no. 948381. T-WC acknowledges the EU Funding under Marie Skłodowska-Curie grant H2020-MSCA-IF-2018-842471. The LT is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, as part of ePESSTO+ (the advanced Public ESO Spectroscopic Survey for Transient Objects Survey). ePESSTO+ observations were obtained under ESO programme ID 1103.D-0328 (PI: Inserra). The WHT is operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof´ısica de Canarias. SJP thanks GPL for many insightful discussions at the bar over the last few years. The division between stripped-envelope supernovae (SE-SNe) and superluminous supernovae (SLSNe) is not well-defined in either photometric or spectroscopic space. While a sharp luminosity threshold has been suggested, there remains an increasing number of transitional objects that reach this threshold without the spectroscopic signatures common to SLSNe. In this work, we present data and analysis on four SNe transitional between SE-SNe and SLSNe; the He-poor SNe 2019dwa and 2019cri, and the He-rich SNe 2019hge and 2019unb. Each object displays long-lived and variable photometric evolution with luminosities around the SLSN threshold of Mr < -19.8 mag. Spectroscopically however, these objects are similar to SE-SNe, with line velocities lower than either SE-SNe and SLSNe, and thus represent an interesting case of rare transitional events. 2021-12-09T12:42:39Z 2021-12-09T12:42:39Z 2021-10-05 journal article S J Prentice, C Inserra, S Schulze, M Nicholl, P A Mazzali, S D Vergani, L Galbany, J P Anderson, C Ashall, T W Chen, M Deckers, M Delgado Mancheño, R González Díaz, S González-Gaitán, M Gromadzki, C P Gutiérrez, L Harvey, A Kozyreva, M R Magee, K Maguire, T E Müller-Bravo, S Muñoz Torres, P J Pessi, J Sollerman, J Teffs, J H Terwel, D R Young, Transitional events in the spectrophotometric regime between stripped envelope and superluminous supernovae, Monthly Notices of the Royal Astronomical Society, Volume 508, Issue 3, December 2021, Pages 4342–4358, [https://doi.org/10.1093/mnras/stab2864] http://hdl.handle.net/10481/71950 10.1093/mnras/stab2864 eng info:eu-repo/grantAgreement/EC/H2020/758638 info:eu-repo/grantAgreement/EC/H2020/839090 info:eu-repo/grantAgreement/EC/H2020/101004719 info:eu-repo/grantAgreement/EC/H2020/948381 info:eu-repo/grantAgreement/EC/H2020/MSCA-IF-2018-842471 http://creativecommons.org/licenses/by-nc-nd/3.0/es/ open access Atribución-NoComercial-SinDerivadas 3.0 España Oxford University Press