A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
A study in scarlet. II. Spectroscopic properties of a sample of intermediate-luminosity red transients
Alaotsikko: II. Spectroscopic properties of a sample of intermediate-luminosity red transients
Tekijät: Valerin, G.; Pastorello, A.; Mason, E.; Reguitti, A.; Benetti, S.; Cai, Y.-Z.; Chen, T.-W.; Eappachen, D.; Elias-Rosa, N.; Fraser, M.; Gangopadhyay, A.; Hsiao, E.; Howell, D.; Inserra, C.; Izzo, L.; Jencson, J.; Kankare, E.; Kotak, R.; Lundqvist, P.; Mazzali, P.; Misra, K.; Pignata, G.; Prentice, S.; Sand, D.; Smartt, S.; Stritzinger, M.; Tartaglia, L.; Valenti, S.; Anderson, J.; Andrews, J.; Amaro, R.; Barbarino, C.; Brennan, S.; Bufano, F.; Callis, E.; Cappellaro, E.; Dastidar, R.; Della, Valle; Fiore, A.; Fulton, M.; Galbany, L.; Gromadzki, M.; Heikkilä, T.; Hiramatsu, D.; Karamehmetoglu, E.; Kuncarayakti, H.; Leloudas, G.; Limongi, M.; Lundquist, M.; McCully, C.; Müller-Bravo, T.; Nicholl, M.; Ochner, P.; Padilla, Gonzalez; Paraskeva, E.; Pellegrino, C.; Rau, A.; Reichart, D.; Reynolds, T.; Roy, R.; Salmaso, I.; Shahbandeh, M.; Singh, M.; Sollerman, J.; Turatto, M.; Tomasella, L.; Wyatt, S.; Young, D.
Kustantaja: EDP Sciences
Julkaisuvuosi: 2025
Journal: Astronomy and Astrophysics
Tietokannassa oleva lehden nimi: Astronomy & Astrophysics
Artikkelin numero: A43
Vuosikerta: 695
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202451735
Verkko-osoite: https://doi.org/10.1051/0004-6361/202451735
Rinnakkaistallenteen osoite: https://research.utu.fi/converis/portal/detail/Publication/492083951
Aims. We investigate the spectroscopic characteristics 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 unveiling the physical origin of these events based on the analysis of the collected datasets.
Methods. We present the extensive optical and near-infrared (NIR) spectroscopic monitoring of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd and AT 2019udc. First we focus on the evolution of the most prominent spectral features observed in the low-resolution spectra. We then present a more detailed description of the high-resolution spectrum collected for NGC 300 2008OT-1 with the Very Large Telescope equipped with UVES. Finally, we describe our analysis of late-time spectra of NGC 300 2008OT-1 and AT 2019ahd through comparisons with both synthetic and observed spectra.
Results. Balmer and Ca lines dominate the optical spectra, revealing the presence of slowly moving circumstellar medium (CSM) around the objects. The line luminosity of Hα, Hβ, and Ca ii NIR triplet presents a double peaked evolution with time, possibly indicative of interaction between fast ejecta and the slow CSM. The high-resolution spectrum of NGC 300 2008OT-1 reveals a complex circumstellar environment, with the transient being surrounded by a slow (∼30 km s−1) progenitor wind. At late epochs, optical spectra of NGC 300 2008OT-1 and AT 2019ahd show broad (∼2500 km s−1) emission features at ∼6170 Å and ∼7000 Å which are unprecedented for ILRTs. We find that these lines originate most likely from the blending of several narrow lines, possibly of iron-peak elements.
Key words. circumstellar matter – supernovae: general – supernovae: individual: NGC 300 2008OT-1 – supernovae: individual: AT 2019abn –supernovae: individual: AT 2019ahd – supernovae: individual: AT 2019udc
Ladattava julkaisu This is an electronic reprint of the original article. |  |
Julkaisussa olevat rahoitustiedot:
G.V., A.P., A.R., S.B., L.T., N.E.R. and I.S. acknowledge financial support from PRIN-INAF 2022 “Shedding light on the nature of gap transients: from the observations to the models”. A.R. also acknowledges financial support from the GRAWITA Large Program Grant (PI P. D’Avanzo). Y.-Z. Cai is supported by the National Natural Science Foundation of China (NSFC, Grant No. 12303054), the Yunnan Fundamental Research Projects A43, page 15 of 27 Valerin, G., et al.: A&A, 695, A43 (2025) (Grant No. 202401AU070063) and the International Centre of Supernovae, Yunnan Key Laboratory (No. 202302AN360001). L.G. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033, and the European Social Fund (ESF). This work was funded by ANID, Millennium Science Initiative, ICN12_009 M.N. is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948381). Part of the funding for GROND (both hardware as well as personnel) was generously granted from the Leibniz-Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). H.K. was funded by the Academy of Finland projects 324504 and 328898. R.K. acknowledges support from the Research Council of Finland (340613). We thank the staff of the various observatories where data were obtained for their assistance. Based on observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. Observations from the Nordic Optical Telescope were obtained through the NUTS2 collaboration which are supported in part by the Instrument Centre for Danish Astrophysics (IDA) and the Finnish Centre for Astronomy with ESO (FINCA) via Academy of Finland grant nr 306531. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA). Time-domain research by the University of Arizona team, and D.J.S. is supported by NSF grants AST-1821987, 1813466, 1908972, 2108032, and 2308181, and by the Heising-Simons Foundation under grant #2020-1864. H.K. was funded by the Research Council of Finland projects 324504, 328898, and 353019. This work makes use of data from the Las Cumbres Observatory network. The LCO team is supported by NSF grants AST–1911225 and AST–1911151, and NASA SWIFT grant 80NSSC19K1639. Data were also obtained at the Liverpool Telescope, which is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos with financial support from the UK Science and Technology Facilities Council. Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. 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 program IDs 1103.D-0328 and 106.216C (PI: Inserra). LCO data have been obtained via OPTICON. The OPTICON project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant no. 730890. Time domain research by the University of Arizona team and D.J.S. is supported by NSF grants AST-1821987, 1813466, 1908972, & 2108032, and by the Heising-Simons Foundation under grant #20201864.
