Intermediate Luminosity Red Transient
Intermediate Luminosity Red Transients (ILRT), is a subclass of stellar transients that occupy the luminosity gap between classical nova and typical supernovae.[1][2]
ILRTs are part of the broader category of Intermediate Luminosity Optical Transient or gap transients, which include diverse phenomena such as luminous red nova and supernova impostors. However, ILRTs are distinguished by their spectroscopic features and light curve shapes, often resembling faint Type II supernovae.[3][4]
Progenitors
Progenitors are dust-enshrouded, detected primarily in MIR but faint or undetected in optical pre-explosion images. Estimated masses are 8–12 M⊙, consistent with super-asymptotic giant branch (super-AGB) stars.[5][6]
Late-time observations show some ILRTs fading below progenitor luminosity in MIR, supporting terminal explosions.[7]
The favored explanation is electron capture supernova in a super-AGB stars with degenerate O-Ne-Mg cores. Electron capture on Ne and Mg reduces pressure support, triggering collapse.[1][8]
Alternatives include non-terminal outbursts or mergers, but fading below progenitor levels and low yields favor terminal electron capture supernova.[9]
Table
| Transient | Galaxy | Reported | Date | Observatory | Notes and Reference |
|---|---|---|---|---|---|
| SN 2008S | NGC 6946 | 1 February 2008 | Prototype[5] | ||
| NGC 300-OT | NGC 300 | 14 May 2008 | [6] | ||
| AT 2019abn | M51 | 22 January 2019 | ATLAS |
References
- ^ a b Hiramatsu, Daichi; Howell, D. Andrew; Van Dyk, Schuyler D.; Goldberg, Jared A.; Maeda, Keiichi; Moriya, Takashi J.; Tominaga, Nozomu; Nomoto, Ken’ichi; Hosseinzadeh, Griffin; Arcavi, Iair; McCully, Curtis; Burke, Jamison; Bostroem, K. Azalee; Valenti, Stefano; Dong, Yize (September 2021). "The electron-capture origin of supernova 2018zd". Nature Astronomy. 5 (9): 903–910. arXiv:2011.02176. Bibcode:2021NatAs...5..903H. doi:10.1038/s41550-021-01384-2. ISSN 2397-3366.
- ^ Berger, E.; Soderberg, A. M.; Chevalier, R. A.; Fransson, C.; Foley, R. J.; Leonard, D. C.; Debes, J. H.; Diamond-Stanic, A. M.; Dupree, A. K.; Ivans, I. I.; Simmerer, J.; Thompson, I. B.; Tremonti, C. A. (2009-07-10). "An Intermediate Luminosity Transient in NGC 300: The Eruption of a Dust-Enshrouded Massive Star". The Astrophysical Journal. 699 (2): 1850–1865. arXiv:0901.0710. Bibcode:2009ApJ...699.1850B. doi:10.1088/0004-637X/699/2/1850. ISSN 0004-637X.
- ^ Moran, S.; Kotak, R.; Fraser, M.; Pastorello, A.; Cai, Y.-Z.; Valerin, G.; Mattila, S.; Cappellaro, E.; Kravtsov, T.; Gutiérrez, C. P.; Elias-Rosa, N.; Reguitti, A.; Lundqvist, P.; Filippenko, A. V.; Brink, T. G. (2024-08-01). "Red eminence: The intermediate-luminosity red transient AT 2022fnm". Astronomy & Astrophysics. 688: A161. arXiv:2406.02816. Bibcode:2024A&A...688A.161M. doi:10.1051/0004-6361/202348225. ISSN 0004-6361.
- ^ "Intermediate-Luminosity Red Transients". STScI. Retrieved 2025-11-14.
- ^ a b Prieto, José L.; Kistler, Matthew D.; Thompson, Todd A.; Yüksel, Hasan; Kochanek, Christopher S.; Stanek, Krzysztof Z.; Beacom, John F.; Martini, Paul; Pasquali, Anna; Bechtold, Jill (2008-07-01). "Discovery of the Dust-Enshrouded Progenitor of SN 2008S with Spitzer". The Astrophysical Journal. 681 (1): L9–L12. arXiv:0803.0324. Bibcode:2008ApJ...681L...9P. doi:10.1086/589922. ISSN 0004-637X.
- ^ a b Bond, Howard E.; Bedin, Luigi R.; Bonanos, Alceste Z.; Humphreys, Roberta M.; Monard, L. A. G. Berto; Prieto, José L.; Walter, Frederick M. (2009-04-20). "The 2008 Luminous Optical Transient in the Nearby Galaxy NGC 300". The Astrophysical Journal. 695 (2): L154–L158. arXiv:0901.0198. Bibcode:2009ApJ...695L.154B. doi:10.1088/0004-637X/695/2/L154. ISSN 0004-637X.
- ^ Adams, S. M.; Kochanek, C. S.; Prieto, J. L.; Dai, X.; Shappee, B. J.; Stanek, K. Z. (August 2016). "Almost gone: SN 2008S and NGC 300 2008OT-1 are fainter than their progenitors". Monthly Notices of the Royal Astronomical Society. 460 (2): 1645–1657. arXiv:1511.07393. Bibcode:2016MNRAS.460.1645A. doi:10.1093/mnras/stw1059. ISSN 0035-8711.
- ^ Miyaji, Shigeki; Nomoto, Ken'ichi; Yokoi, Kõichi; Sugimoto, Daiichiro (August 1980). "Supernova Triggered by Electron Captures". Publications of the Astronomical Society of Japan. 32 (2): 303–329. Bibcode:1980PASJ...32..303M. doi:10.1093/pasj/32.2.303. ISSN 0004-6264.
- ^ Rose, Sam; Lau, Ryan M.; Jencson, Jacob E.; Kasliwal, Mansi M.; De, Kishalay; Ressler, Michael E.; Fox, Ori D.; Hankins, Matthew J. (February 2025). "Investigating the Electron-capture Supernova Candidate AT 2019abn with JWST Spectroscopy". The Astrophysical Journal. 980 (1): L14. Bibcode:2025ApJ...980L..14R. doi:10.3847/2041-8213/adad61. ISSN 0004-637X.