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ASASSN-18tb: a most unusual Type Ia supernova observed by TESS and SALT

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cris.lastimport.scopus2024-02-12T19:36:02Z
dc.abstract.enWe present photometric and spectroscopic observations of the unusual Type Ia supernova ASASSN-18tb, including a series of Southern African Large Telescope spectra obtained over the course of nearly six months and the first observations of a supernova by the Transiting Exoplanet Survey Satellite. We confirm a previous observation by Kollmeier et al. showing that ASASSN-18tb is the first relatively normal Type Ia supernova to exhibit clear broad (˜1000 km s<SUP>-1</SUP>) H α emission in its nebular-phase spectra. We find that this event is best explained as a sub-Chandrasekhar mass explosion producing M_{ Ni} ≈ 0.3 {M}_⊙. Despite the strong H α signature at late times, we find that the early rise of the supernova shows no evidence for deviations from a single-component power-law and is best fit with a moderately shallow power law of index 1.69 ± 0.04. We find that the H α luminosity remains approximately constant after its initial detection at phase +37 d, and that the H α velocity evolution does not trace that of the Fe III λ4660 emission. These suggest that the H α emission arises from a circumstellar medium (CSM) rather than swept-up material from a non-degenerate companion. However, ASASSN-18tb is strikingly different from other known CSM-interacting Type Ia supernovae in a number of significant ways. Those objects typically show an H α luminosity two orders of magnitude higher than what is seen in ASASSN-18tb, pushing them away from the empirical light-curve relations that define `normal' Type Ia supernovae. Conversely, ASASSN-18tb exhibits a fairly typical light curve and luminosity for an underluminous or transitional SN Ia, with M<SUB>R</SUB> ≈ -18.1 mag. Moreover, ASASSN-18tb is the only SN Ia showing H α from CSM interaction to be discovered in an early-type galaxy.
dc.affiliationUniwersytet Warszawski
dc.contributor.authorVallely, P. J.
dc.contributor.authorFausnaugh, M.
dc.contributor.authorJha, S. W.
dc.contributor.authorTucker, M. A.
dc.contributor.authorEweis, Y.
dc.contributor.authorShappee, B. J.
dc.contributor.authorKochanek, C. S.
dc.contributor.authorStanek, K. Z.
dc.contributor.authorChen, Ping
dc.contributor.authorDong, Subo
dc.contributor.authorPrieto, J. L.
dc.contributor.authorSukhbold, T.
dc.contributor.authorThompson, Todd A.
dc.contributor.authorBrimacombe, J.
dc.contributor.authorStritzinger, M. D.
dc.contributor.authorHoloien, T. W. -S.
dc.contributor.authorBuckley, D. A. H.
dc.contributor.authorGromadzki, Mariusz
dc.contributor.authorBose, Subhash
dc.date.accessioned2024-01-24T16:56:42Z
dc.date.available2024-01-24T16:56:42Z
dc.date.copyright2019-03-20
dc.date.issued2019
dc.description.accesstimeBEFORE_PUBLICATION
dc.description.financeNie dotyczy
dc.description.number2
dc.description.versionORIGINAL_AUTHOR
dc.description.volume487
dc.identifier.doi10.1093/MNRAS/STZ1445
dc.identifier.issn0035-8711
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/101176
dc.identifier.weblinkhttp://adsabs.harvard.edu/abs/2019MNRAS.487.2372V
dc.languageeng
dc.pbn.affiliationastronomy
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.relation.pages2372-2384
dc.rightsOther
dc.sciencecloudnosend
dc.titleASASSN-18tb: a most unusual Type Ia supernova observed by TESS and SALT
dc.typeJournalArticle
dspace.entity.typePublication