LMC S154: the first Magellanic symbiotic recurrent nova

Abstract

Classical nova outburst has been suggested for a number of extragalactic symbiotic stars, but in none of the systems has it been proven. In this work we study the nature of one of these systems, LMC S154. We gathered archival photometric observations in order to determine the timescales and nature of variability in this system. Additionally we carried out photometric and spectroscopic monitoring of the system and fitted synthetic spectra to the observations. Carbon abundance in the photosphere of the red giant is significantly higher than that derived for the nebula, which confirms pollution of the circumbinary material by the ejecta from nova outburst. The photometric and spectroscopic data show that the system reached quiescence in 2009, which means that for the first time all of the phases of a nova outburst were observed in an extragalactic symbiotic star. The data indicate that most probably there were three outbursts observed in LMC S154, which would make this system a member of a rare class of symbiotic recurrent novae. The recurrent nature of the system is supported by the discovery of coronal lines in the spectra, which are observed only in symbiotic stars with massive white dwarfs and with short-recurrence-time outbursts. Gathered evidence is sufficient to classify LMC S154 as the first bona fide extragalactic symbiotic nova, which is likely a recurrent nova. It is also the first nova with a carbon-rich donor.

Chandra High Energy Transmission Gratings Spectra of V3890 Sgr

“…They are called "recurrent" because they have been observed in outburst more than once, although all novae are thought to have repeated outbursts on different, secular timescales (e.g., Prialnik 1986). Only a small number of RNe are known, 10 in the Galaxy (see the review by Orio 2015), 3 in the Large Magellanic Cloud (Bode et al 2016;Mróz et al 2016) with a recent additional candidate (Iłkiewicz et al 2019), and 12 in M31 with 4 additional candidates (Shafter et al 2015). Of the 10 known Galactic RNe, 4 are "symbiotic novae," relatively rare novae in long orbital period systems with a red giant companion.…”

The first results of DORIS RINEX data processing at the INASAN Analysis Center

“…Примером симбиотической повторной новой является LMCS 154, вспыхнувшая в 1940 и 1977 г. [48]. Интересно, что симбиотические явления, то есть проявление аккреции астрономическими объектами вещества звездного ветра, известны и среди галактических объектов.…”

Symbiotic Star T CrB as an Extreme SU UMa–type Dwarf Nova

“…The mass donor of the system is a red giant, classifying the system as a symbiotic star (see Kenyon 1986, and references therein). This makes T CrB a member of a rare group of symbiotic recurrent novae, which has only six members known thus far (RS Oph, T CrB, V3890 Sgr, V745 Sco, LMC S154, and V618 Sgr; see Iłkiewicz et al 2019;Merc et al 2023, and references therein).…”