LMC S154: the first Magellanic symbiotic recurrent nova. (arXiv:1902.02621v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ilkiewicz_K/0/1/0/all/0/1">Krystian Ilkiewicz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mikolajewska_J/0/1/0/all/0/1">Joanna Mikolajewska</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miszalski_B/0/1/0/all/0/1">Brent Miszalski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gromadzki_M/0/1/0/all/0/1">Mariusz Gromadzki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Monard_B/0/1/0/all/0/1">Berto Monard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Amigo_P/0/1/0/all/0/1">Pia Amigo</a>
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.
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.
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