The Sub-mm Variability of IRC+10216 and $o$ Ceti. (arXiv:1908.04555v1 [astro-ph.SR])

The Sub-mm Variability of IRC+10216 and $o$ Ceti. (arXiv:1908.04555v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Dharmawardena_T/0/1/0/all/0/1">Thavisha E. Dharmawardena</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kemper_F/0/1/0/all/0/1">Francisca Kemper</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wouterloot_J/0/1/0/all/0/1">Jan G. A. Wouterloot</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Scicluna_P/0/1/0/all/0/1">Peter Scicluna</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marshall_J/0/1/0/all/0/1">Jonathan P. Marshall</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wallstrom_S/0/1/0/all/0/1">Sofia H. J. Wallstrom</a>

We present the sub-mm variability of two of the most well studied AGB stars,
IRC+10216 and $o$ Ceti. The data are obtained at $450~micron$ and
$850~micron$ as part of pointing calibration observations for the James Clerk
Maxwell Telescope’s SCUBA-2 instrument over a span of 7 years. The periods are
derived using non-parametric methods, texttt{Gatspy Supersmoother} and
texttt{P4J} in order not to assume an underlying shape to the periodicity.
These were compared to two Lomb-Scargle parametric methods. We find that for
both sources and wavelengths the periods derived from all methods are
consistent within $1sigma$. The $850~micron$ phase folded light curves of
IRC+10216 show a time lag of $sim 540$ days compared to its optical
counterpart. We explore the origins of the sub-mm variability and the phase lag
using radiative transfer models. Combining the modelling with findings in the
literature, we find that the sub-mm emission and phase lag can be partially
attributed to the dust formation/destruction cycle. A second, unknown mechanism
must be invoked; we defer an investigation of the origin and nature of this
mechanism to a future work.

We present the sub-mm variability of two of the most well studied AGB stars,
IRC+10216 and $o$ Ceti. The data are obtained at $450~micron$ and
$850~micron$ as part of pointing calibration observations for the James Clerk
Maxwell Telescope’s SCUBA-2 instrument over a span of 7 years. The periods are
derived using non-parametric methods, texttt{Gatspy Supersmoother} and
texttt{P4J} in order not to assume an underlying shape to the periodicity.
These were compared to two Lomb-Scargle parametric methods. We find that for
both sources and wavelengths the periods derived from all methods are
consistent within $1sigma$. The $850~micron$ phase folded light curves of
IRC+10216 show a time lag of $sim 540$ days compared to its optical
counterpart. We explore the origins of the sub-mm variability and the phase lag
using radiative transfer models. Combining the modelling with findings in the
literature, we find that the sub-mm emission and phase lag can be partially
attributed to the dust formation/destruction cycle. A second, unknown mechanism
must be invoked; we defer an investigation of the origin and nature of this
mechanism to a future work.

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