A multiwavelength light curve analysis of the classical nova KT Eri: Optical contribution from a large irradiated accretion disk

TL;DR

This study models the optical and X-ray light curves of KT Eri, revealing a large irradiated accretion disk's role during outburst and estimating key system parameters, concluding KT Eri is likely not a recurrent nova.

Contribution

The paper presents a detailed light curve analysis of KT Eri, incorporating a large irradiated disk model, and derives system parameters, providing new insights into its classification and outburst behavior.

Findings

White dwarf mass estimated at 1.3 solar masses

Distance to KT Eri determined as 4.2 kpc

KT Eri is likely not a recurrent nova

Abstract

KT Eri is a classical nova which went into outburst in 2009. Recent photometric analysis in quiescence indicates a relatively longer orbital period of 2.6 days, so that KT Eri could host a very bright accretion disk during the outburst like in the recurrent nova U Sco, the orbital period of which is 1.23 days. We reproduced the optical $V$ light curve as well as the supersoft X-ray light curve of KT Eri in outburst, assuming a large irradiated disk during a nova wind phase of the outburst while a normal size disk after the nova winds stop. This result is consistent with the temporal variation of wide-band $V$ brightness that varies almost with the intermediate-band Str\"omgren $y$ brightness, because the $V$ flux is dominated by continuum radiation, the origin of which is a photospheric emission from the very bright disk. We obtained the white dwarf mass to be $M_{\rm WD}= 1.3\pm0.02 ~M_\odot$, the hydrogen-burning turnoff epoch to be $\sim 240$ days after the outburst, the distance modulus in the $V$ band to be $(m-M)_V=13.4\pm 0.2$, and the distance to KT Eri to be $d=4.2\pm0.4$ kpc for the reddening of $E(B-V)= 0.08$. The peak absolute $V$ brightness is about $M_{V, \rm max}= -8.0$ and the corresponding recurrence time is $\sim 3,000$ yr from its ignition mass together with the mean mass-accretion rate of $\dot{M}_{\rm acc}\sim 1\times 10^{-9} ~M_\odot$ yr$^{-1}$ in quiescence. Thus, we suggest that KT Eri is not a recurrent nova.