| Abstract : | Classical symbiotic outbursts (Z-And type) are the most common type of outburst in symbiotic systems. However, our understanding of them is sparse. In the literature, four different models are proposed to explain such outbursts; such as 1) Expansion of WD photosphere at a near constant bolometric luminosity due to an increased accretion rate that exceeds study burning, 2) Shell flash or thermal pulse similar to nova outburst, 3) Dwarf nova-like outburst due to accretion disk instability, 4) Combination nova, where an outburst is initiated by disk instability following an enhanced shell burning. On 2020 Feb 28, one of the early known but poorly studied symbiotic stars, CM Aql, reported undergoing an outburst by Gaia alert (Gaia20bcf). We present optical spectroscopic follow-up observations of CM Aql from the Himalayan Chandra Telescope (HCT) for the past two and half years, studying the spectral evolution during the Z-And type outburst. In this study, we present the evolution of different parameters, such as the temperature and luminosity of the hot component in the system, and compare it with previously reported studies. We also present the pre-outburst light curve showing wave-like variation originating from orbital motion and post-outburst light curves showing multiple peaks, which are typical for Z-And outbursts. |
