Speakers
Description
We study the evolution of V339 Del (Nova Del 2013) during 0.37-75 days after discovery. Spectra from the Liverpool Telescope were collected and analysed to find the velocity of ejecta (v$_{ej}$), relative radiation with respect to continuum level (R$^*$$_{\lambda}$), and FWHM of the radiation. The evolution of light curve was explained by adopting an ideal nova light curve as criteria. We found that the evolution of V339 Del during t = 0.37 – 75 days can be explained in 7 phases: 1) Initial rise (t = 0 - 0.6 days); nova is suddenly brighter from V ~ 11 to ~6.4. A maximum v$_{ej}$ is ~ 2400 km/s. R$^*$$_{\lambda}$ and FWHM first increases and then decreases where this joint (t = 0.35 days) turns out to be the first detection of X-ray. 2) Pre-maximum halt (0.6–1.2 days); There is a halt of brightness around V ~ 5.1–5.9, decreasing v$_{ej}$, increasing R$^*$$_{\lambda}$ with decreasing FWHM. 3) Final rise (t = 1.2–1.5 days); Nova is brighter again to maximum. The variation of v$_{ej}$ and radiation have similar trend to the halt phase. 4) Maximum (t = 1.5–2.5 days); Nova has maximum brightness of V = 4.45 ± 0.01 (t = 1.67 days) decreasing v$_{ej}$ and increasing R$^*$$_{\lambda}$ until maximum value and the decreasing afterward, while FWHM decreases from the final rise. 5) Early decline (t = 2.5 – 35 days); Nova has a drop in brightness and v$_{ej}$. The last measurement of v$_{ej}$ is ~ 1100–1200 km/s at t = 35.5 days. The radiation seems to have 2 distinct phases in this early decline including: First stage (t = 2.2~12 days) where R$^*$$_{\lambda}$ and FWHM increase and nebular spectra begins around t ~ 10 days. In this stage the nova shell expands optical depth reduces, marking pseudo-photosphere shrink. Second stage (t = 12~35 days) where R$^*$$_{\lambda}$ and FWHM decrease and SED shift to near-IR until not visible in optical (t = 28 days). Iron curtain (t ~ +25 days) was found near the time of first soft X-ray detection (t = 35.6 days). 6) Transition (t = 35–60 days); Brightness decreases where R$^*$$_{\lambda}$ and FWHM gradually increase meaning it reveals deeper pseudo-photosphere. 7) Final decline (t = 60~75 days); Nova is fainter than 6 magnitude from maximum, R$^*$$_{\lambda}$ and FWHM decrease, Nova is now in nebular phase permanently allowing us to see the surface of white dwarf for the first time.
