The spectral evolution of AT 2018dyb and the presence of metal lines in tidal disruption events

Understand

We present light curves and spectra of the tidal disruption event (TDE) ASASSN-18pg / AT 2018dyb spanning a period of one year.

• The event shows a plethora of strong emission lines, including the Balmer series, He II, He I and metal lines of O III $\lambda$3760 and N III $\lambda\lambda$ 4100, 4640 (blended with He II).
• The latter lines are consistent with originating from the Bowen fluorescence mechanism.
• By analyzing literature spectra of past events, we conclude that these lines are common in TDEs.