Optical observations of the fast nova V1674 Herculis

TL;DR

This study details the optical spectral and lightcurve evolution of the fast nova V1674 Herculis over 150 days, revealing its bipolar morphology, orbital period, and ongoing nebular activity, indicating a complex post-eruption behavior.

Contribution

It provides detailed optical spectral analysis, orbital period measurement, and morphological insights of V1674 Herculis, highlighting the presence of bipolar structure and persistent nebular lines.

Findings

Orbital period of 0.153 days determined

Bipolar morphology with polar blobs and equatorial ring identified

Persistent nebular lines indicating ongoing activity

Abstract

We present the evolution of optical spectra and lightcurves of the fast nova V1674 Herculis during 150 days past its eruption. Using the post-eruption AAVSO light curve, we have calculated the orbital period of V1674 Her to be 0.153 days. There is no unambiguous white dwarf spin period in our data. The optical spectra show that the ionisation increases with time. A morpho-kinematic analysis of the H$\alpha$ line profile indicates a bipolar morphology with polar blobs and an equatorial ring. Lyman beta fluorescence is found to be the dominant mechanism for the excitation of neutral oxygen. On day 19.87, [Ne III] & [Ne V] lines are present, indicating the presence of the ONe white dwarf. On day 147.66, the nebular lines are still present, implying that the nova had not gone into quiescence yet; this spectrum is accretion-dominated.