Multi-wavelength Photometry and Progenitor Analysis of the Nova V906 Car

With my former Yale-NUS student Jerrick Wee and former collaborator from Caltech Nadeja Blagorodnova, we studied an erupting nova known as V906 Car in optical and infrared wavelengths, using remotely operated telescopes in Chile. Two of our Soka University of America students, Taiga Morioka and Jeff Facey, contributed to the work. The paper was published in the Astrophysical Journal in 2020.

The paper was entitled “Multi-wavelength Photometry and Progenitor Analysis of the Nova V906 Car,” and presented an extensive observational study of the classical nova V906 Car (also known as Nova Car 2018 and ASASSN-18fv), discovered by the ASAS-SN survey on March 16, 2018. We provided detailed optical and infrared photometry data, highlighting the nova’s evolution over 126 days. The nova’s light curve showed a steep decline with a decline rate parameter ∆m15(B) = 0.88 and negligible host galaxy reddening. High-resolution spectroscopy estimated the extinction towards the nova as AV = 1.11+0.54−0.39. The progenitor system analysis suggests a white dwarf mass of < 0.8M☉, and a donor star likely being a K-M dwarf with 0.23-0.43M☉. The study contributes valuable data on novae’s light curves and spectral energy distribution, enhancing our understanding of their physical properties and progenitor systems.

The figure displays the light curves of V906 Car across various optical (BVRI) and near-infrared (JHK) bands. The nova exhibited a characteristic rise to maximum brightness followed by a rapid decline, consistent with a C-class nova. The presence of a secondary maximum in the near-infrared bands, particularly in the H and K filters, indicates complex interactions and the possible formation of dust within the ejecta. These detailed light curves help in understanding the photometric evolution and underlying physical mechanisms driving the brightness changes in classical novae.

The study of V906 Car provides critical insights into the broader astrophysical understanding of nova systems. By capturing the nova’s early rise and detailed multi-wavelength photometry, the paper contributes to refining models of nova outbursts, particularly the shock-powered mechanisms suggested by correlated optical and γ-ray emissions. The accurate measurements of extinction and distance further validate the use of classical novae as standard candles for cosmic distance calculations. Additionally, the analysis of the progenitor system enriches our knowledge of white dwarf accretion processes and the role of donor stars in nova systems, which are essential for understanding stellar evolution and binary interactions.

(note: this overview is provided with assistance from ChatGPT 4o).