V906 Carinae
V906 Carinae, also known as Nova Carinae 2018, was a nova in the Milky Way galaxy which appeared in the constellation Carina, near the 5th magnitude star HD 92063. It was discovered on images taken on 20.32 March 2018 by the All Sky Automated Survey for SuperNovae, and to magnitude 6.62 later the same day.
Also on 21 March 2018, long exposure spectrographic measurements of ASASSN-18fv, specifically in the 3800Å to 7300Å range, were captured using CCD imaging. Detailed analysis of the spectral data confirmed that ASASSN-18fv exhibited characteristics of a classical nova.
All novae are binary stars, with a "donor" star orbiting a white dwarf. The two stars are so close to each other that material is transferred from the donor to the white dwarf. In the case of V906 Carinae, data from the Transiting Exoplanet Survey Satellite suggests that the binary system has an orbital period of either 1.641 hours or twice that value. The mass of the white dwarf has been estimated to be, and the donor is believed to be a dwarf of spectral type K or M and a mass of.
One of the stars monitored by the Bright-star Target Explorer nanosatellite constellation was HD 92063. V906 Carinae was close enough to that star to be serendipitously observed by BRITE. In the BRITE data, the nova's maximum brightness occurred on 14 April 2018. BRITE provided a measurement of the nova's brightness every 1.6 hours, allowing the fluctuations near the peak of the outburst to be seen clearly. There were eight post-maximum flares with amplitudes of a few tenths of a magnitude each of which lasted 1 to 3 days. These flares in the visible portion of the EM spectrum occurred at the same times that γ-ray flares were seen by Fermi-LAT. Because the γ-ray flares are believed to arise from shocks in the ejected material, their correlation with visible flares suggests that most of the visible light from the nova may be produced in shocks, rather than the nuclear burning on the white dwarf's surface.