SN 2019np

This supernova was discovered by Japanese amateur astronomer Kōichi Itagaki on January 9, 2019, using a 0.35-m telescope.^[2] The early spectrum was consistent with a Type Ia supernova.^[1][6] On January 11, it was measured at an apparent visual magnitude of 16.68 with an estimated two weeks until maximum.^[4] It reached visual magnitude 13.6 at maximum.^[3]

The spectral evolution of SN 2019np followed the normal pattern for a Type Ia supernova. The velocity of the ejecta was around 10,200 km/s at maximum, as measured from ionized silicon. Early observations showed an infrared excess, which may be explained by a collision between the ejecta and a companion star. The data is best explained by a solar mass companion on the main sequence.^[3]

The explosion data is most consistent with a carbon-oxygen white dwarf that evolved from a star with five times the mass of the Sun. This compact object accreted matter from its companion until its mass approached the Chandrasekhar limit, when it detonated.^[7] The explosion generated an estimated 0.66±0.05 M_☉ of synthesized nickel.^[3]

• Perez-Torres, M.; et al. (January 2019), "Radio constraints on the mass-loss rate of the Type Ia SN 2019np", The Astronomer's Telegram, 12411, Bibcode:2019ATel12411....1P.
• Konyves-Toth, R.; et al. (January 2019), "BVRI Photometry of the Young Type Ia SN 2019np", The Astronomer's Telegram, 12378, Bibcode:2019ATel12378....1K.