SN 2019np
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SN 2019np was a Type Ia supernova[1] event in NGC 3254, which is an unbarred spiral galaxy in the northern Constellation of Leo Minor. Based on the Tully–Fisher relation, this galaxy is located at a distance of 107.0 ± 22.2 million light-years (32.80 ± 6.8 Mpc) from the Milky Way.[3] This supernova was discovered January 9, 2019 by Kōichi Itagaki,[2] and reached maximum two weeks later.[4] It was the brightest supernova observed in the year 2019.[5]
| Event type | Supernova |
|---|---|
| Type Ia[1] | |
| Constellation | Leo Minor |
| Right ascension | 10h 29m 21.980s[2] |
| Declination | +29° 30′ 38.30″[2] |
| Epoch | J2000 |
| Distance | 107.0 ± 22.2 Mly (32.80 ± 6.8 Mpc)[3] |
| Redshift | 0.00452[2] |
| Host | NGC 3254[2] |
| Colour (B-V) | −0.06±0.03[3] |
| Peak apparent magnitude | 13.62±0.15[3] |
Observations
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]