Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Perseus |
Right ascension | 04h 43m 21.37s [1] |
Declination | +47° 21′ 25.9″ [1] |
Apparent magnitude (V) | 6.3 - 16.9 [2] |
Characteristics | |
B−V color index | +1.0 [3] |
V−R color index | +0.9 [3] |
Variable type | dwarf nova & nova [1] |
Astrometry | |
Proper motion (μ) |
RA: 0.193
[4]
mas/
yr Dec.: −1.749 [4] mas/ yr |
Parallax (π) | 0.2573 ± 0.0516 mas [4] |
Distance | 4161+2345 −440 [5] pc |
Absolute magnitude (MV) | −10.1 (max) [6] |
Other designations | |
Database references | |
SIMBAD | data |
V392 Persei, also known as Nova Persei 2018, is a bright nova in the constellation Perseus discovered on April 29, 2018. It was previously known as a dwarf nova.
A U Geminorum-type variable star or dwarf nova is a type of cataclysmic variable star consisting of a close binary star system in which one of the components is a white dwarf that accretes matter from a cool main sequence or subgiant companion. [8] V392 Persei was discovered in 1970 and received its variable star designation a year later. It is normally visual magnitude 17.4 and experiences outbursts of 2-3 magnitudes. [1] Its spectrum in the quiescent state has been studied and only the cool star is detected. The spectrum shows emission lines of hydrogen-alpha (Hα) and both neutral and ionised helium. [3] The brightest recorded observations is at magnitude 5.6. [6]
On April 29, 2018 it was discovered by Yuji Nakamura to be extremely bright, and it was spectroscopically confirmed as a nova outburst with magnitude 6.2 on April 30. The spectrum includes broad Hα and FeII emission lines with P Cygni profiles. The absorption core is blueshifted by a velocity of 2,680 km/s, which would be the expansion velocity from the nova explosion. [9]
Observations with Fermi-LAT on April 30 show a strong gamma-ray source at the coordinates of the nova. [10] Photometry of the nova from Konkoly Observatory on May 1, 2018 give apparent magnitudes of 7.38 in the V band and 8.22 in the B band, suggesting it is already declining. [11]
V392 Persei is the southern of a pair of stars separated by 8.5". [2]
The symbiotic pair are unresolved, with an orbital period of only 3.21997 days, [12] and the nature of the cool component is unclear. The spectral energy distribution is inconsistent with a bright giant star but it could be less luminous red clump giant or subgiant. If the cool component was a main sequence red dwarf as expected for a dwarf nova, then the system would need to be closer than the 13,000 ly suggested by its Gaia parallax. [6]