V392 Persei
Nova in the constellation Perseus
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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.
 | |
| 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 | |
| AAVSO 0435+47, V392 Per, 2MASS J04432138+4721257, Gaia DR2 254361745823908736[7] | |
| Database references | |
| SIMBAD | data |
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]
Nova eruption
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]
System
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]
Gallery
Dwarf nova V392 Persei over the ESO Supernova Planetarium & Visitor Centre.[13]
V392 Persei, 2 May 2018, 22:00 UT. The slightly fainter nearby star is 9th magnitude BD+47°1026. Up is approximately east.
