V392 Persei, also known as Nova Persei 2018, is a bright

nova A nova (plural novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramati ...

in the constellation

Perseus In Greek mythology, Perseus (Help:IPA/English, /ˈpɜːrsiəs, -sjuːs/; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of Mycenae and of the Perseid dynasty. He was, alongside Cadmus ...

discovered on April 29, 2018. It was previously known as a dwarf nova.

Dwarf nova

A ''U Geminorum-type variable star'' or ''dwarf nova'' is a type of

cataclysmic variable star In astronomy, cataclysmic variable stars (CVs) are stars which irregularly increase in brightness by a large factor, then drop back down to a quiescent state. They were initially called novae (), since ones with an outburst brightness visible to ...

consisting of a close

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

system in which one of the components is a white dwarf that accretes matter from a cool

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

or subgiant companion. 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. Its spectrum in the quiescent state has been studied and only the cool star is detected. The spectrum shows emission lines of

hydrogen-alpha H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm in air and 656.46 nm in vacuum; it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha ...

(Hα) and both neutral and ionised helium. The brightest recorded observations is at magnitude 5.6.

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. Observations with Fermi-LAT on April 30 show a strong gamma-ray source at the coordinates of the nova.

Photometry Photometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electrom ...

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.

System

V392 Persei is the southern of a pair of stars separated by 8.5". The symbiotic pair are unresolved, with an orbital period of only 3.21997 days, and the nature of the cool component is unclear. The

spectral energy distribution A spectral energy distribution (SED) is a plot of energy versus frequency or wavelength of light (not to be confused with a 'spectrum' of flux density vs frequency or wavelength). It is used in many branches of astronomy to characterize astron ...

is inconsistent with a bright giant star but it could be less luminous red clump giant or subgiant. If the cool component was a

red dwarf as expected for a dwarf nova, then the system would need to be closer than the suggested by its

Gaia In Greek mythology, Gaia (; from Ancient Greek , a poetical form of , 'land' or 'earth'),, , . also spelled Gaea , is the personification of the Earth and one of the Greek primordial deities. Gaia is the ancestral mother—sometimes parthenog ...

parallax.

Gallery

File:Nova over Supernova.jpg, Dwarf nova V392 Persei over the

ESO Supernova Planetarium & Visitor Centre The ESO Supernova Planetarium & Visitor Centre is an astronomy centre located at the site of the European Southern Observatory (ESO) Headquarters in Garching bei München. It offers exhibitions, guided tours and planetarium shows that feature o ...

. File:Nova Persei2018.jpg, V392 Persei, 2 May 2018, 22:00 UT. The slightly fainter nearby star is 9th magnitude BD+47°1026. Up is approximately east.

References

External links