V841 Ophiuchi (Nova Ophiuchi 1848) was 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 ...

discovered by

John Russell Hind John Russell Hind FRS FRSE LLD (12 May 1823 – 23 December 1895) was an English astronomer. Life and work John Russell Hind was born in 1823 in Nottingham, the son of lace manufacturer John Hind and Elizabeth Russell, and was educated at ...

on 27 April 1848. It was the first object of its type discovered since 1670. At the time of its discovery, it had an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of 5.6, but may have reached magnitude 2 at its peak, making it easily visible to the naked eye. Near peak brightness it was described as "bright red" or "scalet", probably due to Hα line emission. Its brightness is currently varying slowly around magnitude 13.5. The area of the sky surrounding this nova had been examined frequently by astronomers prior to the nova's discovery, because it was near the reported location of "52 Serpentis", a star

John Flamsteed John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, ''Catalogus Britannicus'', and a star atlas called ''Atlas Coe ...

had included in his catalogue with erroneous coordinates. Like all

cataclysmic variable 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 ...

(CV) stars, novae are short-period binary stars with a "donor" star transferring material to a white dwarf. In the case of V841 Ophiuchi, the orbital period is 14.43 hours, which is unusually long for a CV; the vast majority of such systems have periods below 10 hours. Peters and Thorstensen derive an orbital inclination of 30°±10 with respect to our line of sight which, combined with the relatively large separation implied by the orbital period, would explain why V841 Ophiuchi is not an

eclipsing binary 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 w ...

. They also found that the donor star is somewhat cooler than the Sun, with a

spectral type In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...

of K3±2. Modern observations during a 30-year time interval show that V841 Ophiuchi undergoes regular brightness variations with a period of 3.4 years, and an amplitude of about 0.3 magnitudes, which may be due to oscillations in the donor star similar to our Sun's

solar cycle The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfa ...

. Nonperiodic "flickering" brightness variations have been reported, on timescales as short as 100 seconds.

References

{{DEFAULTSORT:V841 Ophiuchi Novae Hercules (constellation) 1848 in science Ophiuchi, V841