NSVS 14256825, also known as V1828 Aquilae, is 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 ...

system (of the Algol type) in the constellation of Aquila. The system comprises a subdwarf OB star and red dwarf star. The two stars orbit each other every 2.648976 hours. Based on the stellar parallax of the system, observed by '' Gaia'', the system is located approximately 2,700 light-years (840 parsecs) away.

Nomenclature

The system is most commonly referred to using its designation from the Northern Sky Variability Survey (NSVS), a survey of stars with

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 ...

s between 8 and 15.5. It also has a

variable star designation In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the conste ...

, V1828 Aquilae.

Eclipse timing variations

NSVS 14256825 has been extremely well-studied using

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 electro ...

, but the resulting models often contradict each other, even with similar statistical significance, or with data that are collected later. Many studies have found that this system exhibits eclipse timing variations (ETVs) that are significant, cyclic and not explainable by other stellar mechanisms such as the

Applegate mechanism The Applegate mechanism (Applegate's mechanism or Applegate effect) explains long term orbital period variations seen in certain eclipsing binaries. As a main sequence star goes through an activity cycle, the outer layers of the star are subject t ...

. In 2012, it was found that the orbit of NSVS 14256825 was increasing at a rate of days per orbit. Initially, in 2012 it was claimed that two giant planets were in orbit around the binary, with masses of 2.9 and 8.1 times the mass of

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

orbiting with periods of 3.5 and 6.9 years respectively. Another paper claimed the existence of one planet with a mass 12 times that of Jupiter, in a 20-year orbit. However, subsequent studies have come up with different results with masses up to and periods down to 8.83 years. Studies also do not agree on whether one substellar body can explain the ETVs, or whether additional companions are necessary, but further research is needed to obtain better coverage of data.

References

{{DEFAULTSORT:NSVS 14256825 Algol variables Eclipsing binaries Aquila (constellation) Aquilae, V1828 O-type subdwarfs M-type main-sequence stars J20200045+0437564

Nomenclature

Eclipse timing variations

See also

References