7 Vulpeculae is a

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 ...

system approximately 940

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away in the northern constellation of

Vulpecula Vulpecula is a faint constellation in the northern sky. Its name is Latin for "little fox", although it is commonly known simply as the fox. It was identified in the seventeenth century, and is located in the middle of the Summer Triangle (an ...

. It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.34. The system is moving closer to the Earth with a heliocentric

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection ...

of −38 km/s. This is a single-lined spectroscopic binary star system with an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of 69.3 days and an eccentricity of 0.16. The visible component is a Be star with a

stellar classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...

of B4–5 III–IVe that appears to be nearing the end of its

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 ...

lifetime. It shows a rapid rotation rate with a

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulge ...

of 300 km/s, which is just below the estimated critical velocity of 367 km/s. There is a small variability in the magnitude of this star that occurs over 0.559 days this is likely the rotation period of the primary star. The nature of the companion is unknown, but based upon its mass it may be a K- or M-type star. However, it could be a

white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...

that has previously undergone a mass transfer event with the now visible component. Because of the lack of

X-ray emission Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays. Several types of astrophysical objects emit X-rays. They include galaxy clusters, black holes in active galactic nuclei (AGN), ...

from the system, a third possibility is that the companion is a naked He star that has been stripped of its hydrogen envelope.

References

External links

* {{DEFAULTSORT:Vulpeculae, 07 B-type main-sequence stars Spectroscopic binaries Vulpecula Flamsteed objects Durchmusterung objects 183537 095818 7409