15 Andromedae, abbreviated 15 And, is a single,
[ ]variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...
[ in the northern ]constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The first constellati ...
of Andromeda. ''15 Andromedae'' is the Flamsteed designation, while its variable star designation is V340 And.[ Its apparent visual magnitude is 5.55,][ which indicates it is faintly visible to the naked eye. Its estimated distance from the Earth is 252 light years, and it is moving further away with a heliocentric radial velocity of 13 km/s.][
Rufener and Bartholdi (1982) included the star (under the name HD 221756) in their list of 333 variable, microvariable and suspected variable stars, based on multicolor ]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 electr ...
performed at several observatories in the 1960s and 1970s. However they were unable to conclusively demonstrate that the star's brightness varied.stellar classification
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 gratin ...
of A1 III,[ an A-type main-sequence star with a class of A1 Va,][ or a Lambda Boötis star with a class of kA1hA3mA0.5 Va+.][ It is a Delta Scuti variable that changes in brightness by 0.03 magnitude.][ Two variability cycles, with periods 0.0403 and 0.0449 days, have been observed, a common feature for Lambda Boötis stars.][ The star is around 130][ million years old and has a high rotation rate, showing 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 bu ...
of 105 km/s.[ It has 2.7 times the mass of the Sun and is radiating 27 times the Sun's luminosity from its ]photosphere
The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will esc ...
at an effective temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...
of 9,225 K.[
This system has an excess emission of infrared radiation that suggests the presence of an orbiting disk of dust at a distance of around 50 AU from the host star.][
]
References
External links
Image 15 Andromedae
{{DEFAULTSORT:15 Andromedae
A-type giants
A-type main-sequence stars
Delta Scuti variables
Lambda Boötis stars
Andromeda (constellation)
Durchmusterung objects
Andromedae, 15
221756
116354
8947
Andromedae, V340