HD 166
Encyclopedia
HD 166 or V439 Andromedae (ADS 69 A) is a 6th magnitude star in the constellation Andromeda
, approximately 45 light years away from Earth
. It is a variable star
of the BY Draconis
type, with a variation in brightness smaller than 0.2 magnitude. It is an orange star of the spectral type K0V, meaning it has a surface temperature of 3,500 to 5,000 kelvin and is a dwarf star
like our Sun
, yet cooler and dimmer. It is within one degree of the star Alpha Andromedae
.
It is located at celestial (X,Y,Z) coordinates of 39.1, 1.13, 21.7 galactic (X,Y,Z) coordinates in ly: -14.1, 34.9, -24.1 and is found at right ascension and declination 0h6m36.75s, +29°1'17.6".
The star has a proper motion of 0.422 arcsec/yr (114.1° from north). It has a spectral
class of K0e, is luminosity class V and has an estimated visual luminosity of 59% of Sol
. It has a diameter that is about 1.06 x Sol and has a radial velocity of -5.5 km/s.
It is estimated to be about 200 million years old based on its chromospheric activity.
The habitable zone
for an Earth
-like
planet
would be about 0.77 A.U.s from the star
.
Andromeda (constellation)
Andromeda is a constellation in the northern sky. It is named after Andromeda, the princess in the Greek legend of Perseus who was chained to a rock to be eaten by the sea monster Cetus...
, approximately 45 light years away from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. It is a variable star
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
of the BY Draconis
BY Draconis variable
BY Draconis variables are main sequence variable stars of late spectral types, usually K or M. The name comes from the archetype for this category of variable star system, BY Draconis. They exhibit variations in their luminosity due to rotation of the star coupled with star spots, and other...
type, with a variation in brightness smaller than 0.2 magnitude. It is an orange star of the spectral type K0V, meaning it has a surface temperature of 3,500 to 5,000 kelvin and is a dwarf star
Dwarf star
The term dwarf star refers to a variety of distinct classes of stars.* Dwarf star alone generally refers to any main sequence star, a star of luminosity class V.** Red dwarfs are low-mass main sequence stars....
like our Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
, yet cooler and dimmer. It is within one degree of the star Alpha Andromedae
Alpha Andromedae
Alpha Andromedae , which has the traditional names Alpheratz and Sirrah , is the brightest star in the constellation of Andromeda. Located immediately northeast of the constellation of Pegasus, it is the northeastern star of the Great Square of Pegasus...
.
It is located at celestial (X,Y,Z) coordinates of 39.1, 1.13, 21.7 galactic (X,Y,Z) coordinates in ly: -14.1, 34.9, -24.1 and is found at right ascension and declination 0h6m36.75s, +29°1'17.6".
The star has a proper motion of 0.422 arcsec/yr (114.1° from north). It has a spectral
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
class of K0e, is luminosity class V and has an estimated visual luminosity of 59% of Sol
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. It has a diameter that is about 1.06 x Sol and has a radial velocity of -5.5 km/s.
It is estimated to be about 200 million years old based on its chromospheric activity.
The habitable zone
Habitable zone
In astronomy and astrobiology, a habitable zone is an umbrella term for regions that are considered favourable to life. The concept is inferred from the empirical study of conditions favourable for Life on Earth...
for an Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
-like
Terrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun...
planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
would be about 0.77 A.U.s from the star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
.