Theta Tauri
Encyclopedia
Theta Tauri is a star system
in the constellation
Taurus
and a member of the Hyades
open cluster
. It is approximately 155 light years
from Earth
. The system is dominated by two 3rd magnitude stars, θ¹ Tauri and θ² Tauri, which are separated by 5.62 arcminutes (0.094°) on the sky. θ¹ Tauri is the dimmer component, an orange K-type
giant
with an apparent magnitude
of +3.84. θ² Tauri is a white A-type
giant
with a mean apparent magnitude
of +3.40. θ² Tauri is classified as a Delta Scuti type
variable star
and its brightness varies from magnitude +3.35 to +3.42 with a period of 1.82 hours.
Both bright stars are spectroscopic binaries and have at least one closer companion. θ¹ Tauri has a 7th magnitude companion 0.082 arcseconds, or at least 4 astronomical unit
s (AU), away from the primary. θ² has a 6th magnitude companion 0.005 arcseconds, or at least 2 AU, distant. It completes an orbit once every 141 days.
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Taurus
Taurus (constellation)
Taurus is one of the constellations of the zodiac. Its name is a Latin word meaning 'bull', and its astrological symbol is a stylized bull's head:...
and a member of the Hyades
Hyades (star cluster)
The Hyades is the nearest open cluster to the Solar System and one of the best-studied of all star clusters. The Hipparcos satellite, the Hubble Space Telescope, and infrared color-magnitude diagram fitting have been used to establish a distance to the cluster's center of ~153 ly...
open cluster
Open cluster
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way Galaxy, and many more are thought to exist...
. It is approximately 155 light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
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...
. The system is dominated by two 3rd magnitude stars, θ¹ Tauri and θ² Tauri, which are separated by 5.62 arcminutes (0.094°) on the sky. θ¹ Tauri is the dimmer component, an orange K-type
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...
giant
Giant star
A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...
with an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of +3.84. θ² Tauri is a white A-type
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...
giant
Giant star
A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...
with a mean apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of +3.40. θ² Tauri is classified as a Delta Scuti type
Delta Scuti variable
A Delta Scuti variable is a variable star which exhibits variations in its luminosity due to both radial and non-radial pulsations of the star's surface. Typical brightness fluctuations are from 0.003 to 0.9 magnitudes in V over a period of a few hours, although the amplitude and period of the...
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...
and its brightness varies from magnitude +3.35 to +3.42 with a period of 1.82 hours.
Both bright stars are spectroscopic binaries and have at least one closer companion. θ¹ Tauri has a 7th magnitude companion 0.082 arcseconds, or at least 4 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s (AU), away from the primary. θ² has a 6th magnitude companion 0.005 arcseconds, or at least 2 AU, distant. It completes an orbit once every 141 days.