27 Canis Majoris
Encyclopedia
27 Canis Majoris, also called 27 CMa, is a star system
in the constellation
Canis Major
. It is approximately 1580 light years from Earth
and has a mean apparent magnitude
of +4.42.
The primary component, 27 Canis Majoris A, is a blue-white B-type
giant
with an apparent magnitude
of +4.9. It is also a spectroscopic binary with an orbital period
of 0.262 days.
The second component, 27 Canis Majoris B, is separated from the primary by 0.1 arcseconds and has an orbital period of 31 years. Its apparent magnitude is +5.4 and it is classified as a Gamma Cassiopeiae type variable star
. Due to its variable nature, the brightness of the system varies from magnitude +4.42 to +4.82.
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....
Canis Major
Canis Major
Canis Major is one of the 88 modern constellations, and was included in the 2nd-century astronomer Ptolemy's 48 constellations. Its name is Latin for 'greater dog', and is commonly represented as one of the dogs following Orion the hunter...
. It is approximately 1580 light years 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...
and has 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 +4.42.
The primary component, 27 Canis Majoris A, is a blue-white B-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 +4.9. It is also a spectroscopic binary with an orbital period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
of 0.262 days.
The second component, 27 Canis Majoris B, is separated from the primary by 0.1 arcseconds and has an orbital period of 31 years. Its apparent magnitude is +5.4 and it is classified as a Gamma Cassiopeiae type 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...
. Due to its variable nature, the brightness of the system varies from magnitude +4.42 to +4.82.