HR 7578
Encyclopedia
HR 7578 is a BY Draconis variable
binary star
located in the night sky
at RA
19h 54m 17s and Dec
-23º 56′ 28″ in the constellation
of Sagittarius
. The stars have a total Proper Motion
of 0.426 "/yr
.
At a distance
of 46.4 light Years (13.61 ± 1.70 pc
) and an absolute magnitude
of 5.46 these star
s have a combined apparent magnitude
of 6.23 when viewed from earth
.
The two stars, aged between 5x108 and 2x109 years old, appear to be remarkably similar. Both seem to be K3 V or K4V class
star
s. Both stars appear to have a mass
of not less than 0.85±0.03 Solar mass
es, and an abundance of heavier elements
.
They seem, on current evidence, to rotate in 16.35 ± 1 days.
The star system is also known as HD
188088, HIP- Hip 97944, cd-24° 15668 A, Gl 770 A, YPC: 4686.00 and V4200 Sgr.
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...
binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
located in the night sky
Night sky
The term night sky refers to the sky as seen at night. The term is usually associated with astronomy, with reference to views of celestial bodies such as stars, the Moon, and planets that become visible on a clear night after the Sun has set. Natural light sources in a night sky include moonlight,...
at RA
Right ascension
Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:...
19h 54m 17s and Dec
Declination
In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...
-23º 56′ 28″ 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....
of Sagittarius
Sagittarius (constellation)
Sagittarius is a constellation of the zodiac, the one containing the galactic center. Its name is Latin for the archer, and its symbol is , a stylized arrow. Sagittarius is commonly represented as a centaur drawing a bow...
. The stars have a total Proper Motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...
of 0.426 "/yr
Year
A year is the orbital period of the Earth moving around the Sun. For an observer on Earth, this corresponds to the period it takes the Sun to complete one course throughout the zodiac along the ecliptic....
.
At a distance
Distance measures (cosmology)
Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe. They are often used to tie some observable quantity to another quantity that is not directly...
of 46.4 light Years (13.61 ± 1.70 pc
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
) and an absolute magnitude
Absolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
of 5.46 these 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...
s have a combined 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 6.23 when viewed 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 two stars, aged between 5x108 and 2x109 years old, appear to be remarkably similar. Both seem to be K3 V or K4V class
Star class
Star class could refer to:* Star-class sailboats raced in the Summer Olympic Games since 1932* GWR star-class locomotives from the 19th century.* GWR 4000 class locomotives from the early 20th century.* Stellar classification...
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...
s. Both stars appear to have a mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
of not less than 0.85±0.03 Solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es, and an abundance of heavier elements
Metallicity
In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
.
They seem, on current evidence, to rotate in 16.35 ± 1 days.
The star system is also known as HD
Henry Draper Catalogue
The Henry Draper Catalogue is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension , published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the...
188088, HIP- Hip 97944, cd-24° 15668 A, Gl 770 A, YPC: 4686.00 and V4200 Sgr.