R Aquarii
Encyclopedia
R Aquarii is a variable star
in the constellation
Aquarius
.
R Aquarii is a symbiotic star believed to contain a white dwarf and a Mira-type variable
in a binary star
system. The orbital period
is approximately 44 years. The main Mira-type star is a red giant
, and varies in brightness by a factor of several hundred and with a period of slightly more than a year; this variability was discovered by Karl Ludwig Harding
in 1810. It has a distance of about 200 parsec
, and is one of the nearest symbiotic stars and a well known jet source.
By its gravitation
al pull, the white dwarf draws in material from the red giant and occasionally ejects some of the surplus in weird loops to form the nebula seen in the linked image. The whole system appears reddened because it is situated in a very dusty region of space, and its blue light is absorbed before reaching us.
The nebula around R Aquarii is also known as Cederblad 211. According to Tom Polakis, as of 1998 no one had succeeded to observe this challenging object visually. It is possible that the nebula is the remnant of a nova-like outburst, which may have been observed by Japanese astronomers, in the year 930
AD.
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...
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....
Aquarius
Aquarius (constellation)
Aquarius is a constellation of the zodiac, situated between Capricornus and Pisces. Its name is Latin for "water-bearer" or "cup-bearer", and its symbol is , a representation of water....
.
R Aquarii is a symbiotic star believed to contain a white dwarf and a Mira-type variable
Mira
Mira also known as Omicron Ceti , is a red giant star estimated 200-400 light years away in the constellation Cetus. Mira is a binary star, consisting of the red giant Mira A along with Mira B. Mira A is also an oscillating variable star and was the first non-supernova variable star discovered,...
in a 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...
system. The 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...
is approximately 44 years. The main Mira-type star is a red giant
Red giant
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower...
, and varies in brightness by a factor of several hundred and with a period of slightly more than a year; this variability was discovered by Karl Ludwig Harding
Karl Ludwig Harding
Karl Ludwig Harding was a German astronomer notable for having discovered the asteroid 3 Juno.-Biography:...
in 1810. It has a distance of about 200 parsec
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 is one of the nearest symbiotic stars and a well known jet source.
By its gravitation
Gravitation
Gravitation, or gravity, is a natural phenomenon by which physical bodies attract with a force proportional to their mass. Gravitation is most familiar as the agent that gives weight to objects with mass and causes them to fall to the ground when dropped...
al pull, the white dwarf draws in material from the red giant and occasionally ejects some of the surplus in weird loops to form the nebula seen in the linked image. The whole system appears reddened because it is situated in a very dusty region of space, and its blue light is absorbed before reaching us.
The nebula around R Aquarii is also known as Cederblad 211. According to Tom Polakis, as of 1998 no one had succeeded to observe this challenging object visually. It is possible that the nebula is the remnant of a nova-like outburst, which may have been observed by Japanese astronomers, in the year 930
930
Year 930 was a common year starting on Friday of the Julian calendar.- Europe :* With the establishment of the Althing, now one of the world's oldest parliaments, the Icelandic Commonwealth is founded....
AD.