Delta1 Gruis, Latinized from δ1 Gruis, is a candidate
binary star
A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...
system in the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
Grus. With a peak apparent visual magnitude of 4.0 it is bright enough to be seen with the naked eye at night. The distance to this system, as determined using an annual
parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...
shift of 10.54
mas
Mas, Más or MAS may refer to:
Film and TV
* Más y Menos, fictional superhero characters, from the Teen Titans animated television series
* Más (Breaking Bad), "Más" (''Breaking Bad''), a season three episode of ''Breaking Bad''
Songs
* Más ( ...
as seen from the Earth, is around 309
light year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s. It is gradually moving away from the Sun with a
radial velocity
The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...
of +4.9 km/s.
The brighter component of this system is an evolved, yellow-hued, G-typegiant star with a
stellar classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...
of G6/8 III. It is a semiregular variable that ranges between apparent magnitudes 3.99 and 4.2, located 325 light-years from Earth. Delta1 Gruis has around 3 times the mass and 24 times the diameter of the Sun. The fainter companion is a magnitude 12.8 star at an
angular separation
Angular distance \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer.
Angular distance appears in mathematics (in pa ...