Nu
2 Coronae Borealis is a solitary,
[ orange-hued star located in the northern constellation of ]Corona Borealis
Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a se ...
. It is faintly visible to the naked eye, having an apparent visual magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...
of +5.4.[ Based upon an annual parallax shift of 5.49 mas,][ it is located roughly 590 light years from the ]Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
. At that distance, the visual magnitude is diminished by an extinction
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
of 0.1 due to interstellar dust
Cosmic dust, also called extraterrestrial dust, star dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 micrometers). Larger particles are c ...
.[
This is an ]evolved
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
red giant star with a stellar classification of K5 III.[ The measured ]angular diameter
The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is ...
of Nu2 Coronae Borealis is .[ At its estimated distance, this yields a physical size of about 50 times the ]radius of the Sun
Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3:
:1\,R_ = 6.957\t ...
.[ Nu2 Coronae Borealis is radiating 530][ times the ]Sun's luminosity
The solar luminosity (), is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun.
One nominal ...
from its photosphere at an effective temperature of 3,940 K.[
]
References
{{DEFAULTSORT:Nu2 Coronae Borealis
K-type giants
Corona Borealis
Corona Borealis, Mu
Durchmusterung objects
Coronae Borealis, 21
147767
080214
6108