Delta Eridani, which is
Latinized from δ Eridani, is a
star in the
equatorial Equatorial may refer to something related to:
*Earth's equator
**the tropics, the Earth's equatorial region
**tropical climate
*the Celestial equator
** equatorial orbit
**equatorial coordinate system
** equatorial mount, of telescopes
* equatorial ...
constellation of
Eridanus.
The star is visible to the naked eye and has been observed to vary in slightly brightness between magnitudes 3.51 and 3.56,
although subsequent observations did not bear this out.
It is relatively near to 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 ...
, with a distance of about 29.5
light years as determined from
parallax.
The star is drifting closer with a
radial velocity of −6 km/s.
Delta Eridani is sometimes called Rana:
[ '']Rana
Rana may refer to:
Astronomy
* Rana (crater), a crater on Mars
* Delta Eridani or Rana, a star
People, groups and titles
* Rana (name), a given name and surname (including a list of people and characters with the name)
* Rana (title), a histori ...
'' means "the frog
A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' is ...
" in Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, but derivation of this name is uncertain. The name was approved by the International Astronomic Union on 4 April 2022.
Structure
The stellar classification of this star is K0 IV,[ matching a ]subgiant
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...
star that has exhausted its core hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
. This has caused the star to expand and become cooler than a comparable main sequence star. Stellar modelling indicates it is near the end of the subgiant stage and about to transition into a giant
In folklore, giants (from Ancient Greek: ''gigas'', cognate giga-) are beings of human-like appearance, but are at times prodigious in size and strength or bear an otherwise notable appearance. The word ''giant'' is first attested in 1297 fr ...
. It is an estimated six[ billion years old with 33% more mass than the Sun. The star has 2.3 times the girth of the Sun and is radiating three times the Sun's luminosity from its photosphere at an effective temperature of 4,986 K.][
Delta Eridani is catalogued as a suspected ]RS Canum Venaticorum variable An RS Canum Venaticorum variable is a type of variable star. The variable type consists of close binary stars having active chromospheres which can cause large stellar spots. These spots are believed to cause variations in their observed luminosi ...
in 1983,[ but the ]activity level
Activity may refer to:
* Action (philosophy), in general
* Human activity: human behavior, in sociology behavior may refer to all basic human actions, economics may study human economic activities and along with cybernetics and psychology may stu ...
for the star is so low that this is considered doubtful. This class of variables occurs in close binary systems. A low projected rotational velocity
Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface.
The rotation of a star produces an equatorial bulg ...
of under 1 km/s and the lack of radial velocity variation suggests that this putative variable is being viewed from nearly pole-on. However, an examination of the star using interferometry does not detect the presence of a companion at the expected distance.[
]
Chinese name
In Chinese
Chinese can refer to:
* Something related to China
* Chinese people, people of Chinese nationality, citizenship, and/or ethnicity
**''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation
** List of ethnic groups in China, people of ...
, (), meaning '' Celestial Meadows'', refers to an asterism consisting of δ Eridani, γ Eridani, π Eridani, ε Eridani, ζ Eridani, η Eridani, π Ceti, τ1 Eridani, τ2 Eridani, τ3 Eridani, τ4 Eridani, τ5 Eridani, τ6 Eridani, τ7 Eridani, τ8 Eridani and τ9 Eridani.[ Consequently, the ]Chinese name
Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are ofte ...
for δ Eridani itself is (, en, the Third Star of Celestial Meadows.)[
]
See also
* List of star systems within 25–30 light-years
References
External links
*
*
nStars entry
{{DEFAULTSORT:Delta Eridani
K-type subgiants
Eridani, Delta
Suspected variables
Eridanus (constellation)
Eridani, Delta
BD-10 0728
Eridani, 23
0150
023249
017378
1136
Rana
Rana may refer to:
Astronomy
* Rana (crater), a crater on Mars
* Delta Eridani or Rana, a star
People, groups and titles
* Rana (name), a given name and surname (including a list of people and characters with the name)
* Rana (title), a histori ...