Theta Boötis
Encyclopedia
Theta Boötis is a star
in the constellation
Boötes
. It has the traditional name Asellus Primus (Latin for "first donkey
colt") and the Flamsteed designation
23 Boötis.
This star, along with the other Asselus (ι Boo
and κ Boo
) and λ Boo
, were Al Aulād al Dhiʼbah (ألعولد ألذعب - al aulād al dhiʼb), "the Whelps of the Hyenas". .
In Chinese
, , meaning Celestial Spear
, refers to an asterism consisting of θ Boötis, κ2 Boötis
and ι Boötis
. Consequently, θ Boötis itself is known as
+4.04 and belongs to the spectral class
F7V. It is approximately 47 light years from Earth
. From about 4300 BC
until 3942 BC
, it was the closest star to the celestial north pole
visible to the naked eye, although it was still too far away and too dim to be regarded as a pole star
.
There is a nearby 11th magnitude optical companion star about 70 arcseconds away. This is a class M2.5 dwarf that is separated by approximately 1,000 AUs
. It is uncertain whether they are gravitationally bound, but they do have a common motion through space and so the two stars probably share a common origin.
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...
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....
Boötes
Boötes
Boötes is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from the Greek Βοώτης, Boōtēs, meaning herdsman or plowman...
. It has the traditional name Asellus Primus (Latin for "first donkey
Donkey
The donkey or ass, Equus africanus asinus, is a domesticated member of the Equidae or horse family. The wild ancestor of the donkey is the African Wild Ass, E...
colt") and the Flamsteed designation
Flamsteed designation
Flamsteed designations for stars are similar to Bayer designations, except that they use numbers instead of Greek letters. Each star is assigned a number and the Latin genitive of the constellation it lies in...
23 Boötis.
This star, along with the other Asselus (ι Boo
Iota Boötis
Iota Boötis is a star system in the constellation Boötes. It has the traditional name Asellus Secundus and the Flamsteed designation 21 Boötis....
and κ Boo
Kappa Boötis
Kappa Boötis is a star system in the constellation Boötes. It has the traditional name Asellus Tertius and the Flamsteed designation 17 Boötis...
) and λ Boo
Lambda Boötis
Lambda Boötis is a star in the constellation Boötes.Lambda Boötis is a white A-type main sequence dwarf with an apparent magnitude of +4.18. It is approximately 97.1 light-years from Earth. Lambda Boötis is the prototype of a group of rare stars known as Lambda Boötis stars, all of which are...
, were Al Aulād al Dhiʼbah (ألعولد ألذعب - al aulād al dhiʼb), "the Whelps of the Hyenas". .
In Chinese
Chinese language
The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...
, , meaning Celestial Spear
Purple Forbidden enclosure
The Purple Forbidden enclosure is one of the San Yuan or Three enclosures. Stars and constellations of this group lie near the north celestial pole and visible all year from temperate latitudes in the Northern Hemisphere.-Asterisms:The asterisms are :...
, refers to an asterism consisting of θ Boötis, κ2 Boötis
Kappa Boötis
Kappa Boötis is a star system in the constellation Boötes. It has the traditional name Asellus Tertius and the Flamsteed designation 17 Boötis...
and ι Boötis
Iota Boötis
Iota Boötis is a star system in the constellation Boötes. It has the traditional name Asellus Secundus and the Flamsteed designation 21 Boötis....
. Consequently, θ Boötis itself is known as
Properties
Theta Boötis has apparent magnitudeApparent 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...
+4.04 and belongs to the spectral class
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
F7V. It is approximately 47 light years 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...
. From about 4300 BC
5th millennium BC
The 5th millennium BC saw the spread of agriculture from the Near East throughout southern and central Europe.Urban cultures in Mesopotamia and Anatolia flourished, developing the wheel. Copper ornaments became more common, marking the Chalcolithic. Animal husbandry spread throughout Eurasia,...
until 3942 BC
40th century BC
-Events:*c. 4000 BC, Liangzhu culture in China.*c. 4000 BC, More than 100 dwellings surrounding a community center, a cemetery and a kiln are built in Jiangzhai, near modern Xi'an, China.*Start of Naqada culture in Egypt....
, it was the closest star to the celestial north pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...
visible to the naked eye, although it was still too far away and too dim to be regarded as a pole star
Pole star
The term "Pole Star" usually refers to Polaris, which is the current northern pole star, also known as the North Star.In general, however, a pole star is a visible star, especially a prominent one, that is approximately aligned with the Earth's axis of rotation; that is, a star whose apparent...
.
There is a nearby 11th magnitude optical companion star about 70 arcseconds away. This is a class M2.5 dwarf that is separated by approximately 1,000 AUs
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
. It is uncertain whether they are gravitationally bound, but they do have a common motion through space and so the two stars probably share a common origin.
External links
- Theta Bootis by Professor Jim Kaler.