Iota Ursae Majoris (ι Ursae Majoris, abbreviated Iota UMa, ι UMa), also named Talitha , is a

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravity, gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally calle ...

in the northern

circumpolar constellation A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest p ...

Ursa Major Ursa Major, also known as the Great Bear, is a constellation in the Northern Sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear", referring to and contrasting it with nearby Ursa M ...

. It has an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...

of 3.14, making it visible to the naked eye and placing it among the brighter members of this constellation. Based upon

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements, it is located at a distance of from the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

Nomenclature

''ι Ursae Majoris'' ( Latinised to ''Iota Ursae Majoris'') is the star's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...

The traditional name ''Talitha'', (which was shared with

Kappa Ursae Majoris Kappa Ursae Majoris (κ Ursae Majoris, abbreviated Kappa UMa, κ UMa) is a binary star in the constellation of Ursa Major. With a combined apparent magnitude of +3.60, the system is approximately 358 light-years from Earth ...

) comes from the

Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...

phrase (), a mis-transcription of (), which means "the third spring, or leap, of the ghazal".Richard Hinckley Allen :Star Names — Their Lore and Meaning - Ursa Major, the Greater Bear
/ref> The term ''Borealis'' meaning "the north side" in

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

. In 2016, the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included ''Talitha'' for this star. In

Chinese Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethnic ...

, (), meaning ''

Three Steps The Three Steps are three prominent rocky steps on the northeast ridge of Mount Everest. They are located at altitudes of , , and . The Second Step is especially significant both historically and in mountaineering terms. Any climber who wants to ...

'', refers to an asterism consisting of ι Ursae Majoris,

Lambda Ursae Majoris Lambda Ursae Majoris (λ Ursae Majoris, abbreviated Lambda UMa, λ UMa), formally named Tania Borealis , is a star in the northern circumpolar constellation of Ursa Major. Properties This star has an apparent visual magnit ...

Mu Ursae Majoris Mu Ursae Majoris (μ Ursae Majoris, abbreviated Mu UMa, μ UMa), formally named Tania Australis , is a binary star in the constellation of Ursa Major. An apparent visual magnitude of +3.06 places it among the brighter mem ...

Nu Ursae Majoris Nu Ursae Majoris (ν Ursae Majoris, abbreviated Nu UMa, ν UMa), formally named Alula Borealis , is a double star in the northern circumpolar constellation of Ursa Major. At an apparent visual magnitude of +3.490, it is br ...

and

Xi Ursae Majoris Xi Ursae Majoris is a quintuple star system away in the constellation of Ursa Major. It has the traditional name Alula Australis; ''Xi Ursae Majoris'' is the Bayer designation, which is Latinised from ξ Ursae Majoris and abbre ...

. Consequently, the

Chinese name Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethni ...

for ι Ursae Majoris itself is (, ).(Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 21 日
The star was also dubbed ''Dnoces'' ('Second,' backwards) after Edward H. White II, an

Apollo 1 Apollo 1, initially designated AS-204, was planned to be the first crewed mission of the Apollo program, the American undertaking to land the first man on the Moon. It was planned to launch on February 21, 1967, as the first low Earth orbital ...

astronaut. The name was invented by his fellow astronaut

Gus Grissom Virgil Ivan "Gus" Grissom (April 3, 1926 – January 27, 1967) was an American engineer and pilot in the United States Air Force, as well as one of the original Mercury Seven selected by the NASA, National Aeronautics and Space Administration fo ...

as a practical joke.

Stellar system

The Iota Ursae Majoris system is composed of two sets of

binary star A binary star or binary star system 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 as separate stars us ...

s. The two binary systems orbit around each other once every 2,084 years. The apparent separation between the two binaries is rapidly decreasing as they follow their orbits. In 1841 when the B component was first discovered, they had a separation of 10.7

arcsecond A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

s, or at least 156 AU. By 1971 their separation had decreased to 4.5

s, or at least 66 AU. This system appears to be dynamically unstable with a high likelihood and may become disrupted on a time scale on the order of 10⁵ years. The brightest component is a white A-type

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 ...

. It is a member of a

spectroscopic binary A binary star or binary star system 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 as separate stars us ...

system whose components have an orbital period of 4,028 days. The companion, which has not been directly observed, is thought to be a

white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

with a mass of . The companion binary is composed of the 9th magnitude and 10th magnitude stars, both of which are

red dwarf A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...

s. These two red dwarfs, designated Iota Ursae Majoris B and C respectively, orbit around each other with a period of 39.7 years, and are separated by roughly 0.7

s, or at least 10 AU. This pair may be the source of the X-ray emission detected from this system.

References

External links

NightSky Friday: Rotanev, Derf, Navi, and other Backward Star Names
–

Space.com Space.com is an online publication focused on outer space, space exploration, astronomy, skywatching and entertainment, with editorial teams based in the United States and United Kingdom. Launched on July 20, 1999, the website offers live coverag ...

article
Talitha
by Professor Jim Kaler. {{Stars of Ursa Major Ursae Majoris, Iota 4 Ursa Major F-type subgiants Spectroscopic binaries Talitha Ursae Majoris, 09 M-type main-sequence stars 0331 044127 3569 076644 Durchmusterung objects

Nomenclature

Stellar system

See also

References

External links