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 gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or ''galaxy'', although, broadly speakin ...

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 po ...

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 ...

. It has 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 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 lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...

measurements, it is located at a distance of 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 rad ...

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 or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. T ...

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 Eart ...

) comes from the

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walte ...

phrase ( ar, الفقرة الثالثة), a mis-transcription of ( ar, القفزة الثالثة), 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 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 ...

. In 2016, the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

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 List of proper names of stars, proper names for stars for the international astronomical community. It operates under ...

(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, (), meaning ''

Three Steps 3 is a number, numeral, and glyph. 3, three, or III may also refer to: * AD 3, the third year of the AD era * 3 BC, the third year before the AD era * March, the third month Books * '' Three of Them'' (Russian: ', literally, "three"), a 1901 ...

'', 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 me ...

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 star system 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 abbreviated Xi ...

. 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 oft ...

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

Apollo 1 Apollo 1, initially designated AS-204, was intended 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 orbita ...

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, pilot in the United States Air Force, and member of the Mercury Seven selected by National Aeronautics and Space Administration's (NASA) as Project Merc ...

as a practical joke.

Stellar system

The Iota Ursae Majoris system is composed of two sets of

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 ...

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 (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

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 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 stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...

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

red dwarf ''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave (TV channel), Dave since 2009, gaining a ...

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 space exploration, astronomy, skywatching and entertainment, with editorial teams based in the United States and United Kingdom. The website offers live coverage of space missions, astronomical discov ...

article
Talitha
by Professor Jim Kaler. {{Stars of Ursa Major Ursae Majoris, Iota 4 Ursa Major (constellation) 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