Iota Ursae Majoris

Encyclopedia : I : IO : IOT : Iota Ursae Majoris

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|- ! style="background-color: #FFFFC0;" colspan="2" | Details |- |style="vertical-align: baseline;" | Mass | M_☉ |- |style="vertical-align: baseline;" | Radius | R_☉ |- |style="vertical-align: baseline;" | Luminosity | L_☉ |- |style="vertical-align: baseline;" | Temperature | K |- |style="vertical-align: baseline;" | Metallicity | |- |style="vertical-align: baseline;" | Rotation | |- |style="vertical-align: baseline;" | Age | })<()or(}})=()and(}})<())}}} years

|- ! style="background-color: #FFFFC0;" colspan="2" | Other designations |- | colspan="2" |

|} Iota Ursae Majoris (ι UMa / ι Ursae Majoris) is a star system in the constellation Ursa Major. It is approximately 47.7 light years from Earth. It has the traditional names Talitha Borealis and Alphikra Borealis, and was also named Dnoces ("Second," backwards) after Edward H. White II, an Apollo 1 astronaut. The name was invented by his fellow astronaut Gus Grissom as a practical joke.

The Iota Ursae Majoris system is composed of two binary stars. The brightest component, Iota Ursae Majoris A, is a white A-type subgiant with an apparent magnitude of +3.12. It is a spectroscopic binary whose components have an orbital period of 4028 days.

The companion binary is composed of the 9th magnitude Iota Ursae Majoris B and the 10th magnitude Iota Ursae Majoris C. These two stars orbit around each other with a period of 39.7 years, and are separated by roughly 0.7 arcseconds, or at least 10 Astronomical Units (AU). The two binary systems orbit around each other once every 818 years. The 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 arcseconds, or at least 156 AU. By 1971 their separation had decreased to 4.5 arcseconds, or at least 66 AU.

External links

• [NightSky Friday: Rotanev, Derf, Navi, and other Backward Star Names] – Space.com article
• [ARICNS]
• [Alcyone emphemeris]
• [Talitha] by Professor Jim Kaler.

 

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