Iota Ursae Majoris
Encyclopedia
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, 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 star
s. 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 AU
. The two binary systems orbit around each other once every 818 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 arcseconds, or at least 156 AU. By 1971 their separation had decreased to 4.5 arcseconds, or at least 66 AU.
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...
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....
Ursa Major
Ursa Major
Ursa Major , also known as the Great Bear, is a constellation visible throughout the year in most of the northern hemisphere. It can best be seen in April...
. It is approximately 47.7 light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
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...
. It has the traditional names Talitha, Talitha Borealis and Alphikra Borealis, and was also named Dnoces ("Second," backwards) after Edward H. White II
Edward Higgins White
Edward Higgins White, II was an engineer, United States Air Force officer and NASA astronaut. On June 3, 1965, he became the first American to "walk" in space. White died along with fellow astronauts Gus Grissom and Roger Chaffee during a pre-launch test for the first manned Apollo mission at...
, an Apollo 1
Apollo 1
Apollo 1 was scheduled to be the first manned mission of the Apollo manned lunar landing program, with a target launch date of February 21, 1967. A cabin fire during a launch pad test on January 27 at Launch Pad 34 at Cape Canaveral killed all three crew members: Command Pilot Virgil "Gus"...
astronaut. The name was invented by his fellow astronaut Gus Grissom
Gus Grissom
Virgil Ivan Grissom , , better known as Gus Grissom, was one of the original NASA Project Mercury astronauts and a United States Air Force pilot...
as a practical joke.
The Iota Ursae Majoris system is composed of two binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
s. The brightest component, Iota Ursae Majoris A, is a white A-type
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...
subgiant with an apparent magnitude
Apparent 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...
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 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
. The two binary systems orbit around each other once every 818 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 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.comSpace.comSpace.com is a space and astronomy news website. Its stories are often syndicated to other media outlets, including CNN, MSNBC, Yahoo!, and USA Today.Space.com was founded by former CNN anchor Lou Dobbs and Rich Zahradnik, in July 1999...
article - ARICNS
- Talitha by Professor Jim Kaler.