Alpha Camelopardalis, Latinized from α Camelopardalis, is a

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

in the northern constellation of

Camelopardalis Camelopardalis is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative fo ...

. With 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 4.3, it is the third-brightest star in this not-very-prominent

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 ...

; the first and second-brightest stars being Beta Camelopardalis and CS Camelopardalis, respectively. It is the farthest constellational star, with a distance of approximately 6,000

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 101 ...

s from Earth based on

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.

Description

Alpha Camelopardalis has a

stellar classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...

of O9 Ia, with the 'Ia' indicating that it is an O-type luminous supergiant. It is a massive star with 37.6 times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of ...

and 32.5 times the Sun's radius. The

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of the outer envelope is 29,000 K; much hotter than the Sun's effective temperature of 5,778 K, giving it the characteristic blue hue of an O-type star. It is emitting 676,000 times the

luminosity of the Sun The solar luminosity (), is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nomin ...

and is a weak X-ray emitter. Variations in the profiles of Alpha Camelopardalis' spectral lines are caused by fluctuations in the

photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...

and

stellar wind A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric. ...

. This may be caused by non-radial pulsations. The

absorption line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to ident ...

s in the optical spectrum show radial velocity variations, although there is significant uncertainty about the period. Estimates range from a period as low as 0.36 days up to 2.93 days. The

from this star is not smooth and continuous, but instead shows a behavior indicating clumping at both large and small scales. This star is losing mass rapidly through its stellar wind at a rate of approximately 6.3 × 10⁻⁶

solar mass The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass o ...

es per year, or the equivalent of the mass of the Sun every 160,000 years. In 1968, this star was classified as a spectroscopic binary, indicating that it has an orbiting stellar companion with a period of 3.68 days and an

orbital eccentricity In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values b ...

of 0.45. Subsequent studies refined the period to 3.24 days. However, in 2006 it was recognized that the changes in the spectrum were probably the result of changes in the atmosphere or stellar wind, so it is more likely a single star. Speckle interferometry observations with the

3.67 m Advanced Electro Optical System Telescope The 3.67 m Advanced Electro Optical System Telescope is a Department of Defense telescope at Haleakala Observatory. The telescope is part of the Maui Space Surveillance Complex (MSSC), which in turn is part of the Air Force Maui Optical and Su ...

at the Haleakala Observatory failed to detect a secondary component. In 1961, based on the criteria that the

proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...

of this star indicates a space velocity of greater than 30 km/s, Alpha Camelopardalis was suggested as a candidate runaway star that had been ejected from the cluster

NGC 1502 NGC 1502 is a young open cluster of approximately 60 stars in the constellation Camelopardalis, discovered by William Herschel on November 3, 1787. It has a visual magnitude of 6.0 and thus is dimly visible to the naked eye. This cluster is loca ...

. This was based upon the kinematic properties of the star and cluster, as well as the location of this star at a high galactic latitude in an area otherwise lacking in

stellar association A stellar association is a very loose star cluster, looser than both open clusters and globular clusters. Stellar associations will normally contain from 10 to 100 or more stars. The stars share a common origin, but have become gravitationally ...

s. Over the course of a million years, this star should have moved only 1.4° across the sky, while it was estimated as being only two million years old. Runaway stars such as this with a stellar wind that is moving at supersonic velocity through the

interstellar medium In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstella ...

have their wind confined by a bow shock due to

ram pressure Ram pressure is a pressure exerted on a body moving through a fluid medium, caused by relative bulk motion of the fluid rather than random thermal motion. It causes a drag force to be exerted on the body. Ram pressure is given in tensor form as ...

. The dust in this bow shock can be detected using an

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from aroun ...

telescope. Just such a bow shock was observed with NASA's Wide-field Infrared Survey Explorer, or WISE. The star is traveling at a rate of somewhere between 680 and 4,200 kilometers per second: between 1.5 and 9.4 million mph.

Chinese name

In Chinese, (), meaning '' Right Wall of Purple Forbidden Enclosure'', refers to an asterism consisting of α Camelopardalis, α Draconis, κ Draconis, λ Draconis, 24 Ursae Majoris, 43 Camelopardalis and

BK Camelopardalis BK Camelopardalis is a variable star in the northern circumpolar constellation of Camelopardalis, near the constellation border with Cassiopeia. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magn ...

. 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 α Camelopardalis itself is (, en, the Sixth Star of Right Wall of Purple Forbidden Enclosure.), representing (), meaning ''Second Imperial Guard''.English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name
, Hong Kong Space Museum. Accessed on line November 23, 2010 少衛 (Shǎowèi) is westernized into Shaou Wei by R. H. Allen, the meaning is "Minor Guard", but it is not clearly designated.

References

External links

HR 1542
entry in the

Bright Star Catalogue The Bright Star Catalogue, also known as the Yale Catalogue of Bright Stars, Yale Bright Star Catalogue, or just YBS, is a star catalogue that lists all stars of stellar magnitude 6.5 or brighter, which is roughly every star visible to the na ...

Alpha Camelopardalis
in

Aladin Aladdin is a folk tale of Middle Eastern origin. Aladdin, Aladin, and variants such as Aladdin and His Magic Lamp, may also refer to: Arts and entertainment Disney franchise * Aladdin (franchise), ''Aladdin'' (franchise) ** Aladdin (Disney chara ...

Image of the constellational matrix formed by viewing the constellational lines at 16,000 light-years from the sun. Spike at the left is Alpha Camelopardalis.
{{DEFAULTSORT:Alpha Camelopardalis O-type supergiants Emission-line stars Runaway stars Camelopardalis (constellation) Camelopardalis, Alpha BD+66 0358 Camelopardalis, 09 030614 022783 1542