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 Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

as a faint, blue-white hued star with an apparent visual magnitude that fluctuates around 4.74. The star is located approximately 540

light year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s away from the Sun based on

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 ...

. It is a proposed member of the Cassiopeia–Taurus group of co-moving stars.

Description

This is a

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

Be star with a stellar classification of B2.5 Vne, where the 'n' suffix indicates "nebulous" (broad) lines due to rapid rotation. The presence of emission lines in the

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

has been known since at least 1895.

Spectrogram A spectrogram is a visual representation of the spectrum of frequencies of a signal as it varies with time. When applied to an audio signal, spectrograms are sometimes called sonographs, voiceprints, or voicegrams. When the data are represen ...

s of the star have been taken since 1905, providing a long history of its cycles of variation. It ranges in brightness from a peak of 4.76 down to 4.90. BK Camelopardalis is 32 million years old and is spinning with a

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bu ...

of 328 km/s. It has 7.5 times the mass of the Sun and four times the Sun's radius. The star is radiating 1,081 times the luminosity of the Sun from its photosphere at an

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 18,720 K. This star lies at the center of a circular, disk-like structure spanning 1.4°, which may be a "magnetic funnel-like structure" that is emitting in the radio band. Neutral hydrogen along the trajectory of this star has been found to be deficient, which may be the result of

ionizing radiation Ionizing (ionising) radiation, including Radioactive decay, nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionization, ionize atoms or molecules by detaching ...

from the star. Two stars have been resolved close to BK Camelopardalis. The first, designated Ab, is separated by about 0.13 arcseconds. If it is physically associated with BK Camelopardalis, it would have an orbital period of several decades. The second star is designated as B but is likely an optical pair with the central BK Camelopardalis; that is, a chance alignment.

Chinese name

In Chinese, (), meaning '' Right Wall of Purple Forbidden Enclosure'', refers to an asterism consisting of BK Camelopardalis, α Draconis, κ Draconis, λ Draconis, 24 Ursae Majoris, 43 Camelopardalis and α Camelopardalis. Consequently, BK Camelopardalis itself is known as (, .) representing (), meaning ''First Prime Minister''.

References

External links

HR 985

CCDM J03201+6540

Image BK Camelopardalis
{{DEFAULTSORT:BK Camelopardalis B-type main-sequence stars Be stars Camelopardalis Durchmusterung objects 020336 015520 0985 Camelopardalis, BK