Star profile

21 Canum Venaticorum

Variable star

3D likeness based on its real data · class A · ~8,500 K

What is 21 Canum Venaticorum

21 Canum Venaticorum —also known as BK CVn— is a silicon star of the Alpha-2 Canum Venaticorum class: a peculiar variable type whose brightness shifts slightly as chemical patches rotate across its surface. Its variability —just 0.04 magnitudes over 18.4 hours— was discovered in 1984 by Juraj Zverko. A blue subgiant 277 light-years away with nearly three solar masses, it spins fast and shows how a star's magnetic imperfections can paradoxically become its most recognisable signature.

Where it is and when to see it

21 Canum Venaticorum lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is March, when it culminates around midnight.

From London it never sets and culminates about 88° up.
From New York it never sets and culminates about 81° up.
From Sydney it culminates about 6° above the horizon.

It can be seen from anywhere north of 40° S.

It ranks no. 11 in brightness among the 33 stars of Canes Venatici in our catalogue. To find it, start from Cor Caroli, the brightest: it lies about 12° away (a fist at arm's length covers about 10°).

The light you see today left it about 270 years ago.

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Astronomical data for 21 Canum Venaticorum

Constellation: Canes Venatici
Apparent magnitude: 5.14
Distance: 274.8 light years
Coordinates (J2000): RA 199.561° · Dec 49.682°
Catalogue: HIP 64906 · HD 115735

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Other stars in Canes Venatici

Canes Venatici has 33 stars in Stelvia's catalogue. Here are a few of them.

See all 33 stars in Canes Venatici