Alpha 2 -Canum Venaticorum Star

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An Alpha 2 -Canum Venaticorum star ( α 2 -CVn star or α 2 -CVn variable ) is a rotationally variable star . In addition to the variability, stars of this type show chemical abnormalities in their emission spectrum and belong to the spectral class A7p to B8p (p = " peculiar / noticeable ", see also Ap star ). They have a strong magnetic field . The emission spectrum shows pronounced lines of silicon , strontium and chromium . Many stars of this type have a mass in the range of 3 to 4 solar masses .

Their brightness typically fluctuates between 0.01 and 0.1 mag over a cycle of 0.5 to 160 days. Just like the brightness, the strength of the magnetic field also fluctuates. There are regularly recurring changes in the composition of the emission spectrum. Relationships with the star's period of rotation could be established. It has so far been assumed that an inhomogeneous distribution of metals in the star's atmosphere is responsible for this. This leads to uneven distribution of brightness in the photosphere of the star.

The eponymous star is the second component of the Cor Caroli binary star system . The second component is called α 2 Canum Venaticorum . Its brightness fluctuation is 0.14 mag with a period of 5 days and 11 hours.

Occurrence in star catalogs

The General Catalog of Variable Stars currently lists around 400 stars with the abbreviations ACV or ACVO , which means that around 1% of all stars in this catalog belong to the class of α 2 -canum venaticorum stars.

Examples

Individual evidence

  1. ↑ a b Variability types, General Catalog of Variable Stars , Sternberg Astronomical Institute, Moscow, Russia. Retrieved February 2, 2019.
  2. ↑ pp. 83-85, Variable Stars , Michel Petit, foreword by Paolo Maffei, tr. From French by WJ Duffin, Chichester, UK: John Wiley & Sons, 1987
  3. ↑ alf 2 CVn, database entry, General Catalog of Variable Stars , Sternberg Astronomical Institute, Moscow, Russia. Retrieved August 21, 2018.