Alpha2 Canum Venaticorum variable

Variable star type

An Alpha2 Canum Venaticorum variable (or α2 CVn variable) is a type of variable star. These stars are chemically peculiar main sequence stars of spectral class B8p to A7p. They have strong magnetic fields and strong silicon, strontium, or chromium spectral lines. Their brightness typically varies by 0.01 to 0.1 magnitudes over the course of 0.5 to 160 days.[1]

A light curve for α2 Canum Venaticorum, plotted from TESS data[2]

In addition to their intensities, the intensities and profiles of the spectral lines of α2 CVn variables also vary, as do their magnetic fields. The periods of these variations are all equal and are believed to equal the period of rotation of the star. It is thought that they are caused by an inhomogeneous distribution of metals in the atmospheres of these stars, so that the surface of the star varies in brightness from point to point.[3]

The type-star which this class is named after is α2 Canum Venaticorum, a star in the binary system of Cor Caroli, which is in the northern constellation of Canes Venatici. Its brightness fluctuates by 0.14 magnitudes with a period of 5.47 days.[4]

## Examples

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This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by adding missing items with reliable sources.

List of Alpha2 Canum Venaticorum Variables[5] Designation (name) | Constellation | Discovery | Apparent magnitude (Maximum)  | Apparent magnitude (Minimum)  | Range of magnitude | Spectral type | Comment

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(α2 Canum Venaticorum) Cor Caroli | Canes Venatici |  | 2.84  | 2.98  | 0.14  | A0Vp(Si-Cr-Eu)  | Prototype
(ε UMa) Alioth | Ursa Major |  | 1.76  |  | 0.02  | A1III-IVp kB9(Cr-Eu)  | Brightest Member
α Dor | Dorado |  | 3.26  | 3.30  | 0.04  | B9IIIp(Si)  | One of the hottest; binary
α Psc (Alrescha)  | Pisces |  | 3.82  | 3.83  | 0.01  | A2IVp(Sr)  | Binary
β Hydrae A  | Hydra | 1834  | 4.67  | 4.71  | 0.04  | B8.5IIIp(Si)  | Hottest member;binary
HD 187474 | Sagittarius |  | 5.28  | 5.34  | 0.06  | A0 EuCrSr  | Long 6.4 year period;binary

## References

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1. ^ Variability types, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line August 20, 2008.
2. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
3. ^ pp. 83–85, Variable Stars, Michel Petit, foreword by Paolo Maffei, tr. from French by W. J. Duffin, Chichester, UK: John Wiley & Sons, 1987, ISBN 0-471-90920-3.
4. ^ alf 2 CVn , database entry, General Catalogue of Variable Stars Archived 2017-06-20 at the Wayback Machine, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line August 20, 2008.
5. ^ Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.

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Variable stars

Pulsating|

| Cepheids and
cepheid-like|

* Type I (Classical cepheids, Delta Scuti)
* Type II (BL Herculis, W Virginis, RV Tauri)
* RR Lyrae
* Rapidly oscillating Ap
* SX Phoenicis

|

Blue-white with
early spectra|

* Alpha Cygni
* Beta Cephei
* Slowly pulsating B-type
* PV Telescopii
* Blue large-amplitude pulsator

Long-period|

* Mira
* Semiregular
* Slow irregular

Other|

* Gamma Doradus
* Solar-like oscillations
* White dwarf

Eruptive|

| Protostar and PMS|

* Herbig Ae/Be
* Orion
* FU Orionis
* T Tauri

|

Giants and
supergiants|

* Luminous blue variable
* R Coronae Borealis (DY Persei)
* Yellow hypergiant

Eruptive binary|

* Double periodic
* FS Canis Majoris
* RS Canum Venaticorum

Other|

* Flare
* Gamma Cassiopeiae
* Lambda Eridani
* Wolf–Rayet

Cataclysmic|

* AM Canum Venaticorum
* Dwarf nova
* Luminous red nova
* Nova
* Polar
* Intermediate
* Supernova
* Hypernova
* SW Sextantis
* Symbiotic
* Symbiotic nova
* Z Andromedae

Rotating|

| Non-spherical|

* Rotating ellipsoidal

|

Stellar spots|

* BY Draconis
* FK Comae Berenices

Magnetic fields|

* α2 Canum Venaticorum
* Pulsar
* SX Arietis

Eclipsing|

* Algol
* Beta Lyrae
* Planetary transit
* W Ursae Majoris

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