Classical Cepheid variable
Designation ( name ) Constellation Maximum Apparent magnitude ( m V ) Minimum Apparent magnitude ( m V ) Period ( days ) Spectral class
η Aql Aquila 3 .48 4 .39 07.17664 F6 Ibv
FF Aql Aquila 5 .18 5 .68 04.47 F5Ia-F8Ia
TT Aql Aquila 6 .46 7 .7 13.7546 F6-G5
U Aql Aquila 6 .08 6 .86 07.02393 F5I-II-G1
T Ant Antlia 5 .00 5 .82 05.898 G5
RT Aur Auriga 5 .00 5 .82 03.73 F8Ibv
l Car Carina 3 .28 4 .18 35.53584 G5 Iab/Ib
δ Cep Cepheus 3 .48 4 .37 05.36634 F5Ib-G2Ib
AX Cir Circinus 5 .65 6 .09 05.273268 F2-G2II
BP Cir Circinus 7 .31 7 .71 02.39810 F2/3II-F6
BG Cru Crux 5 .34 5 .58 03.3428 F5Ib-G0p
R Cru Crux 6 .40 7 .23 05.82575 F7Ib/II
S Cru Crux 6 .22 6 .92 04.68997 F6-G1Ib-II
T Cru Crux 6 .32 6 .83 06.73331 F6-G2Ib
X Cyg Cygnus 5 .85 6 .91 16.38633 G8Ib
SU Cyg Cygnus 6 .44 7 .22 03.84555 F2-G0I-II
β Dor Dorado 3 .46 4 .08 09.8426 F4-G4Ia-II
ζ Gem Gemini 3 .62 4 .18 10.15073 F7Ib to G3Ib
V473 Lyr Lyra 5 .99 6 .35 01.49078 F6Ib-II
R Mus Musca 5 .93 6 .73 07.51 F7Ib-G2
Examples
Several classical Cepheids have variations that can be recorded with night-by-night , trained naked eye observation , including the prototype Delta Cephei in the far north , Zeta Geminorum and Eta Aquilae ideal for observation around the tropics ( near the ecliptic and thus zodiac ) and in the far south Beta Doradus . The closest class member is the North Star ( Polaris ) whose distance is debated and whose present variability is approximately 0.05 of a magnitude . [ 6 ]
Classical Cepheids (also known as Population I Cepheids, Type I Cepheids, or Delta Cepheid variables) are a type of Cepheid variable star. They are population I variable stars that exhibit regular radial pulsations with periods of a few days to a few weeks and visual amplitudes from a few tenths of a magnitude to about 2 magnitudes. There exists a well-defined relationship between a classical Cepheid variable's luminosity and pulsation period, securing Cepheids as viable standard candles for establishing the galactic and extragalactic distance scales. Hubble Space Telescope (HST) observations of classical Cepheid variables have enabled firmer constraints on Hubble's law. Classical Cepheids have also been used to clarify many characteristics of our galaxy, such as the local spiral structure and the Sun's height above the galactic plane. Around 800 classical Cepheids are known in the Milky Way galaxy, out of an expected total of over 6,000. Several thousand more are known in the Magellanic Clouds, with more known in other galaxies; the Hubble Space Telescope has identified some in NGC 4603, which is 100 million light years distant.