·       Stars type Algol (name of star prototipe Algol,  Persei) : both members have a spherical shape and the periods is comprised in a  broad time interval, generally from 2 to 3 days or from 5 to 8. You distinguish a main minimum and a secondary minimum very small (undetectable). Star remains for almost all its time in its brightness.

·       Stars type  Lyrae, in which the two components are so near to approach an elissoidal shape (due to proddings of tides) and they can be in contact; the two stars have different dimensions. The period is greater than a day: continued brightness variations with periodicity of minimums that are very deep and not much deep.

·        Stars type W Ursae Majoris, the which components have an elissoidal shape, but with equal dimensions (midget dimensions) and they’re almost in contact. Period that is lower than a day.

Around the 90% of Eclipse, variables has periods lower than 10 days, even though there are stars with periods very long (for example the 9883 days of  Aurigae);  some stars have lower periods to 0,2 days: the SX Phoenicis (79 minutes) is the lowest period.

·   Stars type  Canis Majoris o  Cephei : giants or subgiants spectral type between B0 and B3 with period comprised between 3 and 6 hours; the width of variations varies from 0,1 to 0,3 magnitudes; they’re evolved stars that run out their hydrogen reserve in the nucleus.

·   Stars type Mira : their name is also variables long period, their prototype is Mira Ceti ( Ceti), it’s the brightest star of this class and is the first variable that was discovered. This type of stars are giants that belong to spectral types M, S, N, and R1 with period comprised between 80 and 1000 days, with width of variations between 2,5 and 6 magnitude; the middle absolute magnitudes are comprised between +2 and -2 and the variations can be very big, for example:  Cygni varies 11 magnitudes. The spectrums have emission lines, many of these stars can be binary systems.

·   half –regular Variables : these types are giants and supergiants, spectral type advanced with not-regular period, (sometimes they are so unspecified to be unricognizable). Antares and Betelgeuse belong to this group. The widths are lower than Mira Type, the periods are comprised between about 30 and about 1000 days. There are different subdivision in subtypes (SRa, SRb, SRc, SRd), for the spectral type and the regularity of period.

·   Stars type RV Tauri : they’re supergiant stars with high brightness, spectral type F, G, or K, M is rarely; periods between 50 and 150 days, width 3 magnitudes; they alternate deep minimum and low deep minimum. They are divided in subtypes on the strength of the great or low regularity.

·   Stars type ₂ Canum Venaticorum: variations in intensity of determinate spectral lines and of  magnetic field, small variations in pulsations and in radial velocity.

·   irregular Variables: giants and supergiants with light curves completely irregular. The widths are lower to 2 magnitudes, on average 0,5 magnitudes.

·   Stars type ZZ Ceti : white pulsating dwarfs, with periods that can be short to be 30 seconds (the longest periods aren’t longer of 30 minutes) and widths lower to 0,2 magnitudes. Sometimes you can observe flares due to interactions with a companion very near to them.

·     Dwarf Novae : they are called U Geminorum or SS Cygni. After a balance period they show in few days a raise of brightness between 2 and 6 magnitudes, while the return to normality you get in 10-15 days. There isn’t any periodicity in variations of magnitude: the gap between a raise and the subsequent lasts between 10 days and some years. In this case stars are a red dwarf and a white dwarf too, the cause of variation is the same of real novae but on lowered scale. They are called Cataclysmic Variable too.

·     Stars type SU Ursae Majoris: they are similar to dwarf novae, have ordinary maximum and “supermaximum” greater size.

·     Stars type Z Camelopardalis: similar to early stars, but sometimes the brightness has a intermediary level between minimum and maximum for periods that have unpredictable duration.

·     Novoidi Variables: they are different stars, but their explosions are fairly similar to real novae. The main types are:

·     Stars type  Cassiopeiae: spectral type B; with a speed rotation, they have in the spectrums emission parts, they lose mass in equatorial region, their evolution bring them to exit out of the main sequence. They have small variation size, lower to 2 magnitudes.

·     Stars type Z Andromedae: they are called also stars simbiotiche; they are binary very narrow and often inner a common nebula. One of two factors is a red cold star, while the other star is so warm; the variations are caused by pulsations of red star and at the same time by interactions between two stars.

·     Stars type RR Telescopii: they show slow raise of brightness, that it can consist in a transition towards state of planetary nebula.

·     Stars type S Doradus : absolute magnitudes -10, spectrums from B to F, widths of variations between 1 and 3 magnitudes that can be cyclic or irregular. In fact in the last years you decided that 30 Doradus isn’t a star; however you can refer an object to this class like P Cygni.

·     Supernovae : about this distinguishing class of variables, we speak about apart (see M1 in Taurus constellation).

·     Stars type R Coronae Borealis: big stars, that for a long time they keep steady brightness, that sometimes it decreases of many magnitudes, returning then to original worth. We didn’t manage to highlight a periodicity in the phenomenon. They are poor of hydrogen, but rich of carbon, they belong to spectral types F, G, K or R. The wideness of almost 10 magnitudes are big and the weakening is due to “caligine” clouds that accumulate themselves in star atmosphere.

·     Variable stars in the nebula: irregular variations of brightness, with widths of variation between 1 and 4 magnitude. There are different types:

·     Stars type T Orionis: spectrums from B to K, small mass and irregular variations;

·     Stars type RW Aurigae: similar, but they’re not associated to nebulas, widths from 0,5  to 1 magnitude and periods from some hours to some days;

·     Stars type T Tauri: variables extremely young, but they aren’t in the main sequence (protostars), irregular variations that have a small width;

·     Stars type FU Orionis: spectrums between A and F, that can raise the brightness of many magnitudes in few months and preserve themselves for some decades; during the maximum they have lines in emissions.

·     Stars type UV Ceti: red dwarfs that show sudden raise of brightness that goes on few minutes or at most few hours and that return quickly to normal polishing. The increase of polishing is included between 1 and 6 magnitudes. They are divided in flare stars and flash stars. These last stars are bonded to clouds composed by interstellar material and they were observed in the associations T Tauri. A well-known flare star is Proxima Centauri, the nearest star to sun.