Mira variables, named after the star Mira (IPA: /ˈmairə/), are a class of pulsating variable stars characterized by very red colors, pulsation periods longer than 100 days, and light amplitudes greater than one magnitude. They are red giant stars in the very late stages of stellar evolution (the asymptotic giant branch) that will expel their outer envelopes as planetary nebulae and become white dwarfs within a few million years. Chandra X-ray Image of Mira Mira (ο Cet / 68 Ceti / HD14386 / HIP10826 / ADS 1778 AP / Omicron Ceti) is a binary star in the constellation Cetus consisting of the red giant, Mira A or just Mira, and a white dwarf, Mira B or VZ Ceti. ... This article or section contains a plot summary that is overly long or excessively detailed. ... The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... According to the Hertzsprung-Russell diagram, a red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giant stars. ... Projected timeline of the Suns life In astronomy, stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. ... A period of Stellar evolution undertaken by all low to intermediate mass stars (0. ... NGC 6543, The Cats Eye Nebula NGC 6853, The Dumbbell Nebula A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. ... This article or section does not adequately cite its references or sources. ...

Mira variables are believed to be stars with less than two solar masses, but can be thousands of times more luminous than the Sun due to their very large, distended envelopes. They are believed to be pulsating due to the entire star expanding and contracting. This produces a change in temperature along with radius, both of which factors cause the variation in luminosity. The pulsation period is a function of the mass and radius of the star. Early models of Mira stars assumed that the star remained spherically symmetric during this process (largely to keep the computer modelling simple, rather than for physical reasons). A recent survey of Mira variable stars found that 75% of the Mira stars which could be resolved using the IOTA telescope are not spherically symmetric^[1], a result which is consistent with previous images of individual Mira stars (e.g. ^[2], ^[3], ^[4]), so there is now pressure to do realistic three dimensional modelling of Mira stars on supercomputers. In astronomy, the solar mass is a unit of mass used to express the mass of stars and larger objects such as galaxies. ... This article does not cite any references or sources. ... Sol redirects here. ... This article does not cite any references or sources. ... The Infrared Optical Telescope Array (IOTA) began with an agreement in 1988 among five Institutions, the Smithsonian Astrophysical Observatory, Harvard University, the University of Massachusetts, the University of Wyoming, and MIT/Lincoln Laboratory, to build a two-telescope stellar interferometer for the purpose of making fundamental astrophysical observations, and also...

Though most Mira variables share many similarities in behavior and structure, they are a heterogeneous class of variables due to differences in age, mass, pulsation mode, and chemical composition. For example, many, such as R Leporis have spectra dominated by carbon, suggesting that material from the core of the star has been transported to the surface. This material often forms dust shrouds around the star, which also contribute to periodic dimming and brightening. A few Mira variables are also known to be natural maser sources. Hinds Crimson Star, also known as R Leporis, is a well-known variable star, in the constellation Lepus, near the border with Eridanus. ... The visible spectrum is the portion of the optical spectrum (light or electromagnetic spectrum) that is visible to the human eye. ... For other uses, see Carbon (disambiguation). ... Look up dust in Wiktionary, the free dictionary. ... An astrophysical maser is a naturally occurring source of stimulated spectral line emission, typically in the microwave portion of the electromagnetic spectrum. ...

A small subset of Miras appear to change their period over time -- the period increases or decreases by a substantial amount (up to a factor of three) over the course of several decades to a few centuries. This is believed to be caused by thermal pulses, where a shell of hydrogen near the core of the star becomes hot and dense enough to undergo nuclear fusion. This changes the structure of the star, which manifests itself as a change in period. This process is predicted to happen to all Mira variables, but the relatively short duration of thermal pulses (a few thousand years) over the asymptotic giant branch lifetime of the star (a few million years), means we only see it in a few of the several thousand Mira stars known. However, most Mira variables exhibit slight cycle-to-cycle changes in period, probably caused by nonlinear behavior in the stellar envelope including deviations from spherical symmetry. The orbital period is the time it takes a planet (or another object) to make one full orbit. ... The proton-proton chain reaction is one of two fusion reactions by which stars convert hydrogen to helium, the other being the CNO cycle. ... A period of Stellar evolution undertaken by all low to intermediate mass stars (0. ...

Mira variables are popular targets for amateur astronomers interested in variable star observations, because of their dramatic changes in brightness. Some Mira variables (including Mira itself) have reliable observations stretching back well over a century. It has been suggested that this article or section be merged with Skygazing. ... This article or section contains a plot summary that is overly long or excessively detailed. ... Chandra X-ray Image of Mira Mira (ο Cet / 68 Ceti / HD14386 / HIP10826 / ADS 1778 AP / Omicron Ceti) is a binary star in the constellation Cetus consisting of the red giant, Mira A or just Mira, and a white dwarf, Mira B or VZ Ceti. ...

References

1. ^ First Surface-resolved Results with the IOTA Imaging Interferometer: Detection of Asymmetries in AGB stars, 2006
2. ^ Optical aperture synthetic images of the photosphere and molecular atmosphere of Mira, 1992
3. ^ Asymmetries in the atmosphere of Mira, 1991
4. ^ Surface imaging of long-period variable stars, 1999