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Topic: Mira variables

	Mira variable
		Mira stars, also known as long-period variables, are named for their prototype, Mira (Omicron Ceti).
		Mira stars have masses similar to that of the Sun but, owing to their much greater size, have a feeble gravitational hold on the material in their outer layers which, as a consequence, escapes into space in the form of a strong stellar wind at a rate of about 10
		The rate of mass loss is such that the Mira stage can only last about a million years before the aging star evolves to become a white dwarf surrounded by a planetary nebula.
	www.daviddarling.info /encyclopedia/M/Mira_variable.html (234 words)

	AAVSO: AAVSO Section
		Variable stars need to be systematically observed over decades in order to: determine the long-time behavior of a star, provide professional astronomers with data needed to analyze variable star behavior, to schedule observations of certain stars, to correlate data from satellite and ground-based observations, and to make computerized theoretical models of variable stars.
		Cepheid Variables have played a pivotal role in determining distances to far away galaxies and the age of the universe.
		Other famous stars include the Mira variables, or the long period variable stars, and eclipsing binaries such as Algol (the demon star) in Perseus.
	www.aavso.org /vstar (377 words)

	Mira Information from AAVSO
		(See the December 1998 VSOTM for Mira.) Such variables are found in the high luminosity portion of the asymptotic giant branch (AGB) in the H-R diagram, along with the semiregular variable stars.
		Mira stars tend to be of spectral type M, S, and C, and with lengthy periods of 80 to 1000 days, these stars (along with their semiregular relatives) are referred to as long period variables.
		Mira stars are seen to vary in the visual regime by 2.5 magnitudes or more, and by more than 1 magnitude in the infrared (Mattei 1997).
	isi.ssl.berkeley.edu /aavso_mira_information.htm (1020 words)

	AAVSO: History Of Mira's Discovery
		Hence she concluded that a Mira-type variable could be discovered from the observation of a single spectrum plate—a quick discovery in comparison with painstaking intercomparisons of many chart plates.
		Table 5 shows by century the proliferation of discovery of Mira-type variables from 1596 through 1996, and adds the total numbers of all types of variables (excluding novae), and the percentage of all variables that are Mira type.
		Still the most numerous of all the different types of known variables, their rate of discovery is declining, whereas the advent of photoelectric photometry has produced much higher rates of discovery of stars of such Bsmall amplitude that they could not have been discovered by the older visual and photographic techniques.
	www.aavso.org /vstar/vsots/mirahistory.shtml (6002 words)

	AAVSO: Variable Star of the Month, Mira
		Mira, a cool red giant, is one of the most popular stars in the AAVSO observing program.
		During the 85th annual meeting of the AAVSO a special session was organized to celebrate the 400th anniversary of the discovery of Mira.
		The history of the discovery of Mira-type variables illustrates that (1) some new discoveries are re-discoveries of objects previously assumed to be novae; and (2) apparently logical deductions that early observations of a guest star correspond to a later discovered Mira-type may nevertheless be wrong.
	www.aavso.org /vstar/vsots/1298.shtml (645 words)

	Mike's Mira Stars
		Mira stars, or Long-Period Variables, are among the most numerous of all variable stars.
		Like many of my favourite Miras, BU Cyg has quite a short period, 158 days in this case, and is amazingly easy to find near a brilliant group of tenth-magnitude stars, themselves close to another band of even brighter ones.
		This was one of the first telescopic variables I ever observed, and it has the added advantage of being near the Hercules Cluster.
	ourworld.compuserve.com /homepages/silmerina/miras.htm (1136 words)

	Mira (Site not responding. Last check: )
		Mira variables vary in brightness by typically 5 to 6 magnitudes, but sometimes as much as 9 magnitudes.
		The variation in the brightness of Mira is accompanied by changes in temperature and spectral type.
		The long period variable is actually Mira A. There is a companion, Mira B, that is much smaller in size than A. The companion is a blue type B dwarf, that revolves in a 400 year orbit about A at a distance of more than 100 AU.
	domeofthesky.com /clicks/mira.html (391 words)

	Mira (Site not responding. Last check: )
		Mira, its very name telling us that we should take strong notice, Mira "the amazing one," the word coming from the same root as "miracle," Mira the only proper-named star in the sky that for a time is too faint to be seen with the naked eye.
		Mira itself was relegated by Johannes Bayer to be the "Omicron" (the 15th letter in the Greek alphabet) star.
		Mira is the brightest of the red class M "long period variables," thousands of which are now known.
	www.astro.uiuc.edu /~kaler/sow/mira.html (475 words)

	Mira variable - Wikipedia, the free encyclopedia
		Mira variables 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.
		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.
		Mira variables are popular targets for amateur astronomers interested in variable star observations, because of their dramatic changes in brightness.
	en.wikipedia.org /wiki/Mira_variable (581 words)

	Binary and Variable Stars
		A variable star, on the other hand, is a star that, for one reason of another, changes its luminosity in either a predictable pattern or at random.
		Mira Variables are named after the most famous Mira variable, Mira, in the constellation the Cetus, the Whale.
		Unlike Mira variables, the Cephied variable stars have extremely regular, and their cycles are directly linked to their absolute magnitude - the true measure of a star's brightness.
	filer.case.edu /~sjr16/stars_binvar.html (990 words)

	Variable Stars (Site not responding. Last check: )
		For the Cepheid variables, the period of variation is an indication of the absolute magnitude of the star.
		The extraordinary brightening of a star known as a nova is thought to be a characteristic of binary systems where there is exchange of mass, perhaps falling into a white dwarf and triggering a sudden burst of fusion.
		A pattern of regular intensity variation may signal the presence of a binary star or a multiple star system where eclipsing is taking place.
	hyperphysics.phy-astr.gsu.edu /hbase/starlog/varstar.html (202 words)

	Mira - Search Results - MSN Encarta
		Mira, also known as Mira Ceti and Omicron Ceti, a variable star in the constellation Cetus, the Whale.
		Mira Bai (1500-1550), a princess of Rājasthān, an area in northwest India, celebrated for her lyrical poetry and compositions of bhajans (songs of...
		- red giant star: a variable red giant in the constellation Cetus that is only visible a few weeks a year when it becomes the brightest star in the constellation
	ca.encarta.msn.com /Mira.html (114 words)

	Variable star Summary
		Cepheid variable stars are pulsating variables that possess a very significant characteristic; in the early 1900s Henrietta Leavitt and Harlow Shapley found that the speed at which they pulsate is directly related to the their brightness.
		Mira itself, also known as ο Ceti, varies in brightness from almost 2nd magnitude to as faint as 10th magnitude with a period of roughly 332 days.
		Variability of T Tauri stars is due to spots on the stellar surface and gas-dust clumps, orbiting in the circumstellar disks.
	www.bookrags.com /Variable_star (4064 words)

	Gisnt Star Mira
		Mira (officially called Omicron Ceti in the constellation Cetus) is the prototype for an entire class of stars known as "Mira-type variables." Although once like our Sun, Mira is now at the end of its life, and has evolved into a cool red giant star that is highly variable in brightness.
		Mira's companion is a burned-out star called a white dwarf that is surrounded by material captured from Mira's wind.
		Mira was discovered on August 13, 1596, by Dutch astronomer David Fabricus, who mistook it for a nova because it later faded from view.
	www.gsfc.nasa.gov /news-release/releases/1997/97-108.htm (549 words)

	Research Opportunities for SSUO
		For the geometric variables such as eclipsing binaries, these objects are variable, primarily, because of their special orientation in space with respect to the earth.
		Mira variables are likely losing mass with each pulsational cycle and many are known to be producing dust shells.
		Additional discoveries of Mira variables (LPVs) in the anti-center region may also be productive since it is known that the Miras in the outer regions of the galaxy have a different period distribution.
	www.phys-astro.sonoma.edu /observatory/research/research_opps.html (3456 words)

	D.U. Experience
		Variable stars are different from other types of stars in that they experience a phenonmena causing a change of flux (AAVSO, 1997).
		Pulsating variables vary due to regular or semi-regular pulsations of the outer shells of material of the star.
		In the case of Mira variables, oxygen is the main element produced (C/0 =.6).
	www.fiu.edu /~howarde/du.html (1237 words)

	Ceti
		Mira is a binary system with separation about 70 times more than that between Earth and the Sun, (equal to an angular size of only 0.6 arcseconds -- the apparent diameter of a dime at four miles away).
		Hubble resolves a small hook-like appendage extending from Mira, in the direction of the companion that could be material from Mira being gravitationally drawn toward the smaller star.
		Mira's companion is a white dwarf that is surrounded by material captured from Mira's wind.
	hyperphysics.phy-astr.gsu.edu /hbase/Starlog/ceti.html (779 words)

	The Pulsation Modes of Mira Variables
		Therefore, the suggestion is that the Mira variables are fundamental-mode pulsators while the second, shorter-period sequence of LPVs in Figure 5.1 consists of first-overtone pulsators.
		To test if the observations are consistent with fundamental-mode pulsation in the Mira variables, it is assumed that the model fundamental-mode periods corresponded to the observed Mira periods.
		If the Miras in the LMC are assumed to be pulsating in the fundamental mode, then the second sequence of LPVs corresponds well with pulsation in the first or second overtone.
	www.mso.anu.edu.au /~kim/thesis/node8.html (3311 words)

	Infrared Variability of Mira Stars
		A Mira variable is a star whose brightness varies by at least a factor of 10 (i.e., a magnitude change of at least 2.5), with a period of between 100 and 1000 days.
		Mira variables are often surrounded by shells of dust.
		To investigate how this dusty circumstellar shell varies with changes in the photosphere of the star, it is important to observe variations in the infrared brightnesses of the star, and compare with changes in visible light.
	www.etsu.edu /physics/bsmith/variable/COBE_mira.html (843 words)

	Variable Stars
		The star varies over a period of just under a year (the missing part of the brightness curves are the times of the year when the star is not seen at night.) The lower brightness curve is for Delta Cepheus, the flagship star of the Cepheid variables.
		Cepheid variables have a much shorter period than Mira variables, but 90% of them have the lightning signature of a fast rise and slow decay.
		Polaris is a binary Cepheid variable whose brightness has increased over the course of the last century, while the level of variability has decreased and the length of time over which it varies has became longer.
	www.thunderbolts.info /tpod/2005/arch05/050527variablexray.htm (664 words)

	Mira, Omicron Ceti
		Mira was the second variable and the first pulsating one to be discovered, on August 13, 1596 by David Fabricius (1564-1617), a disciple of Tycho Brahe and amateur astronomer, and then regarded as a nova because it appeared and faded from view later.
		Mira is the brightest and most famous long-period pulsating variable in the sky, and gave the name to this whole class of stars.
		Mira is also the dominant component of a double star, which is separated by only 0.6 arc seconds.
	www.seds.org /~spider/spider/Vars/mira.html (668 words)

	Conclusion
		Various possibilities for future work are outlined in Section 6.5.
		Twenty Long-Period Variables and nine other variables were identified, including two eclipsing variables (one newly discovered), and four close binary stars, two of which show emission lines in their spectra.
		Of the two variables (both Cepheids) located near the cluster core, one is a likely cluster member and the other is a probable field star.
	msowww.anu.edu.au /~kim/thesis/node9.html (1578 words)

	Mira: The Wonderful Star « Space Photos
		To seventeenth century astronomers, Omicron Ceti or Mira was known as a wonderful star - a star whose brightness could change dramatically in the course of about 11 months.
		Only 420 light-years away, red giant Mira (Mira A, right) itself co-orbits with a companion star, a small white dwarf (Mira B).
		Mira B is surrounded by a disk of material drawn from the pulsating giant and in such a double star system, the white dwarf star’s hot accretion disk is expected to produce some x-rays.
	jtintle.wordpress.com /2006/07/22/mira-the-wonderful-star (193 words)

	The New Jersey Astronomical Association (Site not responding. Last check: )
		The dwarf nova star is a cataclysmic variable composed of two stars of varied mass and size in close orbit.
		The Mira type variable appears to be in contrast with dwarf nova when considering that the amplitude of a Mira changes by 4 or more magnitudes usually in the course of 200-400 days.
		Mira's are typically large red giant stars that are reaching old age.
	www.njaa.org /research/variable02.html (499 words)

	Atlas Of The Light Curves (Site not responding. Last check: )
		This phaenomenon induce large variations of the magnitude, especially in the LPVs of the later spectral types, and favours the discovery of the redder and cooler variables of this type.
		The first was to estimate the increasing of the variable stars observed in the photographic infrared in comparison with a similar survey obtained with blue plates.
		For all variables with incert variability type and to find or to improve the periods of all LPVs, spectral analysis of the light curve was performed with a computer program, reported by Press and Rybicki (1989), implementing the method developed by Scargle (1982).
	astro.fisica.unipg.it /atlasmaffei/main.htm (1258 words)

	Mira Ceti
		Although the giant star Mira has been known for about 400 years, astronomers have had to wait for NASA's Hubble Space Telescope to provide the first ultraviolet images of the extended atmosphere of the cool red giant star and its nearby hot companion.
		In the lower two panels the reconstructed images of Mira are magnified and the companion is out of the field of view to the left from Mira.
		In UV light, Hubble resolves a small hook-like appendage extending from Mira, in the direction of the companion that could be material from Mira being gravitationally drawn toward the smaller star.
	www.xs4all.nl /~carlkop/mirahu.html (832 words)

	Miras (Site not responding. Last check: )
		Mira variables are red giant stars that have grown to enormous sizes after they finished "burning up" all the hydrogen in their outer atmosphere.
		For Miras when this happens, the visual light can be almost completely absorbed at large radii, extending the visual photosphere to nearly twice its nominal size.
		The figure to the left is a schematic depiction of the change in visual appearance of a Mira variable star at maximum (left-hand panel) and minimum (right-hand panel) light.
	www.cfa.harvard.edu /~reid/miras.html (504 words)

	Las estrellas variables
		Mira es una estrella variable clasificada como pulsante (no debe confundirse una estrella variable pulsante con un pulsar) y aún hoy su variación se repite regularmente con un período de alrededor de un año.
		Existen estrellas similares a Mira, que aumentan y disminuyen regularmente de tamaño, lo que involucra un cambio en la cantidad de luz que irradian al espacio.
		Algunas variables pulsantes son extremadamente brillantes y además tienen la particularidad de que el período de variación se relaciona directamente con el brillo intrínseco de la estrella (por brillo intrínseco se entiende el brillo que realmente tiene la estrella y no el brillo observado, que es el que se mide desde la Tierra).
	www.astronomiamoderna.com.ar /Lasestrellasvariables.html (549 words)

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