The fixed stars move, some quite rapidly. In our Galaxy, many of the stars move together, orbiting around the center of the Milky Way in (more or less) unison. But some stars are more independent than others, and take the road less traveled by. The star Mira ("Wonderful", so named by the Polish astronomer Johannes Hevelius in 1662) is one of the more independent, a pulsating red giant binary with a white dwarf companion. Mass flows from the red giant to the white dwarf, and this entire systems hurtles through the Milky Way at nearly 300,000 miles per hour, relative to its surrounding material. This high relative speed produces a strong "bow shock" like a speedboat moving on a lake, and also a surprisingly long, narrow tail which stretches more than 13 lightyears, about three times the distance between the sun and its next nearest stellar neighbor. This tail, shown above, glows in ultraviolet light and was discovered by the the Galaxy Evolution Explorer (GALEX) during part of its UV survey of the entire sky.
<<Mira, designation Omicron Ceti (ο Ceti, abbreviated Omicron Cet, ο Cet), is a red-giant star estimated to be 200–400 light-years from the Sun in the constellation Cetus. ο Ceti is a binary stellar system, consisting of a variable red giant (Mira A) along with a white dwarf companion (Mira B). Mira A is a pulsating variable star and was the first non-supernova variable star discovered, with the possible exception of Algol. It is the prototype of the Mira variables.
Ultraviolet studies of Mira by NASA's Galaxy Evolution Explorer (GALEX) space telescope have revealed that it sheds a trail of material from the outer envelope, leaving a tail 13 light-years in length, formed over tens of thousands of years. It is thought that a hot bow wave of compressed plasma/gas is the cause of the tail; the bow wave is a result of the interaction of the stellar wind from Mira A with gas in interstellar space, through which Mira is moving at an extremely high speed of 130 kilometres per second . The tail consists of material stripped from the head of the bow wave, which is also visible in ultraviolet observations. Mira's bow shock will eventually evolve into a planetary nebula, the form of which will be considerably affected by the motion through the interstellar medium (ISM).>>
<<A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. The word is from the Latin neuter vīrus referring to poison and other noxious liquids, from the same Indo-European base as Sanskrit viṣa and ancient Greek ἰός (all meaning 'poison'), first attested in English in 1398 in John Trevisa's translation of Bartholomeus Anglicus's De Proprietatibus Rerum. Virulent, from Latin virulentus ('poisonous'), dates to c. 1400. A meaning of 'agent that causes infectious disease' is first recorded in 1728, long before the discovery of viruses by Dmitri Ivanovsky in 1892. The English plural is viruses (sometimes also vira), whereas the Latin word is a mass noun, which has no classically attested plural (vīra is used in Neo-Latin). The term virion (plural virions), which dates from 1959, is also used to refer to a single viral particle that is released from the cell and is capable of infecting other cells of the same type.>>
<<A runaway star, plowing through the depths of space and piling up interstellar material before it, can be seen in this ultraviolet image from NASA's Galaxy Evolution Explorer. The star, called CW Leonis, is hurtling through space at about 91 kilometers per second. It is shedding its own atmosphere to form a sooty shell of discarded material. This shell can be seen in the center of this image as a bright circular blob. CW Leonis is moving from right to left in this image. It is travelling so quickly through the surrounding material that it has formed a semi-circular bow shock in front of itself, like a boat moving through water. This bow shock is made of superheated gas, which flows around the star and is left behind in its turbulent wake. This blown-out bubble is 2.7 light-years across, which is more than half the distance from our sun to the nearest star, or 2,100 times the size of Pluto's orbit. The size of the bubble (called the "astrosheath") has allowed astronomers to estimate that CW Leonis has been shedding its atmosphere for about 70,000 years. This is part of the star's natural life cycle as it runs out of hydrogen fuel and gradually throws off its outer layers to expose its bare, dying core. This core is called a white dwarf, and is the end product of all low-mass stars like our sun. CW Leonis is the second runaway star to be observed with the Galaxy Evolution Explorer. The first, Mira, was observed by the telescope back in 2006. This image is the combination of near-ultraviolet data, shown in yellow, and far-ultraviolet data, shown in blue.>>