A glowing, comet-like tail has been discovered trailing behind a double star called Mira, a phenomenon never seen before. It may contain clues about the star's activity over the past 30,000 years.Mira, which means "wonderful" in Latin, is one of the best-studied star systems in the sky and lies 350 light years from Earth. One star in the pair, called Mira A, is a bloated, ageing red giant that sheds large amounts of gas and dust into space, while the other, Mira B, is a dense stellar corpse called a white dwarf.
Previous studies had shown that some of the material from Mira A's wind has collected into a disc – which could potentially form planets – around Mira B (see Dying star's wind creates planetary nursery).
Now astronomers led by Christopher Martin of Caltech in Pasadena, US, have discovered the long tail, which is visible only in far ultraviolet light. They happened upon it using NASA's Galaxy Evolution Explorer (GALEX) satellite, which was surveying the sky at ultraviolet wavelengths.The tail extends 13 light years from Mira – if it were visible in the sky, it would span the width of four full Moons. It appears to trace the path of Mira's motion across the sky over the past 30,000 years, based on its size and Mira's speed, which has been previously measured.
Martin's team believes the tail is created as a result of Mira A's stellar wind – an outflow of gas and dust from the star – hitting ambient gas as it moves through space. Fast-moving electrons generated by the collision then strike hydrogen molecules in surrounding gas, producing ultraviolet light. This creates a glowing trail behind Mira as it travels through the galaxy at 130 kilometres per second. the tail could shed light on why some stars turn into white dwarfs and others explode as supernovae.stars such as Mira A, which start out with a few times the mass of the Sun, avoid this fate by shedding most of their mass in stellar winds to become placid white dwarfs
Previous studies had shown that some of the material from Mira A's wind has collected into a disc – which could potentially form planets – around Mira B (see Dying star's wind creates planetary nursery).
Now astronomers led by Christopher Martin of Caltech in Pasadena, US, have discovered the long tail, which is visible only in far ultraviolet light. They happened upon it using NASA's Galaxy Evolution Explorer (GALEX) satellite, which was surveying the sky at ultraviolet wavelengths.The tail extends 13 light years from Mira – if it were visible in the sky, it would span the width of four full Moons. It appears to trace the path of Mira's motion across the sky over the past 30,000 years, based on its size and Mira's speed, which has been previously measured.
Martin's team believes the tail is created as a result of Mira A's stellar wind – an outflow of gas and dust from the star – hitting ambient gas as it moves through space. Fast-moving electrons generated by the collision then strike hydrogen molecules in surrounding gas, producing ultraviolet light. This creates a glowing trail behind Mira as it travels through the galaxy at 130 kilometres per second. the tail could shed light on why some stars turn into white dwarfs and others explode as supernovae.stars such as Mira A, which start out with a few times the mass of the Sun, avoid this fate by shedding most of their mass in stellar winds to become placid white dwarfs
1 comment:
As usual, this is again an important and rare information. Keep us updating about the astro news.
--Ashutosh
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