Mira

Mira is a very big, red star.

It is a special kind of star. It changes how bright it looks. It grows and shrinks in size.

This happens because the star pulses. The star is also very old. It is about six billion years old. It has a small friend nearby. This friend is a tiny, white star. Together, they move through space. Mira leaves a long trail behind it.

This trail is very long. It is made of gas and dust.

Mira is a special star in the Cetus constellation.

It is a red giant, which is a very large and old star. Mira is about six billion years old. It is a variable star. This means its brightness changes over time.

The star pulses, or grows and shrinks, in a regular way. This pulsing makes it look brighter and dimmer. Scientists say it takes about 332 days for one cycle.

Mira is part of a binary system. This means it has a partner star. Its partner is a white dwarf. A white dwarf is a small, hot, and dense star.

The two stars are close enough to share matter. A bridge of gas connects them.

Mira also moves through space at a very high speed. It leaves a long trail of gas behind it. This tail is 13 light-years long. The tail holds carbon and oxygen. These parts are needed to make new planets and life.

Mira is a very special star located in the Cetus constellation.

It is a red giant, which is a huge and old type of star. This star is part of a binary system, meaning it has a partner. The main star, called Mira A, is a pulsating variable star. This means it changes in brightness as it pulses. Its partner, called Mira B, is a small and hot white dwarf. This pair is a symbiotic system because the stars interact with each other.

The way Mira works is quite amazing to watch. Mira A undergoes a thing that happens called pulsing. This causes the star to expand and contract. As it pulses, the star changes its temperature and brightness. It is also losing mass, which is the star's outer material. This material travels along a bridge of gas toward the white dwarf. This process is a direct exchange of matter between the two stars. The white dwarf is actually gathering this material for itself.

People have been studying Mira for a very long time. An astronomer named David Fabricius recorded its changes in 1596. He first thought he was looking at the planet Mercury. Later, Johannes Holwarda found that the star's cycle lasts about eleven months. In 1662, Johannes Hevelius named the star Mira. This name means "wonderful" or "astonishing" in Latin. He chose this because the star acted like no other star he knew.

There are many interesting facts about this star system. Mira A is about six billion years old. It is one of the coolest bright red giant stars. Its temperature stays between 3,000 and 4,000 degrees Fahrenheit. The two stars are separated by about 70 astronomical units. Mira A is also very large. In 1925, Francis G. Pease measured its diameter at 250 to 260 million miles. This made it the second largest star known at that time.

Mira helps us understand how stars change over time. As Mira moves through space, it leaves a long tail. This tail is 13 light-years long and made of gas. It was formed over tens of thousands of years. This tail drops off important things like carbon and oxygen. These elements are needed to make new stars and planets.

By studying this tail, we learn how stars like our Sun might one day die.

Mira is a remarkable binary star system located in the constellation Cetus.

It is famous for being the prototype of Mira variables, a class of stars that change in brightness. The system is actually made of two different stars working together. The primary star, Mira A, is a massive red giant. Its companion, Mira B, is a small and hot white dwarf. Because these two stars interact closely, scientists call this a symbiotic system. This is the closest symbiotic pair to our own Sun.

The main star, Mira A, is currently in a stage called the asymptotic giant branch. This means it is a highly evolved star that is undergoing a thermally pulsing phase. During these pulses, which can last a decade or more, the star's luminosity increases. These cycles happen roughly every 10,000 years. These pulses create dynamic instability within the star. This instability leads to dramatic changes in the star's size and brightness over shorter, irregular periods.

Mira's variability is driven by its physical pulsations. The star's surface expands and contracts, which changes its temperature and brightness. As the star pulses, its radius can vary by over 20 percent. The temperature also shifts, though by less than 10 percent. Interestingly, the highest luminosity occurs when the star is at its hottest and smallest. The star's brightness can swing wildly. Its visual magnitude can reach as high as 2.0 or drop as low as 4.9. This represents a brightness range of almost 15 times.

Humans have been observing Mira's strange behavior for centuries. In 1596, the astronomer David Fabricius began recording its changes. He originally thought he was observing the planet Mercury. By 1638, Johannes Holwarda determined the star reappeared every eleven months. In 1662, Johannes Hevelius gave the star its name. He chose the Latin word Mira, meaning "wonderful" or "astonishing." He felt the star acted like no other object in the sky.

There are many impressive numbers associated with this star. Mira A is estimated to be about six billion years old. It is one of the coolest bright red giants, with temperatures between 3,000 and 4,000 degrees Fahrenheit. In 1925, Francis G. Pease measured its diameter using interferometry. He found it was between 250 and 260 million miles wide. At that time, it was the second largest star known to science. The two stars in the system are currently separated by about 70 astronomical units.

The interaction between the two stars is a constant process of mass exchange. Mira A is undergoing significant mass loss. Its gaseous material is very thin, about one-thousandth as dense as the air on Earth. This material travels along a bridge of matter toward the companion star. The Chandra X-ray Observatory has shown this direct exchange. Mira B, the white dwarf, is accreting this mass from the primary star. This transfer of material is a key feature of their symbiotic relationship.

As Mira moves through space, it leaves a massive trail behind it. The star travels at a high speed of 22 kilometers per second. This motion creates a hot bow wave of compressed gas. This interaction results in a tail that is 13 light-years long. The tail has been forming from shed material over the last 30,000 years. This tail is a vital resource for the galaxy. It drops off carbon, oxygen, and other elements. These elements are the building blocks needed to form new stars, planets, and perhaps even life.