Pollux (star)

Pollux is a very bright star.

It is part of a group called Gemini. This group is known as the twins.

This star looks orange in the sky. It is a giant star. It is much bigger than our Sun.

It is also much heavier than our Sun.

This star is quite close to us. It is the closest giant star to our Sun. A planet orbits this star. The planet is called Thestias.

Scientists use this star to study others. It is a very steady star. It helps us learn about space.

Pollux is a very bright star. It is the brightest star in the Gemini constellation.

Gemini is a group of stars known as the twins.

Pollux looks orange in the sky. This color comes from its temperature. It is a red giant star. This means it is a large, old star. It is much bigger than our Sun. It has about nine times the radius of the Sun. The radius is the distance from the center to the edge.

It also has about two times the mass of the Sun. Mass is how much matter is in something.

This star is very close to us. It is only 34 light-years away. It is the closest giant star to our Sun. Scientists use Pollux to study other stars. Its light is very steady.

This helps them group stars by their light.

A planet orbits this star. Its name is Thestias. This planet is an exoplanet. An exoplanet is a planet that orbits a star other than our Sun. Thestias is at least 2.3 times the mass of Jupiter. It takes about 590 days to orbit Pollux.

Pollux is a very bright star in the night sky. It is the brightest star in the constellation Gemini.

The name Pollux comes from Greek and Roman myths about twins. These twins were named Castor and Pollux. This star is a red giant, which is a type of large, old star. It has an orange color because of its temperature. This star is quite special to astronomers. Since 1943, scientists have used its light to help group other stars.

This star works in a way that changed over time. It used to be a smaller star like Sirius. It was once an A-type main-sequence star. Then, it used up the hydrogen at its core. This caused the star to grow into a giant. Now, it is a K0 III type star. This means it is a cooler, yellow-orange giant. It is much bigger than our Sun. It has about two times the mass of the Sun. It also has almost nine times the radius of the Sun.

Many people have studied this star throughout history. In old star catalogs, it had different names. One name was Muekher al Dzira. This was translated into Latin as Posterior Brachii. This means "the end in the paw." In China, it is part of a group called North River. In 1818, the poet Percy Shelley wrote about the star. He called it "mild Pollux." In 2016, a group called the WGSN helped organize star names. They officially approved the name Pollux for this star.

There are many interesting numbers to know about Pollux. It is located 34 light-years away from our Sun. This makes it the closest red giant to us. Its brightness is measured at 1.14. This makes it brighter than its neighbor, Castor. The star's temperature is about 4,600 Kelvin. Scientists also found a very weak magnetic field on its surface. This field is below 1 gauss. It is one of the weakest fields ever found on a star.

Pollux is also part of a planetary system. In 2006, scientists announced an exoplanet orbits this star. An exoplanet is a planet that orbits a different star. This planet is named Thestias. It was originally called Pollux b. Thestias is at least 2.3 times the mass of Jupiter. It takes about 590 days to complete one orbit.

The name Thestias came from a public voting process. It was chosen because Leda was the name of Pollux's mother. The name Thestias was used instead of Leda. This was because Leda was already a name for an asteroid. It is also a name for a moon of Jupiter.

Pollux is the brightest star in the constellation Gemini. It is classified as an evolved red giant star. This means it is an older star that has changed its shape and size. Astronomers call it a K0 III type star. It has a distinct orange hue. This color comes from its effective temperature of about 4,600 Kelvin.

Pollux is located approximately 34 light-years away from our Sun. This distance makes it the closest red giant to our solar system. It has a very high apparent visual magnitude of 1.14. This value makes it brighter than its neighbor, Castor. Because of its proximity, its apparent and absolute magnitudes are quite close. Since 1943, the spectrum of this star has helped classify other stars. It serves as a stable anchor point for astronomers.

The star has undergone a major physical transformation. It began its life as an A-type main-sequence star. This means it was once a hot, bluish-white star similar to Sirius. Eventually, the star exhausted the hydrogen fuel at its core. This loss of fuel caused the star to evolve into a giant. Today, it is much larger than the Sun. It has about two times the mass of the Sun. Its radius is almost nine times larger than the Sun's radius.

Measuring the size of Pollux has changed over time. In 1925, John Stanley Plaskett used interferometry to estimate its diameter. He calculated it was 13 million miles across. Modern measurements provide different figures. The Navy Precision Optical Interferometer measured a radius of 8.8 solar radii. Other studies use spectral lines to find its size. Scientists also study its metallicity, which is the abundance of elements other than hydrogen and helium. Estimates for its metallicity range from 85% to 155% of the Sun's level.

Pollux has many historical names from different cultures. In the Calendarium of al Achsasi al Mouakket, it was named Muekher al Dzira. This Latin translation means "Posterior Brachii," or "the end in the paw." In China, it is part of an asterism called North River. The name Pollux comes from Greek and Roman mythology. It refers to one of the twin brothers, Castor and Pollux. In 2016, the International Astronomical Union's Working Group on Star Names officially approved the name Pollux.

Recent discoveries have revealed a planetary system around the star. In 2006, scientists confirmed the existence of an exoplanet named Pollux b. This planet is now officially named Thestias. The name came from the NameExoWorlds process launched by the IAU in 2014. Thestias is the patronym of Leda, who was the mother of Pollux in myth. The name Leda was not used because it belongs to an asteroid and a moon of Jupiter. Thestias has a mass at least 2.3 times that of Jupiter. It completes one orbit around Pollux every 590 days.

Astronomers have also studied the magnetic activity of the star. The ROSAT orbiting telescope detected weak X-ray emissions from Pollux. These emissions are about 10^27 erg s^-1, which is similar to the Sun's X-ray output. A magnetic field below 1 gauss has been confirmed on its surface. This is one of the weakest magnetic fields ever detected on a star. This low level of activity suggests Pollux might have once been an Ap star. Such stars possess much stronger magnetic fields than what we see today.