Vega Star in Lyra

stars Aug 13, 2022

Vega is one of the easiest stars to find in the night sky and can often be identified in areas of heavy light pollution. Vega is part of the constellation known as Lyra the Harp and it is an important star to astronomers both in the past and in the present. It was once the pole star In 12,000 BCE, and it will be again in 13,727 due to Earth's precession of the poles. It is identified as an A0 star and its distance is 25 light years away from our own solar system. 

Characteristics of Vega

Vega is the fifth brightest star in the night sky, which makes it very easy to find, even in areas with heavy light pollution. Vega has been used as the standard for magnitude for astronomers for many years, and it still is. When scientists classify stars, they use a color-magnitude scale called the Hertzsprung Russell diagram, or the HR diagram. It shows us a comparison of star color, temperature, and brightness. The Spitzer Space Telescope also discovered that Vega displays infrared excess.  It is also a variable star, which means its brightness changes over time. Vega is identified as a 10,000-degree Kelvin black body, however, its temperature actually varies. It has a different temperature at its pole than at its equator because it rotates rapidly, completing one spin every 12.5 hours. 

A comparison of Vega and the Sun.  Notice the differences in size and shape. Photo credit: By Matúš Motlo - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=112665109 

Vega is the standard for the magnitude system which astronomers use to classify how bright stars are in the sky. Vega’s magnitude is classified as 0, while our Sun has a magnitude of -25. The magnitude scale is an inverse one; the lower the magnitude number, the brighter the star. The sun has a much lower number because the Sun is so much closer to Earth. Vega is dimmer in the sky than our own Sun because it's much farther away at 25 light-years. But if both stars were placed next to each other, Vega would be much bigger and brighter than the Sun. 

Similarities and Differences between Vega and the Sun

Vega has many similarities and differences from our own Sun. In terms of mass and radius, Vega is bigger than our sun. It's estimated to be 2.1 times the mass of our sun. Vega is hotter than our sun and 40 times more luminous. Vega is not as spherical as our own sun. It bulges at the equator and is flattened at the poles because of its rapid rotation of 12.5 hours. Both our Sun and Vega rotate differently at the equator than at the poles because they are made of gas. They both contain a dust disk. Vega’s dust disk is similar to our own Kuiper Belt.

Comparison of the Vega System and our own Solar System.  Both are surrounded by disks of dust, but the sizes are different. Photo Credit: By NASA/JPL-Caltech http://www.nasa.gov/mission_pages/spitzer/multimedia/pia16611.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=24187596

Importance of Vega to Astronomers

Vega is one of the most studied stars by modern astronomers. Vega was the first star to be photographed (other than our sun) in 1850. Vega was the first spectrographic image that was produced (after our sun). It was one of the first stars in which its distance was measured using the parallax equation. It's also used as a baseline for calibrating the brightness of other stars. Vega has dust in its system, so astronomers continue to use it for comparison to other star systems.

How to Find Vega

Vega is located in the constellation of Lyra. Vega is fairly easy to find in the sky. It can be seen in both the northern and southern hemispheres. Vega passes right overhead or near the zenith in the northern hemisphere during the summer months. This makes it a very straightforward target to find. In the southern hemisphere, you need to look towards the northern horizon, which will be low above that horizon during the winter months. The best way to find Vega is through the Summer Triangle asterism. The Summer Triangle asterism is made up of three stars: Deneb, Altair, and Vega. Vega is the brightest of these three stars.

Legends of Lyra and Vega

Lyra is an ancient constellation, and its origins date back to the earliest human civilizations and that is because of Vega. It's a very bright star and stands out in the sky. Vega has many different representations throughout human history, but some of the earliest ancient middle eastern cultures identified Lyra as a vulture. Mythologies of the stars vary according to time, place, and culture. There is no one true mythology for any constellation or star, just a variety of them. 

The earliest incarnation of Lyra dates back to ancient middle eastern cultures in Mesopotamia, and then the ancient Greeks later identified this constellation as a harp. While a harp may not seem like an exciting object to be represented in the sky, the legend behind the constellation of Lyra is one of both love and tragedy. It's about the famous story between the lovers named Orpheus and Eurydice. Orpheus was a legendary musician and poet in greek mythology, and he could charm all animals, gods, and humans with his mystical harp. On the day that Orpheus and Eurydice were to be wed, he played his lyre for his new wife, and as she was dancing, she fell into a nest of vipers. There are many versions of this story; some say she was chased by a satyr, causing her to fall, but either way, she perished. When she stepped on the serpent, it bit her heel and she died instantly. Orpheus found her body and he was devastated by this loss, so he expressed his sorrow through his song. As he played his lyre, the gods and the nymphs were so moved that they encouraged him to travel to the underworld to retrieve his beloved. So Orpheus enchanted Hades and Persephone with his sorrowful music, and Hades allowed him to lead Eurydice out of the underworld, but there was a catch. Orpheus had to agree not to look at her until they both passed into the upper world. He agrees and guides her through the underworld, but at the end of his journey, Orpheus began to doubt if she was there.

Orpheus guides Eurydice out of the Underworld. There are many variations of this Greek legend.

So just as they reached the threshold, Orpheus turned to look at his wife before she stepped into the sun, and she disappeared forever. She went back into the underworld, and he lost his love for a second time. Orpheus never really overcame his grief, and he was later murdered by a band of maidens that were followers of the god Dionysus. Orpheus refused to pay homage to these maidens, and they took his life. So in death, Orpheus was reunited with Eurydice in the underworld. Zeus was moved by the tragedy and placed the harp of Orpheus up in the sky to honor the love between the doomed couple. 

There is a famous Chinese folk tale about Zhinü and Niulang. This couple was known as the Weaving Girl and the Cowherd. Vega represents the Weaving Girl (Zhinü), and Altair represents the Cowherd (Niulang). In this folktale, Zhinu and Niulang were two lovers who fell deeply in love, but in the process they abandoned their duties.  They were put on opposite sides of the celestial river, which is represented as the Milky Way. The legend states that on the seventh day of the seventh lunar month, magpies will spread their wings together to form a bridge for the lovers to unite. The two stars on the side of Altair also represent their sons. 

Vega (top bright star) and Altair (bottom bright star) are separated by the Milky Way Galaxy, which the ancients interpreted as a river of celestial light.  The two stars above and below Altair represent the sons of the two lovers. 

There's a very similar Japanese legend connected to Vega and Altair and it is the tale of Orihime and Hikoboshi. Princess Orihime was a seamstress who wove beautiful clothes by the heavenly river. Orihime worked hard on her weaving, but she became sad and despaired of ever finding love, so her father, god of the heavens, loved her dearly and arranged for her to meet Hikoboshi, the Cowherd. He lived on the other side of the Milky Way. The two fell in love and married. Their passion and devotion to each other were so deep that Orihime stopped weaving, and Hikoboshi allowed his cows to wander the heavens. Orihime’s father became angry and forbade the lovers to be together. They tried to reunite, but the celestial river was difficult to cross. But Orihime’s father loved his daughter, so he allowed the two lovers to meet once a year on the seventh day of the seventh month. In Japan, this folktale is celebrated during the Tanabata festival, where wishes are written on colored paper and hung on bamboo trees.

Vega is a beautiful star that is our close celestial neighbor.  It is a significant star to both present-day astronomers and ancient stargazers. The legends of this star are of both love and tragedy, and it is often the stories of the stars that we can connect to and help us remember the patterns of the stars. 

 

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