Out in the universe are zillions of stars and other objects though we see only a few thousands. Of those thousands, some are better known than others. Here are a handful of some of the well-known stars.
Aldebaran is the brightest star in the constellation Taurus (it is one of the bull’s eyes) and is the 13th brightest star in the sky.
picture courtesy : NASA
Aldebaran is a giant, old, orange star that is cooler than the Sun; it is under 4,000 Kelvin (the Sun is 5,800 Kelvin), located about 65 light years away.
Aldebaran means “the Follower” in Arabic (since it seems to follow the stars in the Pleiades.)
The star has moved off the main sequence line of the Hertzsprung–Russell diagram after exhausting the hydrogen at its core.
As a result of the increase in the core temperature, the star has expanded to a diameter of 44.2 times the diameter of the Sun.
Comparative size of Sun to Aldebaran
Alpha Centauri is the star system that is closest to the Earth about four light years. It is actually a multistar system, consisting of Alpha Centauri A, B, and Proxima Centauri (aka. Centauri C).
(The dimmest star in the system, Proxima Centauri (Alpha Centauri C), is the closest star to our sun). The stars Alpha Centauri A and Alpha Centauri B are close binary stars.
Based on their spectral classifications,
Alpha Centauri A is a main sequence white dwarf with roughly 110% of the mass and 151.9% the luminosity of our Sun.
Alpha Centauri B is an orange subgiant with 90.7% of the Sun’s mass and 44.5% of its luminosity.
Proxima Centauri, the smallest of the three, is a red dwarf roughly 0.12 times the mass of our Sun, and which is the closest of the three to our Solar System.
In 2012, astronomers discovered an Earth-sized planet around Alpha Centauri B. Known as Alpha Centauri Bb. Its close proximity to its parent star likely means that it is too hot to support life.
Antares (meaning “Rival of Mars”) a.k.a. Alpha Scorpii , is the brightest star in Scorpius, one of the constellations in the zodiac. Antares is a red supergiant star that is about 520-550 light-years from Earth and is about 850 times in diameter as the Sun.
picture courtesy: earthsky.org
This supergiant is estimated to be 17 times more massive, 10,000 times more luminous than our Sun. The most recent estimates place its age at 12 million years.
picture courtesy : space.com
(Alpha Boötis) Arcturus is the brightest star in the constellation Boötes (the herdsman). It is a red giant that is the fourth brightest star in the sky. Arcturus is 34 light-years from Earth.
(pronounced “beetle juice”) Betelgeuse (alpha Orionis) is the second-brightest star in the constellation Orion and one of the brightest stars in the sky. It is a supergiant star, reddish in color, and over 600 million miles in.
Betelgeuse is about 14,000 times brighter than the Sun.
Pictured by Hubble telescope
picture courtesy: spacetelescope.org
If Betelgeuse were at the center of our Solar System, it would extend beyond the orbit of Jupiter. It is 520-650 light-years from Earth.
It is the only star (other than our sun) for which we have surface images.
Betelgeuse will one day go supernova, which is sure to be a spectacular event that people on Earth will be able to see. However, the exact date of when that might happen remains unknown.
picture courtesy : earthsky.org
Also known as Alpha Carinae, this white giant is the brightest star in the southern constellation of Carina and the second brightest star in the nighttime sky. Located over 300 light-years away from Earth, this star is named after the mythological Canopus, the navigator for king Menelaus of Sparta in The Iliad.
Canopus photographed from International Space Station
picture courtesy: ISS
Though it was not visible to the ancient Greeks and Romans, the star was known to the ancient Egyptians, as well as the Navajo, Chinese and ancient Indo-Aryan people.
In Vedic literature, Canopus is associated with Agastya, a revered sage who is believed to have lived during the 6th or 7th century BCE.
To the Chinese, Canopus was known as the “Star of the Old Man”, and was charted by astronomer Yi Xing in 724 CE.
It was also used along with Polaris as the two principal stars for navigation at night.
This star is commonly used for spacecraft to orient themselves in space, since it is so bright compared to the stars surrounding it.
picture courtesy :earthsky.org
Deneb (which means “tail” in Arabic) is the brightest star in the constellation Cygnus (the swan); Deneb is also referred to as alpha Cygni, and is the tail of the swan. This young, bright, white supergiant star is perhaps 1,500 light years away. Deneb is about 60,000 times more luminous than the sun!
picture courtesy :earthsky.org
Polaris is the current pole star for the Northern Hemisphere; it is 1 degree from the exact Northern celestial pole.
It is the larger star at the end of the handle of the Little Dipper (Ursa Minor).
Also known as the North Star (as well as the Pole Star, Cynosure, Lodestar, and sometimes Guiding Star), Polaris is the 45th brightest star in the night sky
Its proximity to the north celestial pole, is why it has been used as a navigational tool in the northern hemisphere for centuries
Polaris’ distance from Earth has been estimated to be from 360 to 820 light years. At its brightest, Polaris is about 6,000 to 10,000 times brighter than our Sun.
Interestingly enough, Polaris wasn’t always the North Star. That’s because Earth’s axis wobbles over thousands of years and points in different directions. But until such time as Earth’s axis moves farther away from the “Polestar”, it remains our guide.
Also known as the “Seven Sisters”, Messier 45 or M45, Pleiades is actually an open star cluster located in the constellation of Taurus. At an average distance of 444 light years from our Sun, it is one of the nearest star clusters to Earth, and the most visible to the naked eye. Though the seven largest stars are the most apparent, the cluster actually consists of over 1,000 confirmed members (along with several unconfirmed binaries).
picture courtesy: wikipedia
The core radius of the cluster is about 8 light years across, while it measures some 43 light years at the outer edges. It is dominated by young, hot blue stars, though brown dwarfs – which are just a fraction of the Sun’s mass – are believed to account for 25% of its member stars.
The age of the cluster has been estimated at between 75 and 150 million years, and it is slowly moving in the direction of the “feet” of what is currently the constellation of Orion.
The cluster has had several meanings for many different cultures here on Earth, which include representations in Biblical, ancient Greek, Asian, and traditional Native American folklore.
Venus and the constellation Pleiades side-by-side
picture courtesy :esa.int
Rigel (beta Orionis) is the brightest star in the constellation and one of the brightest stars in the sky located between 700 and 900 light years away.
Though Rigel appears to be a blue supergiant, it is actually a multistar system.
picture courtesy : windows2universe.org
The primary star (Rigel A) is a blue-white supergiant that is 21 times more massive than our sun, and shines with approximately 120,000 times the luminosity. Rigel A is a young star, only 10 million years old. And given its size, it is expected to go supernova when it reaches the end of its life.
Rigel B is itself a binary system, consisting of two main sequence blue-white subdwarf stars.
Rigel B is more massive than Rigel C, weighing in at 2.5 solar masses versus Rigel C’s 1.9. Rigel has been recognized as being a binary since at least 1831 when German astronomer F.G.W. Struve first measured it.
Sirius (meaning “scorching” in Greek), also known as the Dog Star, is in the constellation Canis Major (The Great Dog).
Sirius is actually a binary star system, consisting of a white main-sequence star named Sirius A, and a faint white dwarf companion named Sirius B.
The reason why it is so bright in the sky is due to a combination of its luminosity and distance- it is one of Earth’s nearest neighbors. And in truth, it is actually getting closer. For the next 60,000 years or so, astronomers expect that it will continue to approach our Solar System and will begin to recede again.
In ancient Egypt, it was seen as a signal that the flooding of the Nile was close at hand. For the Greeks, the rising of Sirius in the night sky was a sign of the “dog days of summer”. To the Polynesians in the southern hemisphere, it marked the approach of winter and was an important star for navigation around the Pacific Ocean.
Vega (Alpha Lyrae) is a very bright star in the constellation Lyra. It is also known as the Harp Star and Fidis. Vega is the 5th brightest star in the sky and is pale blue. It is about 25 light years from Earth. Vega, together with Deneb and Altair form the Summer Triangle
Picture of Vega taken by Spitzer telescope
picture source : earthsky.org
Vega is roughly 2.1 times as massive as our Sun. Together with Arcturus and Sirius, it is one of the most luminous stars in the Sun’s neighborhood. It is a relatively close star at only 25 light-years from Earth.
Vega was the first star other than the Sun to be photographed and the first to have its spectrum recorded.
Based on observations that showed excess emission of infrared radiation, Vega is believed to have a circumstellar disk of dust. This dust is likely to be the result of collisions between objects in an orbiting debris disk. For this reason, stars that display an infrared excess because of circumstellar dust are termed “Vega-like stars”.
Thousands of years ago, (ca. 12,000 BCE) Vega was used as the North Star is today, and will be so again around the year 13,727 CE.
picture courtesy: skyandtelescope.com
Information sources: enchantedlearning.com, universetoday