Interesting Facts About the Star Procyon
- Procyon is called Alpha Canis Minoris in the Bayer designation. It is a binary star system made up of Procyon A and Procyon B.
- Procyon A is the main component in the Procyon star system. It is an F-type main-sequence star with an apparent magnitude of 0.34. It is about 1.5 times as massive as the Sun and roughly twice as big.
- The smaller companion, Procyon B, is a white dwarf. This stellar remnant is much fainter and only has an apparent magnitude of 10.7.
- Procyon A and B orbit each other every 40 years. They are separated by about 15 astronomical units (AU) on average or 15 times the Sun-Earth distance. However, because they follow an elliptical orbit, they can be as close as 8.9 AU or as far as 21 AU.
- Procyon is the brightest star in Canis Minor constellation and a big part of this is because of its relatively close distance to us.
- Procyon and Gomeisa are the only stars in the constellation Canis Minor that are brighter than the fourth magnitude. As such, they are the only stars that make up the simple sky pattern of the celestial Lesser Dog.
- The Procyon star system is located 11.46 light-years or 3.51 parsecs from the solar system. It is one of the closest stars to us.
- From the perspective of the Procyon star system, the Sun would appear as a yellowish star with an apparent magnitude of 2.55. Our solar system would be located in the constellation of Aquila the eagle.
- Procyon forms the Winter Triangle asterism with two other famous stars—Sirius and Betelgeuse. These two are the first and tenth brightest stars in the night sky, respectively.
- Procyon is also part of the bigger Winter Hexagon asterism, with Rigel, Aldebaran, Capella, Pollux, and Sirius.
The Procyon Star (α Canis Minoris)
- Color: White (F-type)
- Spectral type: F5 IV–V / DQZ
- Apparent magnitude: 0.34 / 10.7
- Absolute magnitude: 2.66 / 13.0
- Mass: 1.50 solar masses / 0.6 solar masses
- Radius: 2 solar radii / 0.01
- Luminosity: 6.93 Suns / 0.00049 Suns
- Surface Temperature: 6,530 K / 7,740 K
- Constellation: Canis Minor
- Distance: 11.46 light-years/ 3.51 parsecs from the solar system
Procyon is the brightest point in the small constellation of Canis Minor. In fact, it is the only first-magnitude star in this faint constellation. Observations of this star in the past helped in discovering proper motion, which means that stars move and are not fixed in the sky.
Procyon AB is made up of an F-type star and a white dwarf star. The main component, Procyon A, is already in the late stage of the main-sequence phase. It is likely that this star has nearly converted all its hydrogen in the core into helium and is now transitioning into a subgiant. The companion star in the system is a white dwarf just like Sirius B. Procyon B, however, is much less massive and less luminous.
Procyon A and B orbit each other around a common barycenter with an orbital period of 40.84 years. Their orbit has an eccentricity greater than that of Mercury, and the two have an average separation of 15 AU. In the solar system, this is around the distance between the orbits of Saturn (9.5 AU) and Uranus (19.8 AU) from the Sun.
A Close Neighbor
Procyon is one of our closest stellar neighbors. It lies only 11.46 light-years from us as determined by the Hipparcos satellite of the European Space Agency (ESA).
Procyon looks prominent as seen from Earth because it is relatively close to us. However, the second-brightest star in the constellation, Gomeisa, is much brighter. While Procyon A has about seven solar luminosities, Gomeisa shines with the luminosity of 250 Suns!
Procyon can be observed as a white star with a faint yellow tinge. It is one of the easiest stars to identify with the unaided eye. Because of this, it is one of the 58 stars that are considered important in celestial navigation.
Procyon A is a naked-eye star with a visual magnitude of 0.34 and a spectral type of F5IV–V. The “IV–V” luminosity class indicates that this main-sequence star is on its way to evolving into a subgiant star.
Procyon A has 1.50 times the Sun’s mass but it is twice as large. Main-sequence stars with less than eight times the solar mass will evolve into red giants in the later stage of their life, the Sun included. By this time, Procyon A would expand to about 80–150 times its diameter now.
The effective temperature of this star is estimated to be around 6,530 K. To compare, the Sun’s temperature is around 5,778 K. Procyon A is more luminous than the Sun too because it is larger. It shines with the luminosity of about seven Suns combined.
Procyon B is the white dwarf companion in the Procyon star system.
To review, a white dwarf is a remnant of a dying star with an average mass like the Sun. At the endpoint of their lives, stars like this swell and expel their other layers which creates a beautiful planetary nebula. When the outer layer is expelled, what remains is a white dwarf—a very hot and dense core of the former star.
Procyon B has a spectral class of DQZ. It is very faint, with an apparent magnitude of only 10.7, way past the naked-eye limiting magnitude which is around 6.5 apparent magnitude.
This white dwarf star only has 0.6 times the solar mass and 0.01 of the Sun’s radius. Because it is a relatively small object, it also has very low luminosity (0.00049 Suns).
The parent star of Procyon B was likely about three times as massive as the Sun. This progenitor star came at the end of its stellar life around 1.19 billion years ago.
As a white-hot core of a dying star, Procyon B has a surface temperature of 7,740 K which is hotter than Procyon A. However, it is no longer generating energy and is only shining through residual heat. It will continue to cool over time until it no longer emits heat or light. By this time, it will become a black dwarf.
White dwarfs take a very long time to cool off. In fact, no white dwarf has completely cooled yet, so black dwarfs are still considered “theoretical.”
What’s in a Name?
Canis Minor is almost always associated with Canis Major, the Greater Dog. These two dog constellations have been long recognized together by ancient Babylonians and Egyptians.
The name Procyon is from the Greek word Prokyon which means “before the dog.” This is what the ancient Greeks used to describe this star as it rises above the horizon into the sky before Sirius the Dog Star does.
Procyon is called Nangar in Babylonian mythology. The Chinese name of this star is Nán Hé sān which means “the Third Star of South River.” South River itself is a Chines asterism that Procyon forms with Gomeisa and Epsilon Canis Minoris. In Greek mythology, this star is associated with the hound Maera.
Other less-known names are Antecanis, Elgomaisa, and Al Shira.
Canis Minor Constellation
Canis Minor is a small constellation with an area of only 183 square degrees. In terms of size, it ranks 71st among the 88 modern constellations of today. It is called the “lesser dog” in comparison to the bigger constellation of Canis Major, the “greater dog.”
The sky pattern of Canis Minor is very simple. It can be formed just by drawing an imaginary line to connect its two brightest stars, Procyon and Gomeisa. Other than that, the constellation has no other star brighter than the fourth magnitude. The form of Canis Minor can be interpreted as a little dog at the back of the constellation Monoceros the Unicorn.
The first-magnitude star, Procyon, is followed by the variable star Gomeisa which has an apparent magnitude of 2.84–2.92. Another notable star in the constellation is the red dwarf called Luyten’s Star. This red dwarf has an apparent magnitude of 9.87 and is located close to us at only 12.36 light-years. Some of the stars in the constellation have planets too!
Canis Minor has a few notable deep-sky objects. A great example is the planetary nebula Abell 24. The lenticular galaxy NGC 2508 and the interacting galaxies of NGC 2402 are in this constellation too. The 11 Canis-Minorids meteor shower seems to radiate in the sky region of Canis Minor.
The Lesser Dog was associated by ancient Egyptians with their god Anubis. The constellations of Canis Minor, Orion, and Gemini were important to the Aztecs because they formed an asterism which they called “Water.” It is said that the stars of these constellations guided the Aztecs on whether it was time to plant or harvest their crops.
In Greek mythology, Canis Minor is associated with the tale of the Teumessian Fox. In the story, the Teumessian Fox was a creature that never gets caught.
One day, the dog Laelaps, which always catches everything it hunts, was sent to get the fox. This resulted in a never-ending chase between the two! Ultimately, Zeus intervened and put them in the sky. The Teumessian Fox became Canis Minor and Laelaps became Canis Major.
In another story, it is said that Canis Minor is one of the two hunting dogs of Orion the Hunter.
The Winter Triangle Asterism
Aside from constellations, asterisms are other sky patterns that make our night sky more exciting. A great example of this is the Winter Triangle.
With an apparent magnitude of –1.46, Sirius is the brightest star in the night sky. The red star Betelgeuse, the second-brightest in Orion, is the tenth-brightest star overall. The apparent magnitude of this supergiant varies between +0.0 and +1.6. The third point in the asterism, Procyon, is a 0.34-magnitude star.
The name “Winter Triangle” pertains to the time this sky pattern can be best seen in the northern hemisphere. We can easily spot it in the months of December, January, and February. This time, however, it is summer in the southern hemisphere. The equilateral triangle looks upside down too in the southern sky.
The Winter Hexagon Asterism
The Winter Hexagon is also called the Winter Oval. It is made up of very bright stars and has the smaller Winter Triangle inside it. Two stars of the Winter Triangle, Procyon, and Sirius are also vertices of this larger asterism.
The stars that make up the Winter Hexagon are:
- Rigel – brightest star in Orion constellation; 7th brightest star
- Aldebaran – brightest star in Taurus constellation; 14th brightest star
- Capella – brightest star in Auriga constellation; 6th brightest star
- Pollux – brightest star in Gemini constellation; 17 brightest star
- Procyon – brightest star in Canis Minor constellation; 8th brightest star
- Sirius – brightest star in Canis Major constellation; the brightest overall
Where Can You See The Procyon Stars in the Night Sky?
The star Procyon is in the northern constellation of Canis Minor. This constellation is visible between 90° latitude in the northern hemisphere and 75° latitude in the southern hemisphere. Below are the coordinates of the star Procyon:
- Right ascension: 07h 39m 18s
- Declination: +05° 13′ 29″
Neighboring stars and constellations are also helpful in locating Procyon in the sky. The small constellation of Canis Major is surrounded by larger and more prominent constellations:
How and When to Find Procyon Star?
Procyon is prominent during the winter months of December, January, and February in the northern hemisphere.
While it is cold north of the equator, the southern hemisphere is experiencing summer in the same months. The star is at its highest point in the sky at around 9m pm and is best seen around late winter.
There are many ways to spot Procyon in the night sky. The easiest one is to use the Winter Triangle and the very bright stars nearby. The easiest one to find is Sirius, the brightest star in the sky. Betelgeuse is another easy object to spot because of its unmistakable reddish hue. After all, it is part of the conspicuous constellation of Orion.
Procyon is located left of the red supergiant Betelgeuse. You can draw an imaginary line to connect these three stars, forming the equilateral triangle that is the Winter Triangle.
Procyon Star in Mythology
The star Procyon is said to be Erigone’s dog named Maera.
Erigone’s father is Icarius. He was a follower of Dionysus so he was known for his great ability in winemaking. During one of his travels, Icarius offered his wine to some shepherds. Unluckily, the shepherds died so their other companions attacked and killed Icarius.
Back home, Erigone became worried about her father. She decided to look for him together with her dog Maera. Because of its strong senses, the dog was able to track Icarius’s grave under a tree.
Erigone became so heartbroken with what happened to her father. She was so depressed that she decided to end her life, and Maera jumped off a cliff too.
The god Dionysus saw what happened and felt sorry for the family. He was furious and brought plagues to Athens. The calamities only ended when the people offered rites for Icarius and Erigone.
Dionysus rewarded Erigone, Icarius, and Maera by putting them in the sky. Erigone became the Virgo constellation while Icarius became the constellation of Boötes. The hound, Maera, became the brightest star in Canis Minor, Procyon. The dog was placed near the celestial river (the Milky Way) so he would never get thirsty.
The Procyon Star (α Canis Minoris): Credits: Obtained from Hubble Legacy Archive and processed by Brandon Pimenta
Procyon A: By: Fernando Oliveira de Menezes (https://www.astrobin.com/328519/?q=procyon)
Canis Minor Constellation: https://upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Canis_Minor_IAU.svg/800px-Canis_Minor_IAU.svg.png
Abell 24: https://upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Red_and_Long_Dead_Abell_24.tif/lossy-page1-800px-Red_and_Long_Dead_Abell_24.tif.jpg
The Winter Triangle Asterism: https://upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Hubble_heic0206j.jpg/1024px-Hubble_heic0206j.jpg
The Winter Hexagon Asterism: https://upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Winter_Hexagon_and_Great_Southern_Triangle_%28Stellarium%29.png/1024px-Winter_Hexagon_and_Great_Southern_Triangle_%28Stellarium%29.png
Where Can You See Procyon in the Night Sky?: https://stellarium-web.org/
How and When to Find Procyon?:
Procyon in Mythology: https://upload.wikimedia.org/wikipedia/commons/9/9e/Cmi.jpg