1. Introduction

Canis Minor, a constellation in the northern celestial hemisphere, is notable for its compact size and distinct stellar features. Latin for "Lesser Dog," Canis Minor is depicted in Greek mythology as one of the hunting dogs accompanying Orion, the legendary hunter. Characterized by its two brightest stars, Procyon and Gomeisa, Canis Minor occupies a modest area of the night sky but holds significance for both astronomers and stargazers alike.

The celestial coordinates of Canis Minor position it between approximately 7h 00m and 8h 40m of right ascension and between +5° and +15° of declination. This places the constellation in close proximity to other notable celestial landmarks, such as Gemini to the north and Canis Major to the southwest. With its location in the northern celestial hemisphere, Canis Minor is observable from a wide range of latitudes, making it a familiar sight to observers in both hemispheres.

Canis Minor is distinguished by its two brightest stars, Procyon (α Canis Minoris) and Gomeisa (β Canis Minoris). Procyon, the alpha star of the constellation, is a binary system composed of a main-sequence star and a white dwarf companion. It shines with a visual magnitude of approximately 0.34, making it one of the brightest stars in the night sky. Gomeisa, the beta star, is a blue-white main-sequence star with a visual magnitude of around 2.90. Together, these stars contribute to the distinctiveness of Canis Minor and make it easily recognizable to observers (Figure 1).

Figure 1. IAU chart of Canis Minor. Source: https://www.iau.org/static/archives/images/screen/cmi.jpg. Credit: IAU and Sky & Telescope. Reproduced under CC BY 4.0 license.

2. Historical Background and Mythology

Canis Minor, although modest in size, possesses a rich historical background and mythology that dates back to ancient times. In Greek mythology, the constellation is closely associated with the legendary hunter Orion and his faithful hunting dogs. Canis Minor represents one of these loyal companions, typically depicted as a small dog following closely behind Orion in the night sky.

The most prevalent mythological narrative involving Canis Minor is its connection to the larger constellation of Orion. According to Greek mythology, Orion was a great hunter known for his extraordinary skills and prowess. Accompanying him on his hunting expeditions were two faithful dogs, Canis Major and Canis Minor. These dogs were said to have been gifted to Orion by the gods, and they remained loyal companions by his side throughout his adventures.

The specific identity of the dog represented by Canis Minor varies in different mythological traditions. Some interpretations suggest that Canis Minor represents Maera, a small dog belonging to Icarius, a legendary Athenian who was taught the art of winemaking by the god Dionysus. Maera was fiercely loyal to Icarius and was transformed into a constellation by the gods after his death as a reward for his devotion.

In ancient Egyptian mythology, Canis Minor is often associated with the god Anubis, who was depicted with the head of a jackal or dog. Anubis played a significant role in Egyptian funerary rituals as the god of mummification and the afterlife. Canis Minor may have been perceived as a celestial representation of Anubis, serving as a guide and protector of souls in the journey to the afterlife.

3. Notable Stars

3.1. Procyon (α Canis Minoris)

Procyon, designated as α Canis Minoris, holds a prominent place in the night sky as the brightest star in the constellation Canis Minor and one of the brightest stars visible from Earth. Its name is derived from the Greek word "Prokyon," meaning "before the dog," as it rises just before Sirius, the Dog Star in the neighboring constellation Canis Major. Procyon's significance extends beyond its brightness, as it is a fascinating binary star system with unique characteristics.

The Procyon system consists of two stars: Procyon A and Procyon B. Procyon A is the primary component, classified as a type F5IV-V main-sequence star. With a visual magnitude of approximately 0.34, Procyon A shines brightly in the night sky, captivating observers with its radiant glow. It has a mass about 1.4 times that of the Sun and a surface temperature of around 6,530 Kelvin. Procyon A is relatively close to Earth, located approximately 11.4 light-years away. Procyon B, the companion star, is a white dwarf and the closest known white dwarf to Earth. It orbits closely around Procyon A, completing one orbit approximately every 40 years. Procyon B is much fainter than Procyon A, with a visual magnitude of approximately 10.7. Despite its faintness, Procyon B is an intriguing object for astronomers, as it provides valuable insights into the later stages of stellar evolution. Its presence also played a significant role in verifying Albert Einstein's theory of general relativity, as its gravitational influence on Procyon A causes subtle shifts in the latter's position over time.

3.2. Gomeisa (β Canis Minoris)

Gomeisa is the second-brightest star in Canis Minor. It is a blue-white main-sequence star located approximately 170 light-years away from Earth. Gomeisa has a visual magnitude of around 2.90, making it considerably fainter than Procyon. Its name is derived from the Arabic phrase meaning "the bleary-eyed one," possibly referring to the star's appearance or its association with a mythical dog.

3.3. Luyten's Star

Luyten's Star, or GJ273, is a red dwarf star located in the constellation Canis Minor. Named after the Dutch-American astronomer Willem Jacob Luyten, who discovered its high proper motion in 1935, Luyten's Star holds particular interest due to its proximity to the Solar System and its status as one of the nearest known stars. Luyten's Star is classified as a type M3.5V dwarf, indicating that it is a relatively cool and dim main-sequence star. With a visual magnitude of approximately 9.9, Luyten's Star is too faint to be seen with the naked eye but can be observed with binoculars or a small telescope. It is located at a distance of about 12.36 light-years from Earth, making it one of the closest known stars to the Solar System.

One of the most notable characteristics of Luyten's Star is its high proper motion, which refers to its apparent motion across the sky relative to more distant stars. This rapid motion suggests that Luyten's Star is relatively close to the Sun and has a high velocity relative to the Solar System. In fact, Luyten's Star has one of the highest known proper motions of any star.