1. Introduction

Canes Venatici, a constellation in the northern celestial hemisphere, is renowned for its rich astronomical offerings and historical significance. Latin for "hunting dogs," Canes Venatici is emblematic of the two dogs accompanying Boötes, the Herdsman, in Greek mythology. Positioned between Ursa Major and Boötes, this constellation boasts a diverse array of celestial wonders, captivating both seasoned astronomers and amateur stargazers alike.

Its celestial coordinates place Canes Venatici between 12h 20m and 14h 50m of right ascension and between +35° and +55° of declination. This positioning situates it in the vicinity of other notable constellations such as Ursa Major, Coma Berenices, and Boötes. With its prime location in the northern sky, Canes Venatici is visible to observers located in both hemispheres, making it a universally recognized and appreciated constellation.

Canes Venatici is distinguished by its modest size and lack of prominent stars. Its most notable feature is the pair of stars, Cor Caroli (α Canum Venaticorum) and Chara (β Canum Venaticorum), which represent the hunting dogs Asterion and Chara in Greek mythology. Despite its sparse stellar population, Canes Venatici is celebrated for hosting an abundance of deep-sky objects, including galaxies, star clusters, and nebulae.

One of the most famous objects within Canes Venatici is the Whirlpool Galaxy (M51), a stunning spiral galaxy located approximately 23 million light-years away. Additionally, M63 (the Sunflower Galaxy) and M94 are other prominent galaxies residing within this constellation. These celestial marvels make Canes Venatici a favored destination for astronomers seeking to explore distant galaxies and study the mysteries of the cosmos.

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

2. Historical Background and Mythology

The historical background and mythology surrounding the constellation Canes Venatici provide fascinating insights into the cultural significance of celestial observations throughout human history. Rooted in ancient Greek and Roman mythology, Canes Venatici has captured the imagination of civilizations for millennia, serving as a celestial canvas upon which stories of gods, heroes, and mythical creatures are painted.

In Greek mythology, Canes Venatici is closely associated with the figure of Boötes, the Herdsman, and his two faithful hunting dogs. According to legend, Boötes was a skilled hunter and herdsman who was rewarded by the gods for his unwavering loyalty and dedication. In recognition of his service, the goddess Hera placed Boötes, along with his dogs, into the heavens as a constellation for all eternity. The two dogs, Asterion and Chara, are represented by the stars Cor Caroli (α Canum Venaticorum) and Chara (β Canum Venaticorum), respectively, in the constellation Canes Venatici.

The origins of Canes Venatici as a distinct constellation date back to the 17th century when it was formally delineated and cataloged by the Polish astronomer Johannes Hevelius. Hevelius introduced Canes Venatici in his celestial atlas "Firmamentum Sobiescianum," published in 1690, alongside other newly defined constellations. Inspired by classical mythology and celestial observations, Hevelius sought to expand the catalog of recognized constellations, contributing to the rich tapestry of astronomical lore that persists to this day.

Throughout history, Canes Venatici has been referenced in various cultural and literary works, further cementing its significance in the human imagination. In William Shakespeare's play "Julius Caesar," the character of Cassius speaks of "the barking of the hounds" in reference to Canes Venatici, symbolizing impending danger and unrest. Similarly, the constellation has appeared in numerous works of art, literature, and music, reflecting its enduring influence on human creativity and expression.

In addition to its mythological and cultural significance, Canes Venatici holds historical importance in the development of astronomy and scientific inquiry. As one of the constellations cataloged during the Age of Enlightenment, Canes Venatici played a role in expanding humanity's understanding of the cosmos and our place within it. Astronomers such as Charles Messier and William Herschel observed and documented celestial objects within Canes Venatici, contributing to our knowledge of galaxies, star clusters, and nebulae.

3. Notable Stars 

Cor Caroli (α Canum Venaticorum): Cor Caroli, also known as Alpha Canum Venaticorum, is the brightest star in Canes Venatici and one of its most prominent features. Its name, which means "heart of Charles" in Latin, honors King Charles I of England. The star was named by Sir Charles Scarborough, physician to King Charles II, in the 17th century. Cor Caroli is a binary star system composed of two stars: Cor Caroli A, a white main-sequence star, and Cor Caroli B, a fainter companion star. These stars orbit each other with a period of about 5.47 days. Cor Caroli is approximately 110 light-years away from Earth and shines with a visual magnitude of about 2.81, making it easily visible to the naked eye.

Chara (β Canum Venaticorum): Chara, also designated Beta Canum Venaticorum, is the second-brightest star in Canes Venatici. Its name is derived from the Greek word for "joy" or "happiness," reflecting its historical significance as one of the hunting dogs accompanying Boötes, the Herdsman, in Greek mythology. Chara is a binary star system composed of a yellow-white main-sequence star and a fainter companion star. The primary star, Chara A, is similar in size and characteristics to the Sun and is located approximately 27 light-years away from Earth. Chara B, its companion, is much fainter and orbits Chara A with a period of about 169 years.

4. Deep-Sky Objects

Messier 51 (M51) - The Whirlpool Galaxy: Messier 51, commonly known as the Whirlpool Galaxy, is perhaps the most famous deep-sky object in Canes Venatici. Located approximately 23 million light-years away from Earth, M51 is a stunning spiral galaxy that interacts with a smaller companion galaxy, NGC 5195. The gravitational interaction between these galaxies has triggered intense star formation and created intricate structures of gas and dust. The Whirlpool Galaxy is a favorite target for amateur astronomers and astrophotographers due to its striking appearance and dynamic nature.

Messier 63 (M63) - The Sunflower Galaxy: Messier 63, also known as the Sunflower Galaxy, is another prominent spiral galaxy in Canes Venatici. It derives its name from the bright spiral arms that resemble the petals of a sunflower. M63 is located approximately 27 million light-years away from Earth and exhibits active star formation in its spiral arms, where young, hot stars illuminate surrounding clouds of gas and dust. The Sunflower Galaxy is a captivating sight in telescopes, with its intricate structure and bright nucleus.

Messier 94 (M94) - The Cat's Eye Galaxy: Messier 94, nicknamed the Cat's Eye Galaxy, is a striking spiral galaxy located approximately 16 million light-years away from Earth. It is characterized by a bright central core surrounded by a ring of intensely blue regions, where new stars are actively forming. M94's unusual appearance has led astronomers to classify it as a "starburst galaxy," indicating its high rate of star formation compared to other galaxies of similar size.

NGC 4631 - The Whale Galaxy: NGC 4631, also known as the Whale Galaxy, is an edge-on spiral galaxy located approximately 30 million light-years away from Earth. Its elongated shape and dark dust lanes give it the appearance of a whale swimming through space. NGC 4631 is accompanied by a number of satellite galaxies, including NGC 4627 and NGC 4656, which are thought to have been gravitationally influenced by the larger galaxy. The Whale Galaxy is a challenging but rewarding target for observers due to its intriguing morphology and complex structure.

NGC 4449: NGC 4449 is an irregular galaxy located approximately 12 million light-years away from Earth in the constellation Canes Venatici. It is characterized by its irregular shape and intense regions of star formation, which give it a mottled appearance in optical telescopes. NGC 4449 is undergoing a period of rapid star formation, likely triggered by interactions with neighboring galaxies.