The Cetus Constellation

Welcome back to Constellation Friday! Today, in honor of the late and great Tammy Plotner, we will be dealing with the sea monster – the Cetus constellation!

In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.

One of these constellations is Cetus, which was named in honor of the sea monster from Greek mythology.  Cetus is the fourth largest constellation in the sky, the majority of which resides just below the ecliptic plane. Here, it is bordered by many “watery” constellations – including Aquarius, Pices, Eridanus, Piscis Austrinus, Capricornus – as well as Aries, Sculptor, Fornax and Taurus. Today, it is one of the 88 modern constellations recognized by the IAU.

Name and Meaning:

In mythology, Cetus ties in with the legendary Cepheus,Cassiopeia, Andromeda, Perseus tale – for Cetus is the monster to which poor Andromeda was to be sacrificed. (This whole tale is quite wonderful when studied, for we can also tie in Pegasus as Perseus’ horse, Algol and the whom he slew to get to Andromeda and much, much more!)

Cetus, as represented by Sidney Hall in this card from Urania’s Mirror (1825). Credit: Library of Congress/Sidney Hall

As for poor, ugly Cetus. He also represents the gates to the underworld thanks to his position just under the ecliptic plane. Arab legend has it that Cetus carries two pearl necklaces – one broken and the other intact – which oddly enough, you can see among its faint stars in the circular patterns when nights are dark. No matter what the legends are, Cetus is an rather dim, but interesting constellation!

History of Observation:

Cetus was one of many Mesopotamian constellations that passed down to the Greeks. Originally, Cetus may have been associated with a whale, and is often referred to as the Whale. However, its most common representation is that of the sea monster that was slain by Perseus.

In the 17th century, Cetus was depicted variously as a “dragon fish” (by Johann Bayer), and as a whale-like creature by famed 17th-century cartographers Willem Blaeu and Andreas Cellarius. However, Cetus has also been variously depicted with animal heads attached to an aquatic animal body.

The constellation is also represented in many non-Western astrological systems.In Chinese astronomy, the stars of Cetus are found among the Black Tortoise of the North (B?i F?ng Xuán W?) and the White Tiger of the West (X? F?ng Bái H?).

Cetus, as depicted by famed 17th century cartographer Willem Blaeu, 1602. Credit: WIkipedia Commons/Erik Lernestål

Notable Features:

Cetus sprawls across 1231 square degrees of sky and contains 15 main stars, highlighted by 3 bright stars and 88 Bayer/Flamsteed designations. It’s brightest star is Beta Ceti, otherwise known as Deneb Kaitos (Diphda), a type K0III orange giant which is located approximately 96.3 light years away. This star has left its main sequence and is on its way to becoming a red giant.

The name Deneb Kaitos is derived from the Arabic “Al Dhanab al Kaitos al Janubiyy”, which translates as “the southern tail of Cetus”. The name Diphda comes “ad-dafda at-tani“, which is Arabic for “the second frog” – the star Fomalhaut in neighboring Piscis Austrinus is usually referred to as the first frog.)

Then there’s Alpha Ceti, a very old red giant star located approximately 249 light years from Earth. It’s traditional name (Menkar), is derived from the Arabic word for “nostril”. Then comes Omicron Ceti, also known as Mira, binary star consisting located approximately 420 light years away. This binary system consists of an oscillating variable red giant (Mira A).

After being recorded for the first time by David Fabricius (on August 3, 1596), Mira has since gone on to become the prototype for the Mira class of variables (of which there are six or seven thousand known examples). These stars are red giants whose surfaces oscillate in such a way as to cause variations in brightness over periods ranging from 80 to more than 1,000 days.

Composite image of Messier 77 (NGC 1068), showing it in the visible, X-ray, and radio spectrums. Credit: NASA/CXC/MIT/C.Canizares/D.Evans et al/STScI/NSF/NRAO/VLA

Cetus is also home to many Deep Sky Objects. A notable examples is the barred spiral galaxy known as Messier 77, which is located approximately 47 million light years away and is 170,000 light years in diameter, making it one of the largest galaxies listed in Messier’s catalogue. It has an Active Galactic Nucleus (AGN) which is obscured from view by intergalactic dust, but remains an active radio source.

Then there’s NGC 1055, a spiral galaxy that lies just 0.5 north by northeast of Messier 77. It is located approximately 52 million light years away and is seen edge-on from Earth. Next to Messier 77, NGC 1055 is a largest member of a galaxy group – measuring 115,800 light years in diameter – that also includes NGC 1073 and several smaller irregular galaxies. It has a diameter of about 115,800 light years. The galaxy is a known radio source.

Finding Cetus:

Cetus is the fourth largest constellation in the sky, is visible at latitudes between +70° and -90° and is best seen at culmination during the month of November. Of all the stars in Cetus, the very first you must look for in binoculars is Mira. Omicron Ceti was the very first variable star discovered and was perhaps known as far back as ancient China, Babylon or Greece. The variability was first recorded by the astronomer David Fabricius while observing Mercury.

Now aim your binoculars at Alpha Ceti. It’s name is Menkar and we do know something about it. Menkar is an old and dying star, long past the hydrogen and perhaps even past the helium stage of its stellar evolution. Right now it’s a red giant star but as it begins to burn its carbon core it will likely become highly unstable before finally shedding its outer layers and forming a planetary nebula, leaving a relatively large white dwarf remnant.

Location of Mira and Tau Ceti. Credit: Constellation Guide/Torsten Bronger

Hop down to Beta Ceti – Diphda. Oddly enough, Diphda is actually the brightest star in Cetus, despite its beta designation. It is a giant star with a stellar corona that’s brightening with age – exerting about 2000 times more x-ray power than our Sun! For some reason, it has gone into an advanced stage if stellar evolution called core helium burning – where it is converting helium directly to carbon.

Are you ready to get out your telescope now? Then aim at Diphda and drop south a couple of degrees for NGC 247. This is a very definite spiral galaxy with an intense “stellar” nucleus! Sitting right up in the eyepiece as a delightful oval, the NGC 247 is has a very proper galaxy structure with a defined core area and a concentration that slowly disperses toward its boundaries with one well-defined dark dust lane helping to enhance a spiral arm. Most entertaining! Continuing “down” we move on to the NGC 253. Talk about bright!

Very few galactic studies come in this magnitude (small telescopes will pick it up very well, but it requires large aperture to study structure.) Very elongated and hazy, it reminds me sharply of the “Andromeda Galaxy”. The center is very concentrated and the spiral arms wrap their way around it beautifully! Dust lanes and bright hints of concentration are most evident. and its most endearing feature is that it seems to be set within a mini “Trapezium” of stars. A very worthy study…

Now, let’s hop off to Delta Ceti, shall we? I want to rock your world – because spiral galaxy M77 rocked mine! Once again, easily achieved in the small telescope, Messier 77 comes “alive” with aperture. This one has an incredible nucleus and very pronounced spiral arms – three big, fat ones! Underscored by dark dust lanes, the arms swirl away from the center in a galactic display that takes your breath away!

The location of the Cetus Constellation. Credit: IAU/Sky&Telescope magazine

The “mottling” inside the structure is not just a hint in this ovalish galaxy. I guarantee you won’t find this one “ho hum”… how could you when you know you’re looking at something that’s 47.0 million light-years away! Messier 77 is an active galaxy with an Active Galactic Nucleus (AGN) and one of the brightest Seyfert galaxies known.

Now, return to Delta and the “fall line” runs west to east on the north side. First up is galaxy NGC 1073, a very pretty little spiral galaxy with a very “stretched” appearing nucleus that seems to be “ringed” by its arms! Continuing along the same trajectory, we find the NGC 1055. Oh, yes… Edge-on, lenticular galaxy! This soft streak of light is accompanied by a trio of stars. The galaxy itself is cut through by a dark dust lane, but what appears so unusual is the core is to one side!

Now we’ve made it to back to the incredible M77, but let’s keep on the path and pick up the NGC 1087 – a nice, even-looking spiral galaxy with a bright nucleus and one curved arm. Ready to head for the beautiful variable Mira again? Then let her be the guide star, because halfway between there and Delta is the NGC 936 – a soft spiral galaxy with a “saturn” shaped nucleus. Nice starhoppin’!

We have written many interesting articles about the constellation here at Universe Today. Here is What Are The Constellations?What Is The Zodiac?, and Zodiac Signs And Their Dates.

Be sure to check out The Messier Catalog while you’re at it!

For more information, check out the IAUs list of Constellations, and the Students for the Exploration and Development of Space page on Canes Venatici and Constellation Families.

Sources:

The Canis Major Constellation

Welcome back to Constellation Friday! Today, in honor of the late and great Tammy Plotner, we will be dealing with the “big dog” itself – the Canis Major constellation!

In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.

One of these constellations included in Ptolemy’s collection was Canis Major, an asterism located in the southern celestial hemisphere. As one of two constellations representing “the dogs” (which are associated with “the hunter” Orion) this constellation contains many notable stars and Deep Sky Objects. Today, it is one of the 88 constellations recognized by the IAU, and is bordered by Monoceros, Lepus, Columba and Puppis.

Name and Meaning:

The constellation of Canis Major literally translates to “large dog” in Latin. The first recorded mentions of any of the stars associated with this asterism are traced back to Ancient Mesopotamia, where the Babylonians recorded its existence in their Three Star Each tablets (ca. 1100 BCE). In this account, Sirus (KAK.SI.DI) was seen as the arrow aimed towards Orion, while Canis Major and part of Puppis were seen as a bow.

Artist's impression of a white dwarf star in orbit around Sirius (a white supergiant). Credit: NASA, ESA and G. Bacon (STScI)
Artist’s impression of a white dwarf star in orbit around Sirius (a white supergiant). Credit: NASA, ESA and G. Bacon (STScI)

To the ancient Greeks, Canis Major represented a dog following the great hunter Orion. Named Laelaps, or the hound of Prociris in some accounts, this dog was so swift that Zeus elevated it to the heavens. Its Alpha star, Sirius, is the brightest object in the sky (besides the Sun, the Moon and nearest planets). The star’s name means “glowing” or “scorching” in Greek, since the summer heat occurred just after Sirius’ helical rising.

The Ancient Greeks referred to such times in the summer as “dog days”, as only dogs would be mad enough to go out in the heat. This association is what led to Sirius coming to be known as the “Dog Star”. Depending on the faintness of stars considered, Canis Major resembles a dog facing either above or below the ecliptic. When facing below, since Sirius was considered a dog in its own right, early Greek mythology sometimes considered it to be two headed.

Together with the area of the sky that is deserted (now considered as the new and extremely faint constellations Camelopardalis and Lynx), and the other features of the area in the Zodiac sign of Gemini (i.e. the Milky Way, and the constellations Gemini, Orion, Auriga, and Canis Minor), this may be the origin of the myth of the cattle of Geryon, which forms one of The Twelve Lab ours of Heracles.

Sirius and the "Summer Triangle", . Credit: Greg Bacon/ STScI/ESA/NASA
Artist’s impression of Sirius and the “Summer Triangle”. Credit: G. Bacon (STScI)/ESA/NASA

Sirius has been an object of wonder and veneration to all ancient peoples throughout human history. In fact, the Arabic word Al Shi’ra resembles the Greek, Roman, and Egyptian names suggesting a common origin in Sanskrit, in which the name Surya (the Sun God) simply means the “shining one.” In the ancient Vedas this star was known as the Chieftain’s star; and in other Hindu writings, it is referred to as Sukra – the Rain God, or Rain Star.

Sirius was revered as the Nile Star, or Star of Isis, by the ancient Egyptians. Its annual appearance just before dawn at the Summer Solstice heralded the flooding of the Nile, upon which Egyptian agriculture depended. This helical rising is referred to in many temple inscriptions, where the star is known as the Divine Sepat, identified as the soul of Isis.

To the Chinese, the stars of Canis Major were associated with several different asterisms – including the Military Market, the Wild Cockerel, and the Bow and Arrow. All of these lay in the Vermilion Bird region of the zodiac, on of four symbols of the Chinese constellations, which is associated with the South and Summer.  In this tradition, Sirius was known Tianlang (which means “Celestial Wolf”) and denoted invasion and plunder.

This constellation and its most prominent stars were also featured in the astrological traditions of the Maori people of New Zealand, the Aborigines of Australia, and the Polynesians of the South Pacific.

Isis depicted with outstretched wings in an ancient wall painting (ca. 1360 BCE). Credit: Wikipedia Commons/Ägyptischer Maler
Isis depicted with outstretched wings in an ancient wall painting (ca. 1360 BCE). Credit: Wikipedia Commons/Ägyptischer Maler

History of Observation:

This constellation was one of the original 48 that Ptolemy included in his 2nd century BCE work the Amalgest. It would remain a part of the astrological traditions of Europe and the Near East for millennia. The Romans would later add Canis Minor, appearing as Orion’s second dog, using stars to the north-west of Canis Major.

In medieval Arab astronomy, the constellation became Al Kalb al Akbar, (“the Greater Dog”), which was transcribed as Alcheleb Alachbar by European astronomers by the 17th century. In 1862, Alvan Graham Clark, Jr. made an interesting discovery while testing an 18″ refractor telescope at the Dearborn Observatory at Northwestern University in Illinois.

In the course of observing Sirius, he discovered that the bright star had a faint companion – a white dwarf later named Sirius B (sometimes called “the Pup”). These observations confirmed what Friedrich Bessel proposed in 1844, based on measurements of Sirius A’s wobble. In 1922, the International Astronomical Union would include Canis Major as one of the 88 recognized constellations.

Canis Major as depicted in Urania's Mirror, a set of constellation cards published in London c.1825. Credit: Library of Congress
Canis Major as depicted in Urania’s Mirror, a set of constellation cards published in London c.1825. Credit: Library of Congress

Notable Features:

Canis Major has several notable stars, the brightest being Sirius A. It’s luminosity in the night sky is due to its proximity (8.6 light years from Earth), and the fact that it is a magnitude -1.6 star. Because of this, it produces so much light that it often appears to be flashing in vibrant colors, an effect caused by the interaction of its light with our atmosphere.

Then there’s Beta Canis Majoris, a variable magnitude blue-white giant star whose traditional name (Murzim) means the “The Heralder”. It is a Beta Cephei variable star and is currently in the final stages of using its hydrogen gas for fuel. It will eventually exhaust this supply and begin using helium for fuel instead. Beta Canis Majoris is located near the far end of the Local Bubble – a cavity in the local Interstellar medium though which the Sun is traveling.

Next up is Eta Canis Majoris, known by its traditional name as Aludra (in Arabic, “al-aora”, meaning “the virgin”). This star shines brightly in the skies in spite of its distance from Earth (approx. 2,000 light years from Earth) due to it being many times brighter (absolute magnitude) than the Sun. A blue supergiant, Aludra has only been around a fraction of the time of our Sun, yet is already in the last stages of its life.

Another “major” star in this constellation is VY Canis Majoris (VY CMa), a red hypergiant star located in the constellation Canis Major. In addition to being one of the largest known stars, it is also one of the most luminous ever observed. It is located about 3,900 light years (~1.2 kiloparsecs) away from Earth and is estimated to have 1,420 solar radii.

VY Canis Majoris. The biggest known star.
Size comparison between the Sun and VY Canis Majoris, which once held the title of the largest known star in the Universe. Credit: Wikipedia Commons/Oona Räisänen

Canis Major is also home to several Deep Sky Objects, the most notable being Messier 41 (NGC 2287). Containing about 100 stars, this impressive star cluster contains several red giant stars. The brightest of these is spectral type K3, and located near M41’s center. The cluster is estimated to be between 190 and 240 million years old, and its is believed to be 25 to 26 light years in diameter.

Then there’s the galactic star cluster NGC 2362. First seen by Giovanni Hodierna in 1654 and rediscovered William Herschel in 1783, this magnificent star cluster may be less than 5 million years old and show shows signs of nebulosity – the remains of the gas cloud from which it formed. What makes it even more special is the presence of Tau Canis Major.

Easily distinguished as the brightest star in the cluster, Tau is a luminous supergiant of spectral type O8. With a visual magnitude of 4.39, it is 280,000 times more luminous than Sol. Tau CMa is also brighter component of a spectroscopic binary and studies of NGC 2362 suggest that it will survive longer than the Pleiades cluster (which will break up before Tau does), but not as long as the Hyades cluster.

Then there’s NGC 2354, a magnitude 6.5 star cluster. While it will likely appear as a small, hazy patch to binoculars, NGC 2354 is actually a rich galactic cluster containing around 60 metal-poor members. As aperture and magnification increase, the cluster shows two delightful circle-like structures of stars.

The Canis Major Dwarf Galaxy - the Milky Way's current dinner. Image Credit: APOD
The Canis Major Dwarf Galaxy – currently recognized as being the closet neighbor to the Milky Way. Credit: APOD

For large telescopes and GoTo telescopes, there are several objects worth studying, like the Canis Major Dwarf Galaxy (RA 7 12 30 Dec -27 40 00). An irregular galaxy that is now thought to be the closest neighboring galaxy to our part of the Milky Way, it is located about 25,000 light-years away from our Solar System and 42,000 light-years from the Galactic Center.

It has a roughly elliptical shape and is thought to contain as many stars as the Sagittarius Dwarf Elliptical Galaxy, which was discovered in 2003 and thought to be the closest galaxy at the time. Although closer to the Earth than the center of the galaxy itself, it was difficult to detect because it is located behind the plane of the Milky Way, where concentrations of stars, gas and dust are densest.

Globular clusters thought to be associated with the Canis Major Dwarf galaxy include NGC 1851, NGC 1904, NGC 2298 and NGC 2808, all of which are likely to be a remnant of the galaxy’s globular cluster system before its accretion (or swallowing) into the Milky Way. NGC 1261 is another nearby cluster, but its velocity is different enough from that of the others to make its relation to the system unclear.

Finding Canis Major:

Finding Canis Major is quite easy, thanks to the presence of Sirius – the brightest star to grace the night sky. All you need to do is find Orion’s belt, discern the lower left edge of constellation (the star Kappa Orionis, or Saiph), and look south-west a few degrees. There, shining in all it glory, will be the “Dog Star”, with all the other stars stemming outwards from it.

The location of the Canis Major constellation in the southern sky. Credit: IAU
The location of the Canis Major constellation in the southern sky. Credit: IAU

Unfortunately, Sirius A’s luminosity means that the means that poor “Pup” hardly stands a chance of being seen. At magnitude 8.5 it could easily be caught in binoculars if it were on its own. To find it, you’ll need a mid-to-large telescope with a high power eyepiece and good viewing conditions – a stable evening (not night) when Sirius is as high in the sky as possible. It will still be quite faint, so spotting it will take time and patience.

Between Sirius at the northern tip, and Adhara at the south, you can also spot M41 residing almost about halfway. Using binoculars or telescopes, all one need do is aim about 4 degrees south of Sirius – about one standard field of view for binoculars, about one field of view for the average telescope finderscope, and about 6 fields of view for the average wide field, low power eyepiece.

Thousands of years later, Canis Major remains an important part of our astronomical heritage. Thanks largely to Sirius, for burning so brightly, it has always been seen as a significant cosmological marker. But as our understanding of the cosmos has improved (not to mention our instruments) we have come to find just how many impressive stars and stellar objects are located in this region of space.

We have written many interesting articles about the constellation here at Universe Today. Here is What Are The Constellations?What Is The Zodiac?, and Zodiac Signs And Their Dates.

Be sure to check out The Messier Catalog while you’re at it!

For more information, check out the IAUs list of Constellations, and the Students for the Exploration and Development of Space page on Canes Venatici and Constellation Families.

Sources:

 

The Canes Venatici Constellation

Welcome back to Constellation Friday! Today, in honor of the late and great Tammy Plotner, we will be dealing with Canes Venatici constellation.

In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. His treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come. Today, this list has been expanded to include the 88 constellations recognized by the IAU.

One of these is known as Canes Venatici, a small northern constellation that is bordered by Ursa Major to the north and west, Coma Berenices to the south, and Boötes to the east. Canes Venatici belongs to the Ursa Major family of constellations, along with Boötes, Camelopardalis, Coma Berenices, Corona Borealis, Draco, Leo Minor, Lynx, Ursa Major, and Ursa Minor.

Name and Meaning:

The small northern constellation of Canes Venatici represents the hunting dogs – Chara and Asterion – of Boötes. It is also one of three constellations that represent dogs, along with Canis Major and Canis Minor. Given its comparatively recent origin, there is no real mythology associated with this asterism. However, it does have an interesting history.

Canes Venatici depicted in Hevelius's star atlas. Note that, per the conventions of the time, the image is mirrored. Credit: Wikipedia Commons/Atlas Coelestis
Canes Venatici depicted in Hevelius’s star atlas. Note that, per the conventions of the time, the image is mirrored. Credit: Wikipedia Commons/Atlas Coelestis

History of Observation:

During Classic Antiquity, the stars of Canes Venatici did not appear very brightly in the night sky. As such, they were listed by Ptolemy as unfigured stars below the constellation Ursa Major in the Almagest, rather than as a distinct constellation. During the Middle Ages, the identification of these stars as being the dogs of Boötes arose due to a mistranslation.

Some of the component stars in the nearby constellation of Boötes (which was known as the “herdsman”) were traditionally described as representing his cudgel. When the Almagest was translated from Greek to Arabic, the translator – the Arab astronomer Hunayn ibn Ishaq – did not know the Arabic word for cudgel.

As such, he chose the closest translation in Arabic – “al-`asa dhat al-kullab” -which literally means “the spearshaft having a hook” (possibly in reference to a shepherd’s crook). When the Arabic text was later translated into Latin, the translator mistook the Arabic word “kullab” for “kilab” – which means “dogs” – and wrote the name as hastile habens canes (“spearshaft having dogs”).

This representation of Boötes having two dogs remained popular and became official when, in 1687, Johannes Hevelius decided to designate them as a separate constellation. The northern of the two hunting dogs was named Asterion (‘little star’) while the southern dog was named Chara – from the Greek word for ‘joy’,.

Canes Venatici can be seen in the orientation they appear to the eyes in this 1825 star chart from Urania's Mirror. Credit: Wikipedia Commons/Library of Congress
Canes Venatici can be seen in the orientation they appear to the eyes in this 1825 star chart from Urania’s Mirror. Credit: Wikipedia Commons/Library of Congress

Notable Features:

The constellation’s brightest star is Cor Caroli, which is perhaps one of the most splendid of all colorful double stars. The name literally means “Charles’ heart”, and was named by Sir Charles Scarborough in honor of Charles I – who was executed in the aftermath of the English Civil War. The star is also associated with Charles II of England, who was restored to the throne after the interregnum following his father’s death.

Cor Caroli is a binary star with a combined apparent magnitude of 2.81 which marks the northern vertex of the Diamond of Virgo asterism. The two stars are 19.6 arc seconds apart and are easily resolved in small telescopes and steady binoculars. The system lies approximately 110 light years from Earth. It’s main star, a² Canum Venaticorum, is the prototype of a class of Spectral Type A0 variable stars (the so-called a² Canum Venaticorum stars).

These stars have a strong stellar magnetic field, which is believed to produce starspots of enormous extent. Due to these starspots, the brightness of a² Canum Venaticorum stars varies considerably during their rotation. Their brightness also varies between magnitude +2.84 and +2.98 with a period of 5.47 days.  The companion, a¹ Canum Venaticorum (a spectral type F0 star), is considerably fainter at +5.5 magnitude.

Y CVn, and a simulation of what it would look like close-up, created using Celestia. Credit: Wikipedia Commons/Kirk39
Y CVn, “La Superba”, and a simulation of what it would look like close-up, created using Celestia. Credit: Wikipedia Commons/Kirk39

Next up is Y Canum Venaticorum (Y CVn), which was named “La Superba” by 19th century astronomer Angelo Secchi for its uncommonly beautiful red color. This name was certainly appropriate, since it is  one of the reddest stars in the sky, and one the brightest of the giant red “carbon stars”.

La Superba is the brightest J-star in the sky, a very rare category of carbon stars that contain large amounts of carbon-13. Its surface temperature is believed to be about 2800 K (~2526 °C; 4580 °F), making it one of the coldest  true stars known. Its appearance, temperature and composition are all indications that it is currently in the Red Giant phase of its life-cycle.

Y CVn is almost never visible to the naked eye since most of its output is outside the visible spectrum. Yet, when infrared radiation is considered, Y CVn has a luminosity 4400 times that of the Sun, and its radius is approximately 2 AU. If it were placed at the position of our sun, the star’s surface would extend beyond the orbit of Mars.

Canes Venatici is also home to several Deep Sky Objects. For starters, there’s the tremendous globular cluster known as Messier 3 (M3). Messier 3 has an apparent magnitude of 6.2, making it visible to the naked eye. It was first resolved into stars by William Herschel around 1784. This cluster is one of the largest and brightest, made up of around 500,000 stars, and is located about 33,900 light-years away from our solar system.

The 51st entry in Charles Messier's famous catalog is perhaps the original spiral nebula--a large galaxy with a well defined spiral structure also cataloged as NGC 5194. Over 60,000 light-years across, M51's spiral arms and dust lanes clearly sweep in front of its companion galaxy, NGC 5195. Image data from the Hubble's Advanced Camera for Surveys was reprocessed to produce this alternative portrait of the well-known interacting galaxy pair. The processing sharpened details and enhanced color and contrast in otherwise faint areas, bringing out dust lanes and extended streams that cross the small companion, along with features in the surroundings and core of M51 itself. The pair are about 31 million light-years distant. Not far on the sky from the handle of the Big Dipper, they officially lie within the boundaries of the small constellation Canes Venatici. Image Credit: NASA
Messier 51, aka. the Whirlpool Galaxy, is a spiral nebula – a large galaxy with a well defined spiral structure located over 60,000 light-years across. Credit: NASA

Then there’s the Whirlpool Galaxy, also known as Messier 51 or NGC 5194. This  interacting, grand-design spiral galaxy is located at a distance of approximately 23 million light-years from Earth. It is one of the most famous spiral galaxies in the night sky, for both its grace and beauty. The galaxy and its companion (NGC 5195) are easily observed by amateur telescopes, and the two galaxies may even be seen with larger binoculars.

Canes Venatici is also home of the Sunflower Galaxy (aka. Messier 63 and NGC 5055), an unbarred spiral galaxy consisting of a central galactic disc surrounded by many short spiral arm segments. It is part of the M51 galaxy group, which also includes the Whirlpool Galaxy (M51). In the mid-1800s, Lord Rosse identified the spiral structure within the galaxy, making this one of the first galaxies in which “spiral nebulae” were identified.

Now hop over to the barred spiral galaxy known as Messier 94 for some comparison. It was discovered by Pierre Méchain in 1781 and catalogued by Charles Messier two days later. Although some references describe M94 as a barred spiral galaxy, the “bar” structure appears to be more oval-shaped. The galaxy is also notable in that it has two ring structures, an inner ring with a diameter of 70″ and an outer ring with a diameter of 600″.

These rings appear to form at resonance locations within the disk of the galaxy. The inner ring is the site of strong star formation activity and is sometimes referred to as a starburst ring. This star formation is fueled by gas that is dynamically driven into the ring by the inner oval-shaped bar-like structure.

Messier 63, also known as the Sunflower Galaxy, seen here in a new image from the NASA/ESA Hubble Space Telescope. Credit: NASA/ESA/HST
Messier 63, also known as the Sunflower Galaxy, seen here in an image from the  Hubble Space Telescope. Credit: NASA/ESA/HST

For a completely different galaxy, try Messier 106 (NGC 4258). This spiral galaxy is about 22 to 25 million light-years away from Earth. It is also a Seyfert II galaxy, which means that due to x-rays and unusual emission lines detected, it is suspected that part of the galaxy is falling into a supermassive black hole in the center. Nearby NGC 4217 is a possible companion galaxy.

The constellation does not have any stars with known planets, and there is one meteor shower associated with the constellation – the Canes Venaticids.

Finding Canes Venatici:

While it basically consists of only two bright stars, the Canes Venatici constellation is still fairly easy to locate and is bordered by Ursa Major, Boötes and Coma Berenices. It can be spotted with the naked eye on a clear night where light conditions are favorable. However, for those using binoculars, finderscopes and small telescopes, the constellation has much to offer the amateur astronomer and stargazer.

The location of the Canes Venatici constellation. Credit: IAU and Sky&Telescope magazine
The location of the Canes Venatici constellation. Credit: IAU/Sky&Telescope magazine

It’s brightest star, Cor Calroli can be found at RA 12h 56m 01.6674s Dec +38° 19′ 06.167″, while beautiful Y Canum Venaticorum (aka. “La Superba”) can be seen at RA 12f 45m 07s Dec +45° 26′ 24″. And M51 is easy to find by following the easternmost star of the Big Dipper, Eta Ursae Majoris, and going 3.5° southeast. Its declination is +47°, so it is circumpolar for observers located above 43°N latitude.

We have written many interesting articles about the constellation here at Universe Today. Here is What Are The Constellations?What Is The Zodiac?, and Zodiac Signs And Their Dates.

Be sure to check out The Messier Catalog while you’re at it!

For more information, check out the IAUs list of Constellations, and the Students for the Exploration and Development of Space page on Canes Venatici and Constellation Families.

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