Ursa Major Constellation

Ursa Major constellation lies in the northern sky. Its name means “the great bear” or “the larger bear” in Latin. The smaller bear is represented by Ursa Minor. Ursa Major is the largest northern constellation and the third largest constellation in the sky. Its brightest stars form the Big Dipper asterism (the Plough), one of the most recognizable star patterns in the night sky.

The Great Bear constellation is well known in many world cultures and associated with many different myths. It was one of the constellations catalogued by the Greek astronomer Ptolemy in the 2nd century CE. In Greek mythology, it is associated with the myth of Callisto, a nymph who was turned into a bear by Zeus’ jealous wife Hera.

Ursa Major contains many notable stars and famous deep sky objects. The brightest deep sky objects in the constellation include the Pinwheel Galaxy (M101), Bode’s Galaxy (M81) the Cigar Galaxy (M82), and the Owl Nebula (M97).

Facts, location and map

Ursa Major is the third largest constellation in the sky, after Hydra and Virgo. It occupies an area of 1280 square degrees. It is located in the second quadrant of the northern hemisphere (NQ2). The entire constellation can be seen from locations between the latitudes +90° and -30°.

The neighboring constellations are Boötes, Camelopardalis, Canes Venatici, Coma Berenices, Draco, Leo, Leo Minor and Lynx.

The constellation name Ursa Major is pronounced /ˌɜːrsə ˈmeɪdʒər/. In English, the constellation is known as the Great Bear. The genitive form of Ursa Major, used in star names, is Ursae Majoris (pronunciation: /ˌɜːrsiː məˈdʒɒrɪs/). The three-letter abbreviation, adopted by the International Astronomical Union (IAU) in 1922, is UMa.

Ursa Major contains seven Messier objects: Messier 40 (M40, Winnecke 4), Messier 81 (M81, NGC 3031, Bode’s Galaxy), Messier 82 (M82, NGC 3034, Cigar Galaxy), Messier 97 (M97, NGC 3587, Owl Nebula), Messier 101 (M101, NGC 5457, Pinwheel Galaxy), Messier 108 (M108, NGC 3556, Surfboard Galaxy), and Messier 109 (M109, NGC 3992).

The Great Bear constellation contains 21 stars with confirmed planets. The stars with multiple planets include Chalawan (47 UMa) and HIP 57274 with three orbiting planets each and HD 89744 and Násti (HD 68988) with two planets each.

The brightest star in Ursa Major is Alioth, Epsilon Ursae Majoris. The evolved A-type star has an apparent magnitude of 1.77 and lies 82.6 light-years away. It is the 32nd brightest star in the night sky.

The constellation Ursa Major contains 22 formally named stars. The star names approved by the International Astronomical Union (IAU) are Alcor (80 Ursae Majoris A), Alioth (Epsilon Ursae Majoris), Alkaid (Eta Ursae Majoris), Alkaphrah (Kappa Ursae Majoris A), Alula Australis (Xi Ursae Majoris Aa), Alula Borealis (Nu Ursae Majoris), Aniara (HD 102956), Chalawan (47 Ursae Majoris), Dombay (HAT-P-3), Dubhe (Alpha Ursae Majoris A), Intercrus (41 Lyncis), Liesma (HD 118203), Mazalaai (HAT-P-21), Megrez (Delta Ursae Majoris), Merak (Beta Ursae Majoris), Mizar (Zeta Ursae Majoris Aa), Muscida (Omicron Ursae Majoris A), Násti (HD 68988), Phecda (Gamma Ursae Majoris A), Taiyangshou (Chi Ursae Majoris), Talitha (Iota Ursae Majoris Aa), Tania Australis (Mu Ursae Majoris A), and Tania Borealis (Lambda Ursae Majoris).

There are two meteor showers associated with the constellation: the Alpha Ursae Majorids and the Leonids-Ursids.

Ursa Major belongs to the Ursa Major family of constellations, along with Boötes, Camelopardalis, Canes Venatici, Coma Berenices, Corona Borealis, Draco, Leo Minor, Lynx, and Ursa Minor.

The best time of the year to see Ursa Major is during the month of April, when the constellation appears high above the horizon at 9 pm. The Great Bear is circumpolar to most northern observers but never rises very high in the sky for observers in the southern hemisphere.

Myth

Ursa Major is a well-known, significant constellation in many cultures. It is one of the oldest constellations in the sky, with a history dating back to ancient times. The constellation is referenced in Homer and the Bible. A great number of tales and legends across the globe associate Ursa Major with a bear.

Ancient Greeks associated the constellation with the myth of Callisto, the beautiful nymph who had sworn a vow of chastity to the goddess Artemis. Zeus saw the nymph one day and fell in love. The two had a son, and named him Arcas. Artemis had already banished Callisto when she had learned about the nymph’s pregnancy and broken vow.

Zeus’ jealous wife Hera was not amused by her husband’s actions. Angered by Zeus’ betrayal, she turned Callisto into a bear.

Callisto lived as a bear for the next 15 years, roaming the forest and always running and hiding from hunters. One day, her son Arcas was walking in the forest and the two came face to face. At the sight of the bear, Arcas quickly drew his spear.

Seeing the scene from Olympus, Zeus intervened to prevent a tragedy. He sent a whirlwind that carried both Callisto and Arcas into the heavens, where he turned Arcas into the constellation Boötes, the Herdsman, and Callisto into Ursa Major. (In another version, Arcas becomes the constellation Ursa Minor.) This only further infuriated Hera and she persuaded her foster parents Oceanus and Tethys never to let the bear bathe in the northern waters. This, according to the legend, is why Ursa Major never sets below the horizon in the mid-northern latitudes.

In a different version of the tale, it is not Hera but Artemis who transforms Callisto into a bear. Artemis does this to punish the nymph for breaking her vow of chastity to the goddess. Many years later, both Callisto and Arcas are captured in the forest and taken to King Lycaon as a gift. The mother and son take refuge in the temple of Zeus, and the god intervenes and saves them, placing them both in the sky.

There is an entirely different Greek myth associated with Ursa Major. It involves two bears that saved Zeus from his father Cronus (or Cronos) and nourished him for a year.

A more familiar version of the story involves Adrasteia, one of the nymphs who took care of Zeus when he was very young. In Greek lore, Zeus’ father Cronus was told by an oracle that one of his children would eventually overthrow him. Fearful of the prophecy, Cronus swallowed all his children until Zeus was born. Rhea, Zeus’ mother, smuggled their youngest child to the island of Crete, where the nymphs Adrasteia and Ida nursed young Zeus for a year. In this version of the myth, Ida is associated with the constellation Ursa Minor. Amaltheia, the goat that nursed Zeus, was placed in the sky as the bright star Capella in the constellation Auriga. The prophecy eventually came true. Zeus overthrew Cronus and freed his brothers Hades and Poseidon and sisters Demeter, Hera and Hestia.

The Romans called the constellation Septentrio, or “seven plough oxen,” even though only two of the seven stars represented oxen, while the others formed a wagon. The name was also used for Ursa Minor.

Ursa Major is associated with many different forms in the sky in different cultures, including the camel, shark, skunk, sickle, bushel and canoe. The Chinese know the seven brightest stars, or Tseih Sing, as the Government, or Pih Tow, the Northern Measure.

In Hindu legend, the brightest stars of Ursa Major represent the Seven Sages and the constellation is known as Saptarshi. The sages in question are Bhrigu, Atri, Angirasa, Vasishta, Pulastya, Pulalaha and Kratu.

In some Native American tales, the bowl of the Big Dipper represents a large bear and the stars that mark the handle of the Dipper are the warriors chasing it. Since the constellation is pretty low in the sky in autumn, the legend says that it is the blood of the wounded bear that causes the leaves to turn red.

In more recent American history, the Big Dipper played a role in the Underground Railroad, as its position in the sky helped escaped slaves find their way north. There were numerous songs that spread in the south that said to follow the ‘Drinking Gourd’ to get to a better life.

Asterisms

Big Dipper

The Big Dipper is one of the most recognizable asterisms in the night sky. Formed by seven bright Ursa Major stars, the star pattern is visible even from light-polluted areas. For observers in the northern hemisphere, it stays above the horizon throughout the year.

The Big Dipper is formed by Dubhe (Alpha UMa), Merak (Beta UMa), Phecda (Gamma UMa), Megrez (Delta UMa), Alioth (Epsilon UMa), Mizar (Zeta UMa), and Alkaid (Eta UMa). Alkaid, Mizar and Alioth form the Big Dipper’s handle, and Phecda, Megrez, Dubhe and Merak outline the bowl.

The Big Dipper’s handle can be used to find the bright star Arcturus, the bear keeper. Arcturus is the brightest star in the northern celestial hemisphere and the lucida of the constellation Boötes (the Herdsman). The star’s name is derived from the Greek ἄρκτος (arktos), meaning “bear,” and οὖρος (ouros), “watcher” or “guardian.”

Following the curved line past Arcturus leads to Spica, the brightest star in the constellation Virgo and the 16th brightest star in the sky.

The Big Dipper has significance in many cultures and is known by many different names. These include the Plough, Charles’ Wain, the Seven Oxen, the Great Wagon, the Saucepan, the Seven Sages, and the Northern Dipper.

Pointer Stars

Merak and Dubhe, the outer stars of the Big Dipper’s bowl, are known as the Pointer Stars (or simply the Pointers). They point in the direction of Polaris, the nearest visible star to the northern celestial pole. A line extended from Merak through Dubhe leads to the North Star.

Polaris is the brightest star in Ursa Minor (the Little Bear). It marks the tip of the Little Bear’s tail and the end of the Little Dipper’s handle. The middle stars of the Little Dipper are quite faint and difficult to make out in less-than-ideal conditions, which is why the two brighter stars of the Big Dipper are commonly used to find the pole star and true north.

Horse and Rider

The stars Mizar and Alcor form a visual double star that was known as the Horse and Rider in Arabic astronomy. Mizar is the middle star of the Big Dipper’s handle and Alcor is its fainter companion. The two stars were long believed to be unrelated but are now known to form a multiple star system.

Three Leaps of the Gazelle

The Three Leaps of the Gazelle is an old Arabic asterism formed by three pairs of stars that mark the Great Bear’s feet. It represents the leaps of a gazelle that dashed across a pond after seeing a lion. The pond is represented by the constellation Coma Berenices.

The Three Leaps asterism is formed by Alula Borealis and Alula Australis (the First Leap), Tania Borealis and Tania Australis (the Second Leap), and Talitha and Alkaphrah (the Third Leap). These stars lie halfway between the Big Dipper and the constellation figure of Leo.

Messier 40 (M40, Winnecke 4, WNC 4)

Winnecke 4 is a double star in Ursa Major. It was originally catalogued as a Messier object by Charles Messier in 1764, while he was looking for a nebula that Johann Hevelius reported seeing in the region. Not finding the nebula, Messier catalogued the binary star instead.

The German astronomer Friedrich August Theodor Winnecke rediscovered the visual double star in 1863 and included it in his Winnecke Catalogue of Double Stars of 1869.

The two stars of Messier 40 appear in the same field of view but are unrelated. One is an orange giant of the spectral type K0 III, located 1,013 light-years away, and the other is a yellow dwarf with the stellar classification G0 V that lies at less than half the distance, 470 light years away. The stars have apparent magnitudes of 9.64 and 10.11.

Broken Engagement Ring

The Broken Engagement Ring is a telescopic asterism about a degree west of Merak. It is a semi-circle of stars about 15 arcminutes across, with a magnitude 7.4 star appearing as the diamond.

Eiffel Tower

The Eiffel Tower is a faint asterism in the region of the Big Dipper’s handle. It forms a triangle with Alioth and Mizar. The star pattern resembles the famous landmark and is about 28 arcminutes across. It is also known as Ferrero 6, after its discoverer, the French amateur astronomer Laurent Ferrero.

Stars

Ursa Major is one of the brighter northern constellations. It does not contain any first magnitude stars, but its six brightest stars shine at second magnitude and are easily visible even from light-polluted areas. They are part of the Big Dipper.

Most bright stars in the constellation of Ursa Major are members of the Ursa Major Moving Group. Also known as the Ursa Major association and Collinder 285, the stellar grouping is the nearest moving group to the Sun. The members include Big Dipper stars Alioth, Mizar, Phecda, Merak and Mizar. These stars share common velocities in space and are believed to have a common origin.

The Ursa Major Moving Group was discovered by the English astronomer Richard A. Proctor in 1869. Proctor realized that all stars of the Big Dipper with the exception of Alkaid and Dubhe have proper motions heading toward a common point in the constellation Sagittarius. The stars Alphecca (Alpha Coronae Borealis), Menkalinan (Beta Aurigae), Skat (Delta Aquarii), Gamma Leporis and Zhou (Beta Serpentis) are outlying members of the group.

Alioth, the brightest star in Ursa Major, has the Bayer designation Epsilon Ursae Majoris, while the slightly fainter Dubhe has the designation Alpha Ursae Majoris. German astronomer Johann Bayer, who assigned the Greek letter designations to 1,564 stars in his star atlas Uranometria (1603), was guided by the order of magnitude and not by individual brightness. In the case of Ursa Major, he assigned the Greek letters going from west to east. He designated the Pointer Stars Dubhe and Merak Alpha and Beta because they are the westernmost second magnitude stars in the constellation. Alioth lies in the Big Dipper’s handle, to the east, and was given the designation Epsilon.

Alioth – ε Ursae Majoris (Epsilon Ursae Majoris)

Alioth (ε UMa) is an evolved star located 82.6 light-years away. With an apparent magnitude of 1.77, it is the brightest star in Ursa Major and, on average, the 32nd brightest star in the sky. It is the star in the Great Bear’s tail that is the closest to the Bear’s body.

Alioth has the spectral type A1III-IVp kB9, indicating a chemically peculiar blue-white giant or subgiant star. Even though it is a relatively young star, with an estimated age of 300 million years, Alioth has burned through its supply of hydrogen fuel and evolved away from the main sequence. It has 2.91 times the Sun’s mass and a radius 4.29 times that of the Sun. With an effective temperature of 8,908 K, it is 104.4 times more luminous than the Sun.

Alioth is classified as an Alpha² Canum Venaticorum variable. Alpha² CVn stars are chemically peculiar stars with strong magnetic fields that show variations in brightness by 0.01 to 0.1 magnitudes, accompanied by changes in their spectral lines and magnetic fields. The brightness variations are believed to be caused by an uneven distribution of elements in the stars’ atmospheres, resulting in spots that come in and out of view as the stars spin. Alioth exhibits fluctuations in its spectral lines with a period of 5.1 days.

The star’s traditional name comes from the Arabic phrase alyat al-hamal, meaning “the fat tail of a sheep.”

Dubhe – α Ursae Majoris (Alpha Ursae Majoris)

Dubhe (α UMa) is an orange giant star located approximately 123 light-years away. With an apparent magnitude of 1.79, it is the second brightest star in Ursa Major and the 34th brightest star in the sky. To the unaided eye, it appears as bright as Alioth. Unlike Alioth, Dubhe does not belong to the Ursa Major Moving Group.

The name Dubhe comes from the Arabic dubb, meaning “bear.” It is taken from the phrase żahr ad-dubb al-akbar, “the back of the Greater Bear.”

Dubhe has a mass of 3.7 solar masses and a radius of 26.85 solar radii. With a surface temperature of 4,650 K, it has an energy output of 339 Suns. It has an estimated age of 280 million years.

Dubhe has a fainter spectroscopic companion, Alpha Ursae Majoris B. The companion is a blue-white main sequence star of the spectral type A5V. It has a mass 2.5 times that of the Sun.

The two stars have an orbital period of 44.45 years. They are separated by only 0.590 arcseconds in the sky, corresponding to a physical separation of about 23 astronomical units (AU). The pair cannot be resolved even in the largest of telescopes.

Dubhe and its close companion form a quadruple star system with another spectroscopic binary star at an angular separation of 7.1 arcminutes, or about 90,000 AU away from the main pair. The component Alpha Ursae Majoris C shines at 7th magnitude. Its individual components orbit each other with a period of 6.035 days.

Alkaid – η Ursae Majoris (Eta Ursae Majoris)

Alkaid (η UMa) is a hot blue main sequence star of the spectral type B3 V. It shines at magnitude 1.86 from a distance of 103.9 light-years. It is the third brightest star in Ursa Major and the 38th brightest star in the sky.

Alkaid is the easternmost star in the Big Dipper asterism. It marks the end of the Dipper’s handle and the tip of the Great Bear’s tail. Like Dubhe, it does not belong to the Ursa Major stellar family. The luminous star is much younger than other Big Dipper stars. It has an estimated age of only 10 million years. However, it will evolve much faster than its bright neighbours due to its high mass (6.1 solar masses).

Alkaid has a surface temperature of 15,540 K and shines with 594 solar luminosities. It is a very fast spinner, with a projected rotational velocity of 150 km/s.

Alkaid was traditionally also known as Elkeid and Benetnasch (or Benetnash). Both traditional names come from the Arabic phrase qā’id bināt na’sh, meaning “the leader of the daughters of the bier.” In Arabic lore, the three stars marking the handle of the Big Dipper represented three mourning maidens, while the stars that form the body of the bowl represented the bier. The name Alkaid itself means leader.

Mizar – ζ Ursae Majoris (Zeta Ursae Majoris)

Mizar (ζ UMa) is the primary component in a quadruple star system located 82.9 light years away. It is the middle star in the handle of the Big Dipper. With an apparent magnitude of 2.04, it is the fourth brightest star in the Great Bear. Mizar forms a visual double star with the fainter Alcor (a binary system) and the two may form a sextuple star system.

Zeta Ursae Majoris consists of two pairs of spectroscopic binary stars separated by 14.4 seconds of arc in the sky. The system has a combined apparent magnitude of 2.04. The components Zeta¹ Ursae Majoris and Zeta² Ursae Majoris shine at magnitudes 2.23 and 3.88.

Zeta¹ Ursae Majoris is composed of nearly identical stars of the spectral type A2Vp. The components are Ap stars, chemically peculiar stars with strong lines of strontium and silicon.

Both stars have a mass of around 2.2 solar masses and radii 2.4 times that of the Sun. They are around 370 million years old and have effective temperatures of 9,000 K. Both components have luminosities of 33.3 Suns. They orbit each other with a period of 20.5386 days and are separated by only 9.83 milliarcseconds in the sky.

Zeta² Ursae Majoris is a single-lined spectroscopic binary system with an orbital period of around 176 days. The system has the combined spectral type kA1h(eA)mA7IV-V, with the luminosity class between main sequence and subgiant. The primary component has a mass of 1.85 solar masses and a radius 1.8 times that of the Sun. The secondary component is considerably less massive, with a mass of only 0.25 solar masses.

The name Mizar is derived from the Arabic mīzar, which means “girdle” or “waistband.”

Mizar was the first double star ever to be photographed. The early American photographer and inventor John A. Whipple and astronomer George P. Bond took the photo of the binary system in 1857 using a wet collodion plate and the 15-inch refractor telescope at Harvard College Observatory. Bond had previously also photographed the star Vega in the Lyra constellation in 1850.

Mizar A was the first star to be identified as a spectroscopic binary system. American astronomer Antonia Maury, one of the Harvard Computers, determined the system’s orbit based on the periodic doubling of some of its spectral lines in 1890.

Alcor (80 Ursae Majoris)

Alcor (80 UMa) is a binary star composed of a white main sequence star and a red dwarf. The star system lies 81.7 light years away and shines at magnitude 3.99. The name Alcor comes from the Arabic al-khawāri, meaning “the faint one.”

Alcor is a visual companion to the brighter Mizar in the sky. The two stars are sometimes known as the Horse and Rider. They are separated by about 12 arcminutes and appear as a visual pair to the unaided eye. Both stars are members of the Ursa Major Moving Group and share a common proper motion. However, it is not certain that they are gravitationally bound to each other because the stars’ exact distances from Earth are not completely certain.

Astronomers believe that the physical separation between the two star systems is 74,000 ± 39,000 AU, or 0.5 – 1.5 light-years. If, however, they lie at the same distance from the Sun, then the distance between them is 17,800 AU, or only 0.281 light-years.

Alcor, the primary component in the 80 Ursae Majoris system, has the spectral class A5Vn. It has a mass of 1.842 solar masses and is about 14 times more luminous than the Sun. It has an estimated age of 422 million years.

Alcor is an exceptionally fast spinner. It has a projected rotational velocity of 239 km/s. As a result, it has an oblate shape. It has an equatorial radius of 2.002 solar radii and a polar radius of 1.723 solar radii. Since the star’s poles are closer to the centre of mass, they are hotter than the equator. The star has an equatorial temperature of 7,556 K and a polar temperature of 8,985 K.

The companion, Alcor B, is a red dwarf of the spectral type M3-4. It has only 25% of the Sun’s mass and is believed to be around 500 million years old. It was discovered in 2009. The dim star has an apparent magnitude of 8.8.

Alcor was historically also known as Saidak (“true”), Al Sadak (“the test”), and Suha or Suhā/Sohā (“the forgotten one” or “the neglected one”). In Hindu mythology, it was associated with Arundhati, the wife of the Sage Vashishta (Mizar).

Merak – β Ursae Majoris (Beta Ursae Majoris)

Merak (β UMa) is a white subgiant star located 79.7 light years away. With an apparent magnitude of 2.37, it is the fifth brightest star in Ursa Major. The name Merak comes from the Arabic al-maraqq, meaning “the loins.”

Merak has the spectral type A1IVps. It is mild Am star, a chemically peculiar metallic-line star with prominent lines of heavier elements. It has a mass of 2.56 solar masses and a radius 2.81 times that of the Sun. The star is 63.5 times more luminous than the Sun, with an effective temperature of 9,700 K. It is believed to be around 390 million years old.

Merak shows an excess emission in the infrared, indicating that it has an orbiting circumstellar debris disk. The dust disk orbits at 47 AU from the star. It has a temperature of 120 K and a mass 0.27 percent that of the Earth.

The slightly fainter Phecda, the other star at the base of the Big Dipper’s bowl, is one of Merak’s closest neighbours. They are separated by only 11 light years. 37 Ursae Majoris is even closer to Merak, at a distance of 5.2 light-years.

Phecda – γ Ursae Majoris (Gamma Ursae Majoris)

Phecda (γ UMa) is a white main sequence star of the spectral type A0 Ve. It shines at magnitude 2.438 from a distance of 83.2 light-years. It is the lower left star in the bowl of the Big Dipper

Phecda forms a binary system with a fainter orange main sequence star with the spectral class K2 V. The two stars take 20.5 years to complete an orbit around the common centre of mass. They are separated by only 0.460 arcseconds in the sky.

Phecda has 2.412 times the Sun’s mass and is 44.57 times more luminous than the Sun. It is an Ae star, surrounded by an envelope of expelled gas that is adding emission lines to its spectrum. It is ejecting material because of its exceptionally high spin rate (184.5 km/s). The star has an estimated age of 333 million years.

Fast rotation is also responsible for the star’s oblate shape. Like Alcor, Phecda is an example of gravity darkening. Because of its flattened shape, its poles are closer to the centre of mass and therefore hotter and brighter than the equatorial region. The star has a polar radius of 2.186 solar radii and an equatorial radius of 3.385 solar radii, and a temperature of 10,520 K at the poles and 6,751 at the equator.

The companion, Gamma Ursae Majoris B, has 79% of the Sun’s mass and shines with 39.7% of the Sun’s luminosity. It is much cooler than Gamma Ursae Majoris A, with a surface temperature of 4,780 K.

The star’s traditional name, Phecda (or Phad), is derived from the Arabic phrase fakhð ad-dubb, meaning “the thigh of the bear.”

Phecda is located only 8.55 light years away from the Mizar-Alcor star system.

Ψ Ursae Majoris (Psi Ursae Majoris)

Psi Ursae Majoris (ψ UMa) is an orange giant of the spectral type K1 III. It lies at a distance of 140 light-years and has an apparent magnitude of 3.01. It appears in one of the Great Bear’s legs. In Chinese astronomy, it is known as Tien Tsan or Ta Tsun, meaning “exceptionally honourable.” Even though it is a relatively bright star, Psi UMa does not have a formal name approved by the International Astronomical Union (IAU).

The star has a mass of 2.31 solar masses and a radius of 19.12 to 20.79 solar radii. With an effective temperature of 4,543 K, it is 140 times more luminous than the Sun.

Tania Australis – μ Ursae Majoris (Mu Ursae Majoris)

Tania Australis (μ UMa) is the primary component in a binary star system located 230 light-years from Earth. The system has an apparent magnitude of 3.06.

The Mu Ursae Majoris system is composed of a red giant of the spectral type M0 IIIab and a fainter unseen companion. The two stars have an orbital period of 230.089 days and are separated by only 0.0028 arcseconds in the sky. At this separation, the individual components cannot be resolved even in the largest telescopes.

The primary component, Tania Australis, has a mass 6.3 times that of the Sun and radius 75 times the Sun’s. It is 977 – 1,200 times more luminous than our host star.

Tania Australis is a suspected variable star. Its brightness has been reported to vary between magnitude 2.99 and 3.33.

The companion has an estimated mass of 0.96 solar masses.

The name Tania Australis refers to the Three Leaps of the Gazelle asterism. It is derived from the Arabic Al Fiḳrah al Thānia, meaning “the second spring (of the gazelle).” Tania is Arabic for “second” and australis is Latin for “southern.” Mu Ursae Majoris is the southern of the two stars of the Second Leap of the Gazelle. The fainter Tania Borealis is the other half of the pair.

θ Ursae Majoris (Theta Ursae Majoris)

Theta Ursae Majoris (θ UMa) is a yellow-white subgiant star with the stellar classification F6 IV. It appears in the front leg of the Great Bear. It has an apparent magnitude of 3.7 and lies 43.96 light-years away.

The star has a mass of 1.41 solar masses and a radius of 2.41 solar radii. It shines with 7.871 solar luminosities and spins at 6.8 km/s. It has an estimated age of 2.2 billion years.

Theta Ursae Majoris may be the primary component in a triple star system. The presence of a spectroscopic companion was reported in 1976, but it remains disputed. The star also has a common proper motion companion at a separation of 4.1 arcseconds.

Talitha – ι Ursae Majoris (Iota Ursae Majoris)

Talitha (ι UMa) is the primary component in a multiple star system located 47.3 light-years away. The star system marks the celestial Bear’s front paw. It has an apparent magnitude of 3.14.

The Iota Ursae Majoris system is composed of two pairs of binary stars. The two binary systems orbit each other with a period of 2,084 years.

Talitha (Iota Ursae Majoris Aa) is the brightest component in the system. It is a white subgiant star of the spectral type A7V(n). It has a mass of 1.7 solar masses and a radius of 1.67 solar radii. With an effective temperature of 8,242 K, it shines with 8.98 solar luminosities. It has an estimated age of 620 million years.

Talitha has a spectroscopic companion, Iota Ursae Majoris Ab, which is believed to be a white dwarf with a mass similar to the Sun’s. The companion has not been directly observed.

The other binary system consists of a pair of red dwarfs, Iota Ursae Majoris C and Iota Ursae Majoris D, with masses of 0.35 and 0.30 solar masses and radii of 0.46 and 0.43 solar radii. The brighter component is a 9th magnitude star, invisible to the unaided eye, and the fainter shines at 10th magnitude. The red dwarfs take 39.7 years to complete an orbit and are separated by about 0.7 arcseconds, corresponding to a physical distance of at least 10 AU between the stars.

The name Talitha comes from the Arabic Al Ḳafzah al Thalitha, meaning “the third leap of the gazelle.” Talitha and the fainter Alkaphrah form the Third Leap of the Gazelle.

Megrez – δ Ursae Majoris (Delta Ursae Majoris)

Megrez (δ UMa) is a white main sequence star of the spectral type A3 V. With an apparent magnitude of 3.312, it is the faintest of the seven bright stars that form the Big Dipper asterism. Megrez lies 80.5 light-years away. It forms the inner part of the Big Dipper’s bowl with the brighter Phecda.

Megrez has a mass 2.062 times that of the Sun and is 23 times more luminous than the Sun. It is another fast spinner with an oblate shape. With a projected rotational velocity of 244.6 km/s, it takes only 3.1 hours to complete a rotation. The star has an estimated age of 414 million years.

Due to its fast rotation, Megrez has a flattened shape. It has a radius of 1.921 solar radii at the poles and 2.512 solar radii at the equator. The surface temperature of the star is higher at the poles (10,030 K) than it is at the equator (6,909 K).

Delta Ursae Majoris emits an excess of infrared radiation, which indicates the presence of an orbiting debris disk. The disk orbits at a distance of 16 astronomical units (AU) from the star.

The star’s name, Megrez, is derived from the Arabic word al-maghriz, which means “the base.” The name refers to the star’s position at the base of the Great Bear’s tail.

Muscida – ο Ursae Majoris (Omicron Ursae Majoris)

Muscida (ο UMa) is a yellow giant star of the spectral type G5III. It lies 182 light years away and has an apparent magnitude of 3.35. It marks the Great Bear’s nose or snout.

The star has 2.72 times the Sun’s mass and it expanded to a size of 13.84 solar radii as it evolved into a giant. It has an effective temperature of 5,242 K and a luminosity 116 times that of the Sun. The star is much younger than the Sun. It has an estimated age of only 360 million years. It evolved faster than the Sun because it is more massive.

Muscida has a fainter companion at a separation of 7.1 seconds of arc. The companion has an apparent magnitude of 15.2.

Muscida has a planet, Omicron Ursae Majoris b, discovered in 2012. The planet has a minimum mass of 4.1 Jupiter masses. It orbits Muscida with a period of 1,630 days at an orbital distance of 3.9 astronomical units (AU).

Muscida is a runaway star. It has a peculiar velocity of 35.5 km s-1 relative to nearby stars.

The star’s traditional name, Muscida, means “the muzzle” in Latin.

Tania Borealis – λ Ursae Majoris (Lambda Ursae Majoris)

Tania Borealis (λ UMa) is a subgiant star of the spectral type A2 IV. It shines at magnitude 3.45 from a distance of 138 light years. It has an estimated age of 380 million years.

The star has a mass of 2.11 solar masses and a radius 2.3 times that of the Sun. With a surface temperature of 9,247 K, it is 37 times more luminous than the Sun. It spins at 50 km/s.

The star’s traditional name, Tania Borealis, means “the Northern (star) of the Second (leap).”

Alula Borealis – ν Ursae Majoris (Nu Ursae Majoris)

Alula Borealis (ν UMa) is a binary star located 399 light years away. It has an apparent magnitude of 3.49. It is believed to be about 200 million years old.

The primary component, Nu Ursae Majoris A, is an orange giant of the spectral type K3 III. It has a mass of 3.82 solar masses and a radius 60 times that of the Sun. It is 1,242 times more luminous than our host star and has an effective temperature of 4,422 K.

The star has a much fainter companion, a yellow dwarf, at an angular separation of 7.1 arcseconds. The companion has an apparent magnitude of 10.1.

The star’s traditional name, Alula Borealis, is derived from the Arabic word al-Ūlā, which means “the first (leap),” and the Latin word for “northern,” borealis.

Alkaphrah – κ Ursae Majoris (Kappa Ursae Majoris)

Alkaphrah (κ UMa) is a double star located 358 light-years away. It has a combined apparent magnitude of 3.56. The individual components shine at magnitudes 4.16 and 4.54.

Both stars in the Kappa Ursae Majoris system are A-type stars. The primary component, Kappa UMa A, has the stellar classification A0 IV-V, indicating that it is coming to the end of its hydrogen fusing lifetime. The companion is still on the main sequence and has the spectral type A0 V.

The primary component has 3.79 times the Sun’s mass and a radius 7.87 times that of the Sun. It has a surface temperature of 9,060 K and is an exceptionally fast spinner, with a projected rotational velocity of 201 km/s. The star has a debris disk with a mean temperature of 165 K orbiting at a distance of 55.2 astronomical units.

The name Alkaphrah comes from the Arabic al-qafzah, meaning “the leap.”

Taiyangshou – χ Ursae Majoris (Chi Ursae Majoris)

Taiyangshou (χ UMa) is an orange giant star of the spectral type K0.5 IIIb. It shines at magnitude 3.72 from a distance of 198 light years. It has a mass of 1.49 solar masses and has expanded to a size of 23.15 solar radii as it evolved into a giant. It is 170.1 times more luminous than the Sun and has an effective temperature of 4,331 K.

Taiyangshou is the brightest point of light near the imaginary line connecting Phecda and Alula Borealis. The spiral galaxy NGC 3877 appears only 15 arcminutes south of the star.

The name Taiyangshou comes from the Chinese Tai Yang Shou (太陽守), meaning “the Sun Governor” or “Guard of the Sun.”

Alula Australis – ξ Ursae Majoris (Xi Ursae Majoris)

Alula Australis (ξ UMa) is a quintuple star system located 28.5 light-years away. It is the second closest quintuple system to the Sun, after V1054 Ophiuchi in the constellation Ophiuchus. The two visual components, Xi Ursae Majoris A and Xi Ursae Majoris B, have apparent magnitudes of 4.264 and 4.729.

Alula Australis was discovered to be a visual double star by the German-born British astronomer William Herschel in 1780. In 1828, French astronomer Félix Savary calculated the system’s orbit. This was the first star system for which an orbit was calculated.

The main components in the Xi Ursae Majoris system are yellow dwarfs of the spectral types F8.5:V and G2V. They orbit each other with a period of 59.878 years and are separated by 2.536 arcseconds in the sky.

Both components are themselves single-lined spectroscopic binary stars. The components Xi UMa Aa and Ab have an orbital period of 669 days, while Xi UMa Ba and Bb take only 3.98 days to complete an orbit around a common centre of mass. Xi UMa Ab is believed to be a red dwarf, and Xi UMa Bb either a red dwarf or a white dwarf.

The system has another companion, a brown dwarf, at a separation of 8.5 arcminutes, corresponding to a physical distance of around 4,000 astronomical units.

Xi Ursae Majoris is classified as an RS Canum Venaticorum variable. RS Canum Venaticorum variables are close binary stars with large stellar spots caused by the stars’ active chromospheres. In some cases, the fluctuations in brightness are caused by the stars being eclipsing binaries. The component Xi UMa B is believed to be the source of the variations. Its brightness varies by 0.01 magnitude.

The name Alula comes from the Arabic phrase Al Ḳafzah al Ūla, meaning “the first spring” or “the first leap.” The word itself means “the first.” Australis is Latin for “southern.”

Chalawan (47 Ursae Majoris)

Chalawan (47 UMa) is a yellow main sequence star located 45.30 light years away. It has the spectral type G1V. With an apparent magnitude of 5.03, the solar analog is faintly visible to the unaided eye. It appears in the region of the Great Bear’s feet.

The star is slightly larger and more massive than the Sun. It has a mass of 1.08 solar masses and a radius of 1.172 solar radii. With a surface temperature of 5,887 K, it shines with 1.48 solar luminosities.

Chalawan has about 110 percent of the Sun’s abundance of iron and is older than our parent star. It has an estimated age of 6.03 billion years.

47 Ursae Majoris hosts three orbiting planets. 47 Ursae Majoris b was detected in 1996. It was the first long-period planet to be discovered. It has a mass at least 2.53 times that of Jupiter and orbits 47 UMa with a period of 1,078 days (2.95 years).

The discovery of 47 Ursae Majoris c was announced in 2002. The planet has an orbital period of 2,391 days (6.55 years) and a mass of at least 0.540 Jupiter masses.

The third planet, 47 Ursae Majoris c, was discovered in 2010. It has a mass of at least 1.64 Jupiter masses and an orbital period of 14,002 days (38.33 years). It orbits Chalawan at a distance of 11.6 AU with an eccentricity of 0.16.

In 2015, the star 47 Ursae Majoris was named Chalawan, after a mythological crocodile from a Thai folktale. The planets 47 Ursae Majoris b and c were formally named Taphao Thong and Taphao Kaew, after two sisters from the same tale.

Intercrus (41 Lyncis)

Intercrus (41 Lyn) is an orange giant located approximately 276 light-years away. It appears in the area between the second and third leaps of the gazelle, near the border with the constellation Lynx. It has an apparent magnitude of 5.39.

41 Lyncis has the stellar classification K0 III. It has a mass 107% that of the Sun and a radius about 11 times the Sun’s. It shines with 60.30 solar luminosities with an effective temperature of 4,797 K. The evolved star is slightly younger than the Sun, with an estimated age of 4.07 billion years.

The star has the Bayer designation 41 Lyncis because it belonged to the constellation Lynx before the International Astronomical Union (IAU) established the constellation boundaries in 1930.

41 Lyncis hosts an orbiting exoplanet, 41 Lyncis b (HD 81688 b). The discovery of the planet was announced on February 19, 2008. 41 Lyncis b has a minimum mass of 2.7 Jupiter masses and orbits the host star with a period of 183.93 days.

41 Lyncis was named Intercrus in December 2015. The name means “between the legs” and refers to the star’s position in Ursa Major. The planet HD 81688 b was named Arkas, after the son of the nymph Callisto in Greek mythology.

HD 89744

HD 89744 is an old F-type star located 125.8 light-years away. It appears only 0.4 degrees south of the brighter Tania Australis (Mu Ursae Majoris). It has an apparent magnitude of 5.73.

HD 89744 is classified as a main sequence star or subgiant of the spectral type F7V or F8IV. It has an estimated age of 8.4 billion years. It has a mass of 1.37 solar masses and a radius 2.16 times that of the Sun. With a surface temperature of 6,381 K, the star is 6.38 times more luminous than the Sun. It spins at 9.3 km/s, taking around 9 days to complete a rotation.

HD 89744 has a brown dwarf companion with a mass of 0.076 solar masses at an angular separation of 63.1 arcseconds, corresponding to a distance of 2,456 astronomical units.

A planet was discovered orbiting the primary component in 2000. HD 89744 b has a mass of at least 8.35 Jupiter masses and an orbital period of around 257 days. It orbits at a separation of 0.917 astronomical units.

A second planet, HD 89744 c, was reported in 2019. The unconfirmed planet has a minimum mass of 5.36 Jupiter masses and orbits the star with a period of 6,974 days at a distance of 8.3 astronomical units.

Argelander’s Star (Groombridge 1830)

Groombridge 1830 is an orange main sequence star of the spectral type K1V Fe-1.5. It has an apparent magnitude of 6.44 and lies only 29.914 light years away.

When it was discovered, Groombridge 1830 was the star with the highest proper motion of any star known. It dropped to the third place after the discovery of Kapteyn’s Star in the constellation Pictor and Barnard’s Star in Ophiuchus.

Groombridge 1830 has a mass of 0.63 solar masses and a radius of 0.586 solar radii. It shines with 0.221 solar luminosities and has an effective temperature of 5,174 K. It has an estimated age between 4.7 and 5.3 billion years.

The star was catalogued by the British astronomer Stephen Groombridge in the early 19th century in his Catalogue of Circumpolar Stars, published posthumously in 1838.

Groombridge 1830 is also known as Argelander’s Star, after the German astronomer Friedrich Wilhelm Argelander, who noted its high proper motion in 1842.

Like Kapteyn’s Star, Groombridge 1830 is a halo star, one that appears to be moving in the direction opposite to the galaxy’s rotation because it does not follow the rotation of the Milky Way. Halo stars are typically metal-poor, because they formed when the galaxy was younger. Most halo stars are located either far above or below the galactic plane and believed to be at least 10 billion years old. They have highly eccentric orbits and high space velocities.

Lalande 21185

Lalande 21185 (Gliese 411) is a red dwarf located only 8.3044 light-years away. With an apparent magnitude of 7.5, it is below unaided eye visibility, but it is nonetheless the brightest red dwarf in the northern celestial hemisphere. The small red star appears in the region of the Great Bear’s hind legs, near Praecipua, the brightest star in Leo Minor.

Lalande 21185 is the fourth nearest star or star system and the sixth nearest individual true star to the Sun, after Proxima Centauri, Rigil Kentaurus and Toliman in the Alpha Centauri system in the constellation Centaurus, Barnard’s Star in Ophiuchus, and Wolf 359 in Leo. The brown dwarfs Luhman 16 A and B in Vela and WISE 0855−0714 in Hydra also lie closer to Earth.

Lalande 21185 lies only 0.3 light years closer to us than Sirius, the brightest star in the sky. It is catalogued as Gliese 411 (GJ 411) in the Gliese Catalogue of Nearby Stars.

The red dwarf star has only 38.9% of the Sun’s mass and 39.2% of the Sun’s radius. With a surface temperature of 3,547 kelvin, it has a bolometric luminosity of only 0.02194 solar luminosities and a visual luminosity 0.55% that of the Sun. Most of the star’s energy output is in the infrared part of the spectrum.

Lalande 21185 takes 56.15 days to complete a rotation. The star is much older than the Sun. It has an estimated age of 8.047 billion years.

Lalande 21185 is classified as a BY Draconis-type variable and is a known X-ray source. BY Draconis stars vary in brightness by up to 0.5 magnitudes due to chromospheric activity and starspots.

Three planets – one of them unconfirmed – have been reported to be orbiting the red dwarf. All three orbit outside of the star’s goldilocks zone. Lalande 21185 b has a mass of at least 2.69 Earth masses and orbits the star with a period of only 12.9394 days at a distance of 0.07879 astronomical units.

The unconfirmed planet Lalande 21185 d has a mass of at least 3.89 Earth masses and an orbital period of 215.7 days. It is separated by 0.5142 AU from the host star.

The outermost planet, Lalande 21185 c, has a mass of at least 13.8 Earth masses and orbits Lalande 21185 at a distance of 2.94 astronomical units, taking 2,946 days to complete an orbit.

W Ursae Majoris

W Ursae Majoris (W UMa) is a binary star system located 169.2 light years away. With a combined apparent magnitude of 7.90, the system is well below unaided eye visibility. The two individual components have apparent magnitudes of 7.75 and 8.48. They may have a 12th magnitude common proper motion companion.

W Ursae Majoris serves as the prototype for a class of variable stars called the W Ursae Majoris variables. These are low-mass contact binary stars that show variations in brightness because the components eclipse each other as they orbit. These stars share a common envelope of material and they transfer mass.

W Ursae Majoris A and W Ursae Majoris B are in a very tight orbit with a period of only 0.336 days (8 hours and 26 seconds). When the brighter primary component is eclipsed, the system’s brightness decreases by 0.73 magnitudes. When the primary component eclipses the fainter secondary star, the brightness drops by 0.68 magnitudes.

Both components of the W Ursae Majoris system are main sequence stars with the stellar classification F8Vp. The primary component has a mass of 1.139 solar masses and a radius of 1.092 solar radii. It is 1.557 times more luminous than the Sun.

The secondary component has less than half the mass (0.551 M_☉) and a radius of 0.792 solar radii. It shines with 0.978 solar luminosities.

Aniara (HD 102956)

HD 102956 is an orange subgiant star located approximately 399 light years from Earth. It has a mass of 1.68 solar masses and a radius 4.4 times that of the Sun. With a surface temperature of 5,054 K, it is 11.6 times more luminous than the Sun. The star has an estimated age of 2.3 billion years.

The evolved star was named Aniara during the 2019 NameExoWorlds campaign. Aniara is the name of a spaceship in the epic science fiction poem Aniara (1956) by Swedish author and Nobel laureate Harry Martinson.

Aniara hosts an orbiting exoplanet, HD 102956 b, formally named Isagel, after the fictional pilot of the Aniara spaceship. The planet was discovered in 2010. It has a mass of 1.23 Jupiter masses and a radius of 0.96 Jupiter radii. It orbits Aniara at a distance of 0.807 astronomical units, taking 6.5 days to complete an orbit.

Liesma (HD 118203)

HD 118203 is a yellow dwarf star of the spectral type G0V. It lies 300.2 light years away and has an apparent magnitude of 8.06.

HD 118203 is older, larger and more massive than the Sun. It has a mass of 1.353 solar masses and a radius of 1.993 solar radii. With a surface temperature of 5,872 K, it shines with 4.42 solar luminosities. The star is believed to be 5.4 billion years old. It spins at 7 km/s.

The name Liesma comes from the Latvian poem Staburags and Liesma and means “flame.”

An orbiting extrasolar planet, HD 118203 b, was reported in the HD 118203 system in 2006. The planet has a mass of around 2.173 Jupiter masses and a mean radius of 1.133 Jupiter radii. It has an equilibrium temperature of 26° C (46.8° F). It orbits the star at a distance of 0.7 astronomical units, taking 6.134 days to complete an orbit.

The planet HD 118203 b was formally named Staburags, after a character in the poem Staburags and Liesma.

A second planet orbiting HD 118203 was discovered in 2024. HD 118203 c has 11.1 times Jupiter’s mass and orbits the host star with a period of 5,070 days at a distance of 6.20 AU.

Násti (HD 68988)

HD 68988 is a yellow main sequence star of the spectral type G1 V. It lies approximately 197 light-years away and shines at magnitude 8.20. It is sometimes classified as a yellow subgiant.

The star has a mass of 1.16 solar masses and a radius 1.08 times that of the Sun. With a surface temperature of 5,919 K, it shines with 1.297 solar luminosities. It spins at 6.4 km/s and has an estimated age of around 1 billion years.

The name Násti comes from the Northern Sami language and means “star.”

HD 68988 hosts two exoplanets, discovered in October 2001 and November 2006. HD 68988 b is a hot Jupiter with a mass of at least 1.86 Jupiter masses and an orbital period of 6.27711 days. It orbits the parent star at a distance of 0.0704 AU. The gas giant is formally named Albmi. The name means “sky” in the Sami language.

The more distant HD 68988 c has around 15 times the mass of Jupiter and orbits HD 68988 with a period of 16,100 days at a distance of 13.2 AU.

HIP 57274

HIP 57274 is an orange dwarf of the spectral type K5 V. It has an apparent magnitude of 8.96 and lies at an approximate distance of 84.4 light-years from Earth. The star is much older than the Sun, with an estimated age of 7.87 billion years.

HIP 57274 has only 73% of the Sun’s mass and shines with 68% of the Sun’s luminosity. It has a radius of 0.68 solar radii and spins very slowly, at 0.5 km/s. It takes 45 days to complete a rotation.

HIP 57274 hosts a planetary system, discovered in 2011. All three planets are much more massive than Earth and none of them orbit in the host star’s habitable zone.

The innermost known planet, HD 57274 b, has a mass of at least 11.6 Earth masses and an orbital period of 8.1352 days. It orbits the parent star at a distance of only 0.0713 AU.

HD 57274 c has a mass of more than 0.41 Jupiter masses an orbital period of 32.03 days. It lies at an orbital distance of 0.1778 AU from HD 57274.

The outermost planet, HD 57274 d, has a mass of at least 0.527 Jupiter masses (167 Earth masses). The gas giant planet orbits the star with a period of 431.7 days at a distance of 1.007 AU, which is almost equivalent to Earth’s average orbital distance from the Sun.

Mazalaai (HAT-P-21)

HAT-P-21 is a yellow dwarf with the spectral class G3V. It shines at magnitude 11.46 from a distance of 927 light years. The star has an orbiting exoplanet, HAT-P-21b, discovered in 2010.

HAT-P-21 has a mass of 0.947 solar masses and a radius of 1.105 solar radii. With a surface temperature of 5,634 K, it shines with 1.06 solar luminosities. The star is much older than the Sun. It has an estimated age of 10.2 billion years.

The hot super-Jovian planet orbiting HAT-P-21 has a mass of 4.063 Jupiter masses and a radius of 1.08 Jupiter radii. It orbits the host star with a period of 4.124481 days at a distance of 0.0494 astronomical units, or about 5% of the average distance between the Earth and the Sun.

The star HAT-P-21 was given the name Mazalaai and the planet HAT-P-21b was named Bambaruush during the 2019 IAU NameExoWorlds campaign. Mazalaai is the Mongolian name for the endangered Gobi bear subspecies and Bambaruush is the Mongolian word for “bear cub.”

Dombay (HAT-P-3)

HAT-P-3 is an orange dwarf of the spectral type K5 V. It lies 439.8 light-years away and has an apparent magnitude of 11.577, well below unaided eye visibility. The star is smaller and less massive than the Sun, with a mass of 0.925 solar masses and a radius of 0.850 solar radii. It has an estimated age of only 2.9 million years.

HAT-P-3 hosts an extrasolar planet, HAT-P-3b, discovered in 2007. The planet has a mass of 0.609 Jupiter masses and a radius 89% that of Jupiter. It orbits the parent star at a distance of 0.03899 astronomical units and takes 2.8997360 ± 0.0000020 days to complete an orbit.

In 2019, the star was named Dombay, after a resort region in the North Caucasus mountains known for its rich wildlife, including bears. The planet was named Teberda, after a river in the Dombay region.

US 708

US 708 is one of the fastest moving stars in the Milky Way galaxy. It is a class O subdwarf located 60,300 light-years away. With an apparent magnitude of 18.8, it is well below unaided eye visibility.

The hypervelocity star was discovered by a team led by Peter Usher at Pennsylvania State University in 1982.

In 2015, a team of astronomers led by Stephan Geier of the European Southern Observatory (ESO) reported that the star was moving with a velocity of 1,200 km/s. This exceeds the escape velocity of the Milky Way. However, it does not make US 708 the fastest known star. The A-type star S5-HVS1 in the constellation Grus is the record-holder, with a velocity of 1,755 km/s.

US 708 was once believed to have come from the Milky Way’s centre and that its speed could be attributed to our galaxy’s central black hole.

However, more recent studies have found that the star did not come from the Galactic centre. Astronomers now believe that it was ejected from a binary system by a supernova. It likely had a white dwarf companion when it reached its red giant phase. The white dwarf was accreting mass and, when it reached the critical mass of 1.44 solar masses, it went out as a type Ia supernova. The supernova event flung US 708 at its high velocity.

Deep sky objects in Ursa Major

Ursa Major is best-known for its many bright galaxies. Even though it is the third largest constellation in the sky, it does not have any particularly bright star clusters or diffuse nebulae.

Ursa Major contains seven objects listed in the Messier catalogue. One of these, Messier 40, is an optical double star. Of the remaining six objects, one is the planetary nebula Messier 97 – the famous Owl Nebula – and the others are galaxies. All five Messier galaxies in Ursa Major – Bode’s Galaxy (M81), the Cigar Galaxy (M82), the Pinwheel Galaxy (M101), the Surfboard Galaxy (M108), and M109 – can be found using the bright stars of the Big Dipper.

The Great Bear constellation does not contain any Caldwell objects, but it is home to as many as 46 deep sky objects listed in the Herschel 400 catalogue. All of them are galaxies. Only the constellation Virgo, the home of the Virgo Cluster, contains more objects included on the Herschel 400 observing list. Deep sky objects listed in the Messier, Caldwell and Herschel 400 catalogues can be observed in amateur telescopes.

Bode’s Galaxy – Messier 81 (M81, NGC 3031)

Messier 81 is a bright, large spiral galaxy about 11.8 million light years distant from Earth. Because of its relative proximity and brightness – it has an apparent magnitude of 6.94 – M81 is a popular target both for beginners and professional astronomers. The galaxy’s apparent size is 26.9 x 14.1 arc minutes. Only one supernova has been discovered in it: SN 1993J, in March 1993.

Bode’s Galaxy was discovered by the German astronomer Johann Elert Bode in 1774. In 1779, Charles Messier identified the galaxy independently and included it in his catalogue.

Bode’s Galaxy is the largest of the 34 galaxies in the M81 Group, one of the groups of galaxies located in Ursa Major. The galaxy can be seen about 10 degrees northwest of the star Dubhe (Alpha Ursae Majoris).

Bode’s Galaxy interacts with the nearby galaxies Messier 82 and the smaller NGC 3077. As a result of the interactions between the galaxies, hydrogen gas has been stripped away from all three and gaseous filamentary structures have formed in the group. Another consequence of the gravitational interactions is the vigorous star forming activity caused by interstellar gas falling into the centres of Messer 82 and NGC 3077.

Cigar Galaxy – Messier 82 (M82, NGC 3034)

Messier 82 is an edge-on starburst galaxy about 11.5 million light years from the solar system. It has an apparent magnitude of 8.41.

Star formation that occurs in the galaxy’s core is ten times faster than star forming activity in the entire Milky Way. M82 is also about five times brighter than our galaxy. 197 massive star clusters were discovered by Hubble in the galaxy’s central region in 2005.

M82 emits an infrared excess and is the brightest galaxy in the sky when observed in infrared light.

The Cigar Galaxy is believed to have had at least one tidal encounter with the neighbouring Messier 81 and, as a result, a large amount of gas ended up funneled into its core in the last 200 million years. Consequently, star forming activity in the galaxy has increased tenfold compared to most other galaxies.

M82 was discovered by Johann Elert Bode on December 31, 1774, along with M81. Bode originally described them both as nebulous patches.

Owl Nebula – Messier 97 (M97, NGC 3587)

The Owl Nebula is a planetary nebula about 2,600 light years away from the solar system. It has an apparent magnitude of 9.9. The nebula was first discovered by the French astronomer Pierre Méchain in 1781. It is believed to have formed about 8,000 years ago.

The Owl Nebula has a 16th magnitude star at its centre. It got its name because of its appearance of owl-like eyes when observed through a large telescope.

Pinwheel Galaxy – Messier 101 (M101, NGC 5457)

The Pinwheel Galaxy is a grand design spiral galaxy seen face-on. It has an apparent magnitude of 7.86 and is 20.9 million light years distant from Earth. It was discovered by Pierre Méchain in 1781 and Charles Messier subsequently included it in his catalogue. It was among the last entries.

A type Ia supernova, designated as SN 2011fe, was observed in the galaxy in August 2011.

Pierre Méchain described Messier 101 as a “nebula without star, very obscure and pretty large, 6′ to 7′ in diameter, between the left hand of Boötes and the tail of the great Bear. It is difficult to distinguish when one lits the [grating] wires.”

The Pinwheel Galaxy is about 170,000 light years in diameter, which makes it about 70 percent larger than the Milky Way galaxy. It contains a number of large, bright H II regions, full of bright, hot newly formed stars.

M101 has five notable companion galaxies: NGC 5474, NGC 5204, NGC 5477, NGC 5585 and Holmberg IV. The grand design pattern of the Pinwheel Galaxy is suspected to be a result of the interaction between the galaxy and its companions.

Messier 108 (M108, NGC 3556)

Messier 108 is a barred spiral galaxy, discovered by Pierre Méchain in 1781. From our perspective, the galaxy appears nearly edge-on.

M108 is an isolated member of the Ursa Major Cluster, a galaxy cluster within the Virgo Supercluster. M108 contains about 290 globular clusters and 83 X-ray sources.

The galaxy has a visual magnitude of 10.7 and is approximately 45,000 light years distant. A type 2 supernova, 1969B, was observed in M108 in 1969.

Messier 109 (M109, NGC 3992)

Messier 109 is another barred spiral galaxy in Ursa Major. It is located southeast of the star Phecda (Gamma Ursae Majoris). The galaxy has an apparent magnitude of 10.6 and is 83.5 million light years distant.

Like the other notable galaxies in Ursa Major, M109 was discovered by Pierre Méchain in 1781. Charles Messier included it in his catalogue two years later.

A type Ia supernova, SN 1956A, was seen in the galaxy in 1956. So far it has been the only supernova observed in M109.

M109 has at least three satellite galaxies, UGC 6923, UGC 6940 and UGC 6969. It is the brightest galaxy in the M109 Group, a large group consisting of more than 50 galaxies in Ursa Major.

NGC 5474

NGC 5474 is a peculiar dwarf galaxy in Ursa Major, located near the Pinwheel Galaxy (M101), with which it interacts. The galaxy is often classified as a dwarf spiral galaxy because it shows signs of a spiral structure. As a result of the tidal interactions with M101, the galaxy’s disk is offset from the nucleus, and so is the star formation.

NGC 5474 is the closest companion to M101. It has a visual magnitude of 11.3 and is approximately 22 million light years distant from the solar system.

Helix Galaxy (NGC 2685)

The Helix Galaxy is a lenticular polar ring galaxy located 48.2 million light-years away. It has an apparent magnitude of 11.3 and appears near Muscida (Omicron UMa), in the region of the Great Bear’s head. It is one of the nearest polar ring galaxies to the Sun. The galaxy was discovered by the German astronomer Wilhelm Tempel on August 18, 1882.