Walk through the sky of the circumpolar boreal region
This second tour is centered in part of the constellations of Ursa Major and Ursa Minor, which have a lot of interesting objects to observe, as well as the constellations of Cepheus, Cassiopeia and part of Perseus. Visible all year round from the northern hemisphere. It is not visible south of latitude 10ºS.
In Greek mythology, the two bears are the beautiful Callisto and her son Árcade, whom Hera transformed into bears in a fit of jealousy. Hera’s husband and Calisto’s lover, Zeus, the king of the gods, made them immortal and placed them in the heavens.
Cassiopeia was the wife of King Cepheus and mother of Andromeda. Cepheus and Cassiopeia consulted an oracle that told them that to appease the god of the sea they had to offer their daughter Andromeda as a sacrifice, so they chained her to a rock in the sea to be killed by Ceto, the sea monster. But Perseus fell in love with Andromeda and defeated the monster. Finally Perseus and Andromeda got married.
By placing the pointer over the image you can magnify it with the magnifying glass. With the mouse wheel you can enlarge or decrease the size of the magnifying glass field.
Let’s see some of the objects visible in this area.
1 Polar Star (Polaris, α Ursae Minoris). It is a Cepheid variable 46 times greater than the Sun and is at a distance of 432 light years. Visible to the naked eye, although with a telescope you can see a weak companion (mag.9) and a blue color at about 18 seconds of the Polar arc.
2 Mizar and Alcor (ζ and 80 Ursae Majoris). Of the three stars that form the car’s pole, Mizar is the central one. To the naked eye you can see a weak star just above it. It’s Alcor. With prismatic we can separate them easily, and with telescope we will see that Mizar has another companion of magnitude 4. It is Mizar B and is 14 seconds of arc.
3 Double Perseus Cluster (NGC 884 and NGC 869). This magnificent conglomeration of bright stars is known since ancient times. Because of their size, these two 100-member clusters of mids are best seen with binoculars or with a wide-field eyepiece.
4 M103 (NGC 581). At 1 degree northeast of Ruchbah we find M103. It was discovered by Pierre Méchain in 1781. The brightest stars of the cluster of magnitude 6.2 seem to trace the tip of an arrow. With a 100 mm telescope you can resolve many of the weakest stars, some of beautiful colors. Perhaps M103 is not a group of stars united by gravity, but simply a group of about 60 stars that appear as a cluster scattered from our point of view.
5 M52 (NGC 754). About 6 degrees northwest of NGC 7789 is this beautiful open star cluster. The 200 members of this cluster are located on the western edge of Cassiopeia. There is a thin row of stars that extend like an arm in an east-west direction through the cluster that are a good test for telescopes of 100 mm or more. In areas like this, replete with objects relatively easy to see with binoculars, it is a pleasure to wander around the many open clusters.
6 M81 (NGC3031) and M82 (NGC 3034). Drawing a line from γ to & alpha; Ursae Majoris and extending it to the north, these two galaxies are found. With binoculars are visible as two small cottony spots. With a telescope, the spiral M81 appears as an elliptical glow, while the irregular M82 is shaped like a cigar.
7 M108 (NGC 3556) and M97 (NGC3587), Lechuza nebula. They are below the Cart’s box, near β Ursae Majoris, or Merak. M87 is a planetary, the envelope that ejected an old star. The M108 galaxy is within walking distance. It is a spiral galaxy seen from the edge, with a milky white profile that appears flattened, with no trace of the central protuberance of most other spiral galaxies. With a magnitude of 10.1, M108 has a mottled texture with about four bright spots that can be seen on the arms. With a 250 mm telescope, there is an elongated band of dust that runs along the long axis of the galaxy.
8 NGC 188. It is the open cluster more north of the sky. It is located at 4º of Polaris towards γ Cassiopeiae and has a magnitude of 8.1. In a 6-inch telescope it appears as a great glow of 14 arc munutos with some brighter stars of magnitude 8 to 10, brighter around the western edge. An 8-inch sample shows that it has a granular texture, which illuminates smoothly towards its core. It is well above the plane of the Milky Way. Here, the forces of gravitational tides that attract open clusters are reduced and have allowed this cluster to remain together for 6.8 billion years.
9 IC 3568. It is a planetary nebula in the constellation of Camelopardalis. Also called Lemon Slice Nebula for the images that Hubble sent. It has a remarkably simple spherical shape. It has a magnitude of 10.7 and a diameter of 18 “. A 12-inch telescope shows a weaker outer ring surrounding a brighter core 10 “in diameter. It is located about two fifths of the distance between Polaris and Kappa Draconis.
10 M101 (NGC 5457). The Molinillo Galaxy. This beautiful spiral galaxy is located 5 degrees east of Mizar and Alcor. It is one of the largest and most beautiful front spirals that can be seen and, although it is quite luminous, around magnitude 9, it is also diffusive, so it is difficult to locate even with a 250 mm telescope. A dark sky and few increases with wide field is the best way to detect the knotty arms that extend from the nucleus. It was discovered by Pierre Méchain in 1781.
11 NGC 654, NGC 663 and NGC 659. About half a degree northwest of Ruchbach, within the same field of binoculars or finder, is an accumulation of open clusters in the form of U: NGC 654, NGC 663 and NGC 659. NGC 654 consists of 60 stars in loose association, but it is very easy to see with binoculars and appears as a diffuse glow of small and weak stars. NGC 663 is half grando south of NGC 654. It has a rounded appearance, similar to a mixture of open and globular cumulus if we look at it with 150 mm telescope. It has about 80 stars. Finally, NGC 659 is half a degree southwest of NGC 663. It is an X-shaped cluster formed by about 40 stars. Near it is the yellow-gold double star of magnitude 5.8, 44 Cassiopeiae, which is not a member of the cluster.
12 Caph (β Cassiopeiae). This double star and pulsating variable of short period is of a rare type called Delta Scuti. It is very difficult to detect its variability visually because its magnitude of 2.2 fluctuates very slightly during its cycle is only 2 hours long.
13 NGC 7789. Four degrees southwest of Caph we find this broad open cluster. It is quite large and lies between the semi-regular yellow variable 7 Rho (ρ) Cassiopeiae and the broad white multiple-star system 8 Sigma (σ) Cassiopeaiae. It can be seen very well with binoculars or a wide field eyepiece because it covers an area of the apparent size of the Moon.
14 Delta (δ) Cephei. With telescope we can solve this double star formed by a pale orange component and a blue one. The yellow star is the prototype of the Cepheid variables, yellow supergiants whose sizes and brightness pulsate regularly.
15 Mu (μ) Cephei, garnet star of Herschel. This cold supergiant star is so big that if it were placed in the place of the Sun, it would eat Jupiter. It is one of the reddest stars in the sky that can be observed with small telescopes.