Ambiguous constellations in the northern celestial sphere
synonymFox(located in the constellation south of Cygnus, north of Sagittarius and Dolphin) generally refers to the constellation Fox
FoxyIs a fuzzy constellation located in the northern celestial sphereCygnusto the south of,SagittariusAndDolphinTo the north, the brightest star is Alpha Fox (apparent magnitude 4.44), and the best observation month is September.There is a famous M27 planetary nebula in the constellation Fox, which is shaped like a dumbbell joined by two conical tops, so it is called“Dumbbell Nebula”, easy to observe in the night sky.[1]
This faint constellation is located inthe galaxyA bright area, so it is more difficult to observe.1660 Polish astronomerHaveliusI feel that there should be a constellation here.Although this area looks inconspicuous, useBinocularsOr a small telescope can find that this is an interesting sky area.Here is oneMessier object M27。
M27(NGC6853) Planetary nebula isFoxThe most famousdeep space 。M27's spherically expanding gas is not uniform and becomes very thin in the east-west direction, resembling a dumbbell, so it is also called the "dumbbell nebula".On July 12, 1764,messier Found it.M27 is bright and clear in structure, and is one of the good targets for small telescopes.
M27 Dumbbell Nebula in Foxy
All dayPlanetary nebulaThe Dumbbell Nebula in the constellation Fox is undoubtedly the most beautiful one. It is listed inMessier cluster nebula catalogueIt is also called M27 nebula.Because the larger planetary nebulae are relatively dark, and the brightest planetary nebulae are very small, the Dumbbell Nebula in the constellation Fox becomes the most easily observed planetary nebula.FoxyDumbbell NebulaIt is a very beautiful celestial body.Very bright, the apparent star magnitude is 7.6.Is all over the placefixed starIt is still prominent in the background of the stars, and its shape is like a dumbbell butt jointed by two conical tops, so it is called the "dumbbell nebula".Its equatorial coordinates are: 19:59.6 right ascension,+22 ° 43 ′ declination.The angular size is 8 ′. 0 × 5 ′. 7, the apparent magnitude is 7.3, and the distance is 815 light-years.
On July 12, 1764, when French astronomer Messier first observed it, he described that a cloud shaped object without stars could be easily observed with a 3.5 inch telescope, which was oval in shape, without any stars.It is not time to come again. Planetary nebulae generally have a core star. The core star of M27 is a star of Grade 12. This star has a continuous spectrum, that is, there are no bright and dark spectral lines in the spectrum.The nebula photos taken at different wavelengths of the spectrum show that in some cases it has a granular structure, and in other cases it can be seen to have a fine fibrous structure.
This seems to indicate that M27 has a very complex bedding form.In 1937, the former Soviet astrophysicists Vorontsov Vilyaminov and Kramer put forward a view that the structure of the Fox Dumbbell Nebula was very complex and could not be explained by a single theoretical model.In hisGas Nebula"A series of observations made with large telescopes further confirmed the above conclusion." Like many other planetary nebulae, M27 is also expanding at a rate of about 6 ″. 4 per hundred years.It is inferred that M27 was formed by a supernova explosion about 3000-4000 years ago.
M27 Dumbbell Nebula in Foxy
For those who use small telescopes, this is probably the best planetary nebula.Because it is large and bright, with clear structure.It can be seen with a 3-inch (8cm) telescope, and can be seen very clearly with a 6-inch telescope.But the entire nebula is visible with a telescope 14 inches (36 centimeters) or larger.When observing with a larger telescope, you can see the soft blue green halo surrounding the "dumbbell".The photographic observation with a large telescope shows that the azimuth angle of the long axis of the halo is 125 °, and the nuclear star with the order of 12 is obviously close to the western edge of the dumbbell shape. However, astronomersViboNotice that there are several dark stars that have no physical connection with the nebula.It is difficult to recognize that 12th class nuclear star.In addition, 25 'to the north of the Dumbbell Nebula, there is only one fifth class star, which is 14 stars in the constellation Foxy.
NGC 6830 cluster
NGC 6830It is a small cluster of stars with magnitude+11 or darker.The closer to the center, the tighter.
Foxy
NGC 6940 cluster
NGC 6940thisOpen clusterThe prominent feature of the star cluster is that 6 stars with the magnitude of+9 are distributed in a fine cluster.60 to 100 stars can be seen with a telescope 6 inches (15 centimeters) or larger.
Coat hanger cluster
Collinder 339 cluster
Collinder 339 is also called Brocchi Cluster orCoat hanger cluster。Seen from the earth, it is strikingly similar to the clothes hanger in daily use.Collinder 399 is a brightStar Association, visible with binoculars.If you use a 6 inch (15 cm) or larger telescope, you can see a faint open star cluster next to Fox7 in the east of the Coathanger Cluster, which is NGC 6802.NGC 6802 requires an 8 inch (20 cm) or larger telescope to see a single star.
