The shield is a very small constellation of the southern hemisphere located near the celestial equator and visible in latitudes from +80 to -94 degrees. It is well viewed from the territory of Russia. The area occupied by the Shield is only 109.1 square degrees (0.26% of the night sky), which corresponds to the 84th position in size among 88 officially known constellations.
The shield cannot boast of bright stars, asterisms or luminaries of navigational significance, however, it still contains several interesting astronomical objects. It is especially noteworthy that the constellation is located within one of the densest zones of the Milky Way.
General description and photo of the constellation Shield in the sky
The international Latin name for this constellation is Scutum (translated as "shield"). He is currently part of the Hercules group. Skutum is one of two constellations named after real people (the second is Coma Berenice).
The shield has only 20 weakly visible bodies that can be seen with the naked eye only in a perfectly clear night sky. But within the constellation you can see the famous open clusters (the so-called star clouds). They can be examined more carefully with binoculars or a telescope.
Approximately 270 stars of the constellation Shield were detailed and described using satellite systems. Among them, ten are distinguished. Since the difference between the degree of removal of different Skutum stars from the Earth is too large, it is impossible to arithmetically calculate the distance to the Shield.
In the photo, the constellation Shield looks like a small random cluster of luminous points that do not form a geometric shape. Full visibility is possible in latitudes south of 74 degrees. The best time to observe the constellation is July.
Location in the sky
The location of the constellation Shield in the sky belongs to the fourth quadrant of the southern hemisphere (SQ4) and enters the rich zone of the Milky Way. The value of the right ascension (the coordinate determining the position of the celestial body) is 19 hours. The sketchy image of Skutum in the sky resembles a shield, the peaks of which are the brightest stars.
The shield is adjacent to three constellations:
- Eagle;
- Sagittarius;
- The snake.
Significantly higher than Skutum is the star Vega.
To visually determine where the Shield constellation is, you need to look along the Milky Way to the south in the direction of the Eagle constellation, whose alpha and lambda are located on a straight line pointing to the desired object.
History
The shield is not among the constellations described in the ancient astronomical map of Ptolemy. This object was designated only in 1864 by Pole Jan Hevelius and after 6 years was added to the heavenly atlas “Uranography”. Since then, the Shield is included in a group of 88 officially designated constellations.
The origin of the name is connected with a historical event - the victory of the Poles over the Turks in the Battle of Vienna, which took place in 1683. The astronomer named the constellation "Sobieski Shield" in honor of the commander who led the battle, who was also the king of Poland.
Shield Stars
The shield includes a relatively small number of stars, of which only 20 can be distinguished with the naked eye. The brightest luminaries have the fourth and fifth magnitudes. The main stars include alpha, beta, zeta, gamma, delta, this, epsilon, R, S and PSB.
The brightest star of Skutum with an apparent visibility of 3.85 is alpha, otherwise called Ioannina. It is distant from the Sun at a distance of 53.43 light years. The second place in brightness belongs to Beta Shield. The faintest star visible to the naked eye is HD 174208 with a brightness of 5.99, which almost corresponds to the line of sight.
The farthest object of Skutum is the star HIP 90204, located at a distance of 326,163.3 light years from the Sun.
Brief description of the main stars of the Shield| Alpha | The absolute magnitude is -0.08, refers to the spectral class K (orange giant) |
| Beta | It is a multiple system, among which there are 2 main objects - A and B beta. The first star is a yellow giant of class G, and the second is a white-blue star. Beta’s total magnitude is 4.23m. This system used to be called 6 Aquilae |
| Zeta | A yellow giant removed by 207 light years from the Sun, classified as G9 IIIb Fe-0.5. The apparent apparent magnitude of this star is 4.68 |
| Gamma | A white star of class A1IV / V with a magnitude of 4.67, 291 light-years distant from Earth. Is the fourth brightest luminary of Skutum |
| Delta | The famous giant variable pulsating star (is the first object of this type discovered in the sky). Stars of this class are otherwise called dwarf Cepheids, the peculiarity of which is that surface pulsations occur both in the longitudinal and in the transverse directions. The delta belongs to the spectral class F2 IIIp (yellow-white giant) and has an apparent apparent magnitude of 4.72 with a periodic change in brightness by 0.2. The star has two satellites and is 202 light years from the solar system. |
| This | An orange giant whose diameter is 10 times larger than that of the Sun, and its mass is 1.4 times. It belongs to the spectral class K1III and has an apparent magnitude of 4.83. |
| Epsilon | 4.88 multi-star system with 523 light-years distant from Earth. By spectral classification, it belongs to the G8II group, corresponding to the bright yellow giants. |
| R | The yellow supergiant, classified as RV Tauri, is the brightest variable in this group with an apparent apparent magnitude of 4.2–8.6. Luminosity variations occur as a result of radial surface pulsations. The star is 1,400 light-years distant from the sun. |
| S | The red giant, a type of carbon star, has a visible luster of 6.81. A star 1289 light-years distant from Earth |
| PSB B1829-10 | A magnetized neutron rotating star with a magnitude of 5.28, 30 thousand light-years distant from the solar system. It is a pulsar emitting a beam of electromagnetic radiation. The mass of this star is 1.4 more than that of the Sun. |
Skutum also includes the largest known star to date - UY Shield. Its radius is 1708 times greater than that of the Sun.
Noteworthy Astronomical Objects
Interesting objects of the deep sky in the constellation Shield primarily include star clusters of various nature. In a clear night sky, some of them can be seen even without binoculars. These are the so-called famous clusters Messier 11 and 26, which are otherwise called large stellar clouds.
In addition to them, the composition of Skutum includes:
- 2 globular clusters;
- 145 nebulae (52 planetary, 91 dark and 3 diffuse);
- 19 open clusters.
Wild Duck Cluster
Wild Duck is the open cluster Messier 11, which is one of the most dense open star clusters and contains 2900 stars. The apparent magnitude of this deep sky object is 6.3. The cluster is located at a distance of 6200 light years from the solar system. When viewed through binoculars, the object looks like a small foggy cloud with a well-defined core.
The cluster was named due to the fact that its brightest stars form a figure resembling a flock of flying ducks. The object was discovered in the XVII century by Gottfried Kirch and after 83 years was listed in Messier.
Messier 26
Compared to Wild Duck, it contains a significantly smaller number of stars (90) that fit on an area with a diameter of 22 light years. The cluster was discovered by Charles Monsieur in 1764. The distance of the object from the Sun is 5 thousand light years.
The cluster looks like a small dense grouping with a discharged zone in the center. The low density in the core of the cluster can be due to the accumulation of dark interstellar matter on the observation path between the cluster and the Earth. The total stellar magnitude of the cluster is 8, and the brightness of the brightest star within it is 11.9.
Globular Cluster NGC 6712
It differs in rather large sizes and contains about a million stars, the total brightness of which is 8.1 m . The object was first discovered in 1749, but as a globular cluster was classified only in the 30s of the XIX century.
The physical diameter of this cluster is 64 light years.