Scutum (constellation)

Scutum, the shield, is a small constellation in the southern celestial hemisphere. It is one of the 88 constellations accepted by the International Astronomical Union. It was created by Johannes Hevelius in 1690 under the name Scutum Sobiescii or Scutum Sobiescianum (the "Sobieski shield"). »), to honor the Polish king and hero John III Sobieski. It is the only modern constellation associated with a historical figure.

Notable features

With an area of 109 square degrees, Scutum is the fifth smallest constellation. The brightest of its stars, with magnitude 3.85, is α Scuti, an orange giant of spectral type K3III whose surface temperature is 4280 K. Originally part of the constellation of Aquila, in the past α Scuti received the Flamsteed designation 1 Aquilae.

The second brightest star in the constellation is β Scuti, a luminous yellow giant of type G4IIa. It is a spectroscopic binary with an orbital period of 834 days. On the other hand, γ Scuti is a white subgiant with a mass almost three times that of the Sun and a luminosity 150 times greater than the solar luminosity.

But probably the best-known star in the constellation is the variable δ Scuti, prototype of a group of variables that bear its name. These present small fluctuations in their luminosity, far from the wide variations of the Mira variables or the Cepheids, with multiple overlapping pulsation periods. Specifically, the apparent magnitude of δ Scuti varies only 0.19 magnitudes.

Scutum has several other interesting variables. R Scuti is a supergiant of spectral type K0Ibpv—which can fall as low as M3—and an RV Tauri variable; It is enveloped in an atmosphere rich in water vapor as well as a dust cover thousands of times larger than the star itself. RY Scuti is a massive binary system surrounded by a young circumstellar nebula, a rare progenitor of a binary of the type WR + OB. On the other hand, the red supergiant UY Scuti is one of the largest stars in our galaxy.

Beta Scuti is a binary system, with the primary having a spectral type similar to the Sun, although it is 1270 times brighter. Delta Scuti is a bluish-white giant star, which is now approaching in the direction of the Solar System. In 1.3 million years it will come within 10 light years of Earth, and will be much brighter than Sirius by then.

UY Scuti is a red hypergiant pulsating variable star and is also one of the largest stars currently known with a radius more than 1700 times that of the Sun, although some studies give lower estimates. Stephenson 2 DFK 1 is another red hypergiant star and is possibly the largest star currently known, with a radius of 2,150 times that of the Sun. Scutum contains several supergiant star clusters, including RSGC1, Stephenson 2 (which contains Stephenson 2 DFK 1) and RSGC3.

The Milky Way passes through Scutum and one of its brightest regions is located in the extreme northeast of this constellation, in an area called the Scutum Star Cloud. Two objects from the Messier catalog are located in this constellation: M11—also known as the Wild Duck Cluster—, one of the most compact open clusters with an approximate age of 316 million years, and M26, also an open cluster 5160 years distant. light.

This constellation includes Kesteven 73, one of the youngest supernova remains in the Milky Way, with an uncertain age between 750 and 2100 years. It houses the magnetar 1E 1841−045, initially identified as an anomalous X-ray pulsar. Its rotation period, 11.8 s, is one of the longest in this class of objects.

The Pioneer 11 space probe, launched on April 6, 1973, is heading towards this constellation, although it has stopped sending signals since November 1995.

Main stars

Mag. = Apparent magnitude | α = right ascension | δ = declination
Source: The Bright Star Catalogue, 5th ed. revised., Hippparcos Catalog, ESA SP-1200

Deep sky objects

Scutum has several open and globular clusters, as well as some planetary nebulae. Among the most notable galactic clusters are M11 (NGC 6705), the Wild Duck Cluster, and M26 (NGC 6694). The globular cluster NGC 6712 and the planetary nebula IC 1295 are located in the eastern part of this constellation, just 24 arc minutes apart.

Kesteven 73 and SNR G021.5-00.9 are young supernova remnants framed in this constellation. W41 and Kesteven 69 are also supernova remnants, but considerably older.

History

Scutum is a modern constellation, being discovered at the end of the 17th century. Therefore, it does not have any mythological element associated with it.

Scutum was baptized in 1684 by the Polish astronomer Johannes Hevelius (Jan Heweliusz), who originally called it Scutum Sobiescianum (Sobieski Shield) to commemorate the victory of the Christian forces led by the king Polish John III Sobieski (Jan III Sobieski) at the Battle of Vienna in 1683. The name was later shortened to Scutum.

Scutum's five bright stars (α Sct, β Sct, δ Sct, ε Sct and η Sct) were previously known as 1, 6, 2, 3 and 9 Aquilae respectively.

The Scutum constellation was adopted by the International Astronomical Union in 1922 as one of the 88 constellations that cover the entire sky, with the official abbreviation of "Sct". The boundaries of the constellations are defined by a quadrilateral. In the equatorial coordinate system, the right ascension coordinates of these limits are between 18h 21.6m and 18h 59.3m, while the declination coordinates are between -3.83° and -15.94 °.

Coincidentally, the Chinese also associated these stars with combat armor, incorporating them into the major asterism known as Tien Pien, that is, the Celestial Helmet (or Helmet).