Scutum

Scutum


Transit Date of principal star:
30 June


Scutum was invented by the Polish astronomer Johannes Hevelius, and was placed in his posthumous catalogue of 1690, the Prodromus Astronomiae, along with Canes Venatici, Lacerta, Leo Minor, Lynx, Sextans, and Vulpecula.

These newer constellations became better known after being accepted by John Flamsteed in his catalogue published in 1725.

The proper name is Scutum Sobiescianum, Sobieski's Shield, as the constellation pays honour to Jan Sobieski.

Jan Sobieski (1629-1696) was the eldest son of the castellan of Crakow, Jakob Sobieski. He was a brilliant military leader and by 1665 had become the field commander of the Polish army.

The main threat to Poland at this time (indeed to all of central Europe) came from the Turks. While Sobieski attempted to repulse the Turks, the Polish king's envoys ceded all the Ukraine to Turkey. Meanwhile Sobieski won victory after victory. In November of 1673 the king died. Sobieski left the front lines and presented himself as a candidate for the throne back in Warsaw. (The kingship was an elected position.) In May of 1674 he became King John (or Jan) III.

Sobieski returned to his former job as army commander, and after nearly a ten year struggle, he was able to sign the Treaty of Warsaw with Leopold I. Following this treaty, Sobieski further safeguarded Europe from the Turks. Personally leading the Polish cavalry, on 12 September 1683, he broke the Turkish siege on Vienna, and liberated Hungary in the bargain.

Seven years later Hevelius commemorated these events with the inclusion of Scutum Sobiescianum in the heavens.

The asterism, faint as it is, does resemble a simple shield, complete with handle. Some see a dipper as well, standing on its handle. For this you need to include delta and eta Sct.

Scutum is quite dim, with few Bayer stars. There are two Messier objects however and an important variable.


Double stars:

Delta Scuti has a rather faint companion: 4.5, 12; PA 46, separation 15". An optical component is sometimes also given as part of this system (C: 10; PA 130, 52.5").

Epsilon Scuti is a multiple system of very faint companions.

AB: 5, 14.5; 97, 13.6".
C: 13.5; 195, 37.6".
D: 14.5; 312, 15.4".


Variable stars:

Delta Scuti is the prototype of a class of variables. Its range is 4.6-4.79 and it has a period of four hours thirty-nine minutes.

Delta Scuti variables are giant stars with spectra of A to F (occasionally G). They resemble dwarf Cepheids in that they are also pulsatig variables, but they have a smaller amplitude: the delta Scuti amplitude may typically be less than a tenth of a magnitude.

These stars are quite young and are frequently found in open clusters. The brightest delta Scuti variable is not delta Scuti, but rather beta Cassiopeiae.

R Scuti is the brightest RV Tau type variable: 4.2-8.6, period 147 days.

RV Tau stars form another class of pulsating variables, a kind of semi-regular Cepheid. There are not many known, perhaps a hundred or so (the other well known member is R Sagittae). They are supergiants with spectra of F to K (M in some instances) and they are all quite luminous. They are often associated with globular clusters.


Deep Sky Objects:

M11 (NGC 6705), "Wild Duck Cluster", is a splendid open cluster of perhaps four hundred stars which fan out like a flight of startled mallard.

The cluster is one degree SE of R Scuti.

M26 (NGC 6694) is another open cluster in Scutum; about thirty stars that resemble a miniature horseshoe.
The cluster is one degree SE of delta Scuti.

For a more detailed appreciation of Scutum visit the Binocular Section.


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