Scutum constellation lies in the southern sky. Its name means ‘shield’ in Latin. It is the fifth smallest constellation in the sky. Scutum is the 84th constellation in size, occupying an area of only 109 square degrees. It is located in the fourth quadrant of the southern hemisphere (SQ4) and can be seen at latitudes between +80° and -90°. The neighboring constellations are Aquila, Sagittarius and Serpens Cauda.
[http://www.constellation-guide.com/constellation-list/scutum-constellation/]
Scutum shown under the name Scutum Sobiesii on Chart IX of the Uranographia of Johann Bode (1801).
Scutum was introduced in 1684 by the Polish astronomer Johannes Hevelius under the title Scutum Sobiescianum, Sobieski’s Shield. He named it in honour of King John III Sobieski of Poland who helped Hevelius rebuild his observatory after a disastrous fire in 1679.
Hevelius’s description and chart of the constellation first appeared in August 1684 in Acta Eruditorum, a leading scientific journal of the day. Hevelius quoted Edmond Halley’s invention six years earlier of Robur Carolinum, honouring King Charles II of England, as the precedent. Robur Carolinum did not survive but Scutum did, and is in fact the only constellation introduced for political reasons that is still in use.
Even so, Scutum nearly didn’t make it. John Flamsteed ignored it in his catalogue and atlas, although he accepted six other Hevelius inventions. Johann Bode reinstated it to the sky in his Uranometria of 1801 under the name Scutum Sobiesii. The American astronomer Benjamin Gould included it as plain Scutum in his Uranometria Argentina catalogue of 1879 and allocated Greek letters to its stars for the first time, cementing its permanence.
In the Chinese constellation system, five or six stars of northern Scutum, including Alpha, Beta, and Eta Scuti, were grouped with others in Aquila to form a nine-star constellation called Tianbian. This represented a team of trade officials overseeing the organization and operation of markets. The area of sky to the west, incorporating much of Ophiuchus and Serpens plus southern Hercules, was visualized as a marketplace.
[http://www.ianridpath.com/startales/scutum.htm]
[http://www.steamboattoday.com/news/2010/aug/24/jimmy-westlake-scutum-star-cloud/]
[http://astropixels.com/constellations/charts/Sct.html]
Alpha Scuti (Ionnina) is the brightest star in the constellation. It is an orange giant with the stellar classification of K2III. It has an apparent magnitude of 3.85 and is approximately 174 light years distant from Earth. The star used to belong to Aquila constellation and was previously designated 1 Aquilae. It is a known variable star, with its brightness varying by about 10 percent. Alpha Scuti is 132 times more luminous than the Sun and has a mass 1.7 times solar. It is believed to be at least 2 billion years old.
Beta Scuti is the second brightest star in Scutum constellation. It has an apparent magnitude of 4.22 and is approximately 690 light years distant from the solar system. It is a yellow bright giant star with the stellar classification G5II, about 1,270 times more luminous than the Sun. The star used to be known as 6 Aquilae.
Zeta Scuti is a yellow giant with the stellar classification of G9 IIIb Fe-0.5. It has an apparent magnitude of 4.68 and is approximately 207 light years distant from the Sun. It is the third brightest star in the constellation. Zeta Scuti is an astrometric binary system, a binary star that seemingly orbits around an empty space, without a visible or detectable companion. The star has an orbital period of 6.5 years.
Gamma Scuti is a white subgiant star belonging to the stellar class A1IV/V. It has an apparent magnitude of 4.67 and is located about 291 light years from Earth. It is the fourth brightest star in the constellation.
Delta Scuti is a yellow-white giant star. It has a stellar classification of F2 IIIp, and a mass 2.23 times that of the Sun. It has an apparent magnitude of 4.72, and it is approximately 202 light years distant from the solar system. It has two line-of-sight companions, one with a visual magnitude of 12.2 located 15.2 arc seconds away, and another with a magnitude of 9.2, 53 arc seconds away.
This star is a well-known variable star, one that serves as a prototype for an entire class of variables, the Delta Scuti variables, sometimes also known as dwarf Cepheids. These are variable stars that exhibit fluctuations in luminosity as a result of both radial and non-radial pulsations of their surfaces. Delta Scuti has a 0.19377 day period of variability and its brightness varies by 0.2 magnitudes.
[http://www.constellation-guide.com/constellation-list/scutum-constellation/]
Dense starfield around the red supergiant star UY Scuti (brightest star in the image) as seen from the Rutherfurd Observatory in the Columbia University in New York, United States. The picture was captured in 2011.
UY Scuti is a red supergiant and pulsating variable star in the constellation Scutum. It is a current and leading candidate for being the largest known star by radius and is also one of the most luminous of its kind. It has an estimated radius of 1,708 solar radii, thus a volume nearly 5 billion times that of the Sun. It is approximately 2.9 kiloparsecs (9,500 light-years) from Earth. If placed at the center of the Solar System, its photosphere would at least engulf the orbit of Jupiter.
The star is classified as a semiregular variable with an approximate pulsation period of 740 days. It has the total luminosity of 340,000 L☉. UY Scuti’s mass is uncertain, primarily because it has no visible companion star by which its mass can be measured through gravitational interference. Stellar evolutionary models conclude that the initial mass of a star (the mass of a star when it is formed) reaching the red supergiant stage like UY Scuti would have been around 25 M☉ (possibly up to 40 M☉ for a non-rotating star), and has probably lost more than half of that.
Based on current models of stellar evolution, UY Scuti has begun to fuse helium and continues to fuse hydrogen in a shell around the core. The location of UY Scuti deep within the Milky Way disc suggests that it is a metal-rich star. After fusing heavy elements, its core will begin to produce iron, disrupting the balance of gravity and radiation in its core and resulting in a core collapse supernova. It is expected that stars like UY Scuti should evolve back to hotter temperatures to become a yellow hypergiant, luminous blue variable, or a Wolf–Rayet star, creating a strong stellar wind that will eject its outer layers and expose the core, before exploding as a type IIb, IIn, or type Ib/Ic supernova.
[https://en.wikipedia.org/wiki/UY_Scuti]
M11 (NGC 6705 or the Wild Duck Cluster) is an open cluster in Scutum:
The Wild Duck Cluster (M11- NGC 6705)
The Wild Duck Cluster (also known as Messier 11, or NGC 6705) is an open cluster in the constellation Scutum. It was discovered by Gottfried Kirch in 1681. Charles Messier included it in his catalogue in 1764.
The Wild Duck Cluster is one of the richest and most compact of the known open clusters, containing about 2900 stars. Its age has been estimated to about 250 million years. Its name derives from the brighter stars forming a triangle which could resemble a flying flock of ducks (or, from other angles, one swimming duck).
[https://en.wikipedia.org/wiki/Wild_Duck_Cluster]
M11 is part of the Scutum Star Cloud:
The Scutum Star Cloud contains an immense number of stars and is bounded and crossed by numerous dark nebulae. Looking in its direction, we see the next spiral arm of the Milky Way inward from our own at a distance of 6,000 light years. M11 (Wild Duck Cluster) is the bright blob left of center.
If the ducks in the Wild Duck Cluster (M11) in the constellation Scutum should ever decide to seek refuge, they’ll have their choice of many a dark and shapely pond. The entire region is saturated with them- inky, starless areas of all shapes and depths that dot the Shield like Minnesota’s 10,000 lakes.
Of course we’re talking about dark nebulae, enormous clouds of interstellar dust and gas that blot out the more distant stars, creating the illusion of holes or in the starry fabric of the Milky Way. They’re made of materials similar to those of bright nebulae like Orion or the Lagoon, but lack a nearby star or stars to set them aglow.
Although the density of these dark clouds is only on the order of 100-300 molecules per cubic centimeter, it really adds up over a depth of several light years or more. Some dark nebulae appear nearly opaque without a single star to relieve the gloom.
Deep inside these clouds, where hydrogen, carbon dust, water ice, and other compounds feel the contractive force of gravity strongest, new stars are forming that only radio and infrared telescopes can see. Dark nebulae are crucial to the life cycle of the universe because they provide the raw materials for the next generation of stars and planets. It may appear you’re staring into nothingness, but nothing could be further from the truth.
[http://www.skyandtelescope.com/observing/dive-into-scutums-dark-nebulae071520151507/]
IC 1295 is a planetary nebula in Scutum:
A ghostly green bubble
This intriguing new picture from ESO’s Very Large Telescope shows the glowing green planetary nebula IC 1295 surrounding a dim and dying star located about 3,300 light-years away in the constellation of Scutum (The Shield). This is the most detailed picture of this object ever taken.
Stars the size of the Sun end their lives as tiny and faint white dwarf stars. But as they make the final transition into retirement their atmospheres are blown away into space. For a few tens of thousands of years they are surrounded by the spectacular and colorful glowing clouds of ionized gas known as planetary nebulae.
The planetary nebula IC 1295 has the unusual feature of being surrounded by multiple shells that make it resemble a micro-organism seen under a microscope, with many layers corresponding to the membranes of a cell.
These bubbles are made out of gas that used to be the star’s atmosphere. This gas has been expelled by unstable fusion reactions in the star’s core that generated sudden releases of energy, like huge thermonuclear belches. The gas is bathed in strong ultraviolet radiation from the aging star, which makes the gas glow. Different chemical elements glow with different colors and the ghostly green shade that is prominent in IC 1295 comes from ionized oxygen.
At the center of the image, you can see the burnt-out remnant of the star’s core as a bright blue-white spot at the heart of the nebula. The central star will become a very faint white dwarf and slowly cool down over many billions of years.
Stars with masses like the Sun and up to eight times that of the Sun, will form planetary nebulae as they enter the final phase of their existence. The Sun is 4.6 billion years old and it will likely live another four billion years.
Despite the name, planetary nebulae have nothing to do with planets. This descriptive term was applied to some early discoveries because of the visual similarity of these unusual objects to the outer planets Uranus and Neptune, when viewed through early telescopes, and it has been catchy enough to survive. These objects were shown to be glowing gas by early spectroscopic observations in the nineteenth century.
This image was captured by ESO’s Very Large Telescope, located on Cerro Paranal in the Atacama Desert of northern Chile, using the FORS instrument (FOcal Reducer Spectrograph). Exposures taken through three different filters that passed blue light (colored blue), visible light (colored green), and red light (colored red) have been combined to make this picture.
[https://www.eso.org/public/news/eso1317/]
G21.5-0.9 is the remnant of a supernova in Scutum:
G21.5-0.9: Cosmic shell-seekers find a beauty
This image, made by combining 150 hours of archived Chandra data, shows the remnant of a supernova explosion. The central bright cloud of high-energy electrons is surrounded by a distinctive shell of hot gas.
The shell is due to a shock wave generated as the material ejected by the supernova plows into interstellar matter. The shock wave heats gas to millions of degrees, producing X-rays in the process.
Although many supernovas leave behind bright shells, others do not. This supernova remnant, identified as G21.5-0.9 by radio astronomers 30 years ago, was considered to be one that had no shell until it was revealed by Chandra.
The absence of a detectable shell around this and similar supernova remnants had led astronomers to speculate that another, weaker type of explosion had occurred. Now this hypothesis seems unlikely, and it is probable that the explosion of every massive star sends a strong shock wave rumbling through interstellar space.
Some supernova shells are faint because of the lack of material around the star before it explodes. Rapid mass loss from the star before the explosion could have cleared out the region.
By examining the properties of the shell with an X-ray telescope, astronomers can work back to deduce the age (a few thousand years), and energy of the explosion, as well as information about the state of the star a million years before it exploded. The star that produced this supernova shell is thought to have been at least 10 times as massive as the Sun.
[http://chandra.harvard.edu/photo/2005/g21/index.html]
[https://en.wikipedia.org/wiki/Scutum]
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