Sculptor
Written by Tammy Plotner
Sculptor
The small constellation of Sculptor is located south of the ecliptic plane. It was originally charted by Abbe Nicolas Louis de Lacaille who named it "Apparatus Sculptoris" – the Sculptor's Studio. It was later adopted by the International Astronomical Union as one of the 88 modern constellations and its name shortened to Sculptor. It covers 475 square degrees of sky and ranks 36th in constellation size. Sculptor has 4 main stars in its asterism and contains 18 Bayer Flamsteed designated stars within its boundaries. It is bordered by the constellations of Cetus, Aquarius, Piscis Austrinus, Grus, Phoenix and Fornax. Sculptor is visible to all observers located at latitudes between +50° and ?90° and is best seen at culmination during the month of November.
Since Sculptor is considered a "new" constellation, there is no mythology associated with it – only the story of how its name came to be. French astronomer Nicolas Louis de Lacaille charted the southern hemisphere skies from the Cape of Good Hope during the time period of 1751-1752 and his love of all objects in art and science were portrayed in the names he assigned to his newly created constellations. Depicted on his chart as a fanciful tripod with a carved bust and the artist's tools, " l'Atelier du Sculpteur" was later shortened to the simpler term – Sculptor – and adopted by the International Astronomical Union as a permanent constellation.
Let's begin our binocular tour of Sculptor with its brightest star – Alpha – the "a" symbol on our map. Located approximately 680 light years from Earth, Alpha Sculptoris is a blue-white B-type giant classified as an SX Arietis type variable star and its magnitude varies by 0.01. While changes in brightness and spectral composition that small would never be detectable to the human eye, at one time it was believed to be caused by orbiting black hole – but were later identified to chemical variations in its atmosphere. While Alpha doesn't appear to be much, take a closer look… It still shines over 1700 times brighter than our own Sun – yet is only 7 times larger! It is one of the weirdest stars you will ever see – a helium weak star that rotates ever-so-slowly. Thanks to this creeping motion, Alpha can generate a huge stellar magnetic field which allows it to concentrate its chemicals in certain areas – and even flip its magnetic poles!
For other binocular attractions, take a look at Beta Sculptoris – the "B" symbol. It's a a blue-white B-type subgiant star positioned approximately 178 light years from our solar system. Or Gamma – the "Y" symbol – it's an an orange K-type giant that is 179 light years away… or even Delta – the "8" symbol. Delta is is a triple star system that's 139 light years distant and the primary component, Delta Sculptoris A, is a white A-type main sequence dwarf star! Take out the telescope and look for a faint, 11th magnitude companion, Delta Sculptoris B, 4 arcseconds, or more than 175 AU, away from it. Orbiting this pair at the much greater separation of 74 arcseconds, is the third player in this drama, the yellow G-type Delta Sculptoris C, which has an apparent stellar magnitude of 9.4.
For telescope observers, one of the greatest challenges you will ever encounter is the Sculptor Dwarf Galaxy (RA 01 : 00.0 Dec -33 : 42). Discovered by Harlow Shapley on photographic plates in 1937, this extreme low surface brightness elliptical galaxy is a member of our own local galaxy group and is about 290,000 light-years away. Use at least a 150mm telescope and an absolute minimum of magnification to spot just a compression in the starfield at this location!
Now, let's take a look at the Sculptor Group – a a loose group of galaxies near the south galactic pole and one of the closest groups of galaxies to the Milky Way Local Group. At the head of this class is the Sculptor Galaxy – NGC 253 – is an intermediate spiral galaxy (RA 0 : 47.6 Dec -25 : 17). Discovered by Caroline Herschel, this brilliant magnitude 7 beauty is a starburst galaxy, undergoing periods of intense star formation, and can easily be seen with a small telescope or binoculars. However, companion galaxies NGC 247, PGC 2881, PGC 2933, Sculptor-dE1, and UGCA 15 will need much more aperture! This association forms a gravitationally bound core near the center of the group and most other galaxies associated with the Sculptor Group are only weakly gravitationally bound to this core.
While there, drop south and take a look at NGC 288 (RA 00:52:47.5 Dec -26:35:24). This 8th magnitude globular cluster was discovered by Sir William Herschel and can often be spotted in the same binocular field as NGC 253. While this small globular doesn't appear to be worthy of much attention, think again… In the late 1980's it was discovered that it is about 3 billion years older than other globular clusters!
Need to take a look at the home of a supernova? The stop by NGC 150 (RA 0 : 34.3 Dec -27 : 48). Home to an event in 1990, this spiral galaxy is also a great radio emitter, too. Even though it will require a larger telescope to catch anything at magnitude 11, it will still give a nice oblong presentation with a bright core region.
For another binocular and small telescope galaxy, take a look at NGC 55 (RA 0 : 14.9 Dec -39 : 11). This huge, magnitude 8 irregular galaxy gives a great, near edge-on presentation and is believed to be very similar to the Large Magellanic Cloud (LMC). Spanning about 50,000 light-years, large telescopes will be able to resolve out brighter regions of emission nebulae – large star forming regions producing new stars.
For an unusual mid-size telescope challenge, take a look at NGC 7793 (RA 23 : 57.8 Dec -32 : 35). At magnitude 9 and about 9 arc minutes in size, you'll find 10 million light year distant Bennett 130 to be a beautiful spiral with a sharp nucleus and round, hazy spiral galaxy structure. It was discovered by James Dunlop and it is also part of the Sculptor Group. In 2005, the Spitzer Space Telescope was able to pierce through its clouds and take a closer look at star formation driving the evolution of the galaxy.
Don't forget while you're in Sculptor to take on large telescope challenges like NGC 7713 (RA 23 : 36.5 Dec -37 : 56) – a 12th magnitude spiral galaxy, NGC 7755 (RA 23 : 47.9 Dec -30 : 31), also 12th magnitude, but a much smaller elliptical galaxy. How about small and faint NGC 24 (RA 0 : 09.9 Dec -24 : 58) or far easier NGC 134 (RA 0 : 30.4 Dec -33 : 15). There's galaxies galore just waiting to be carved out of Sculptor and enjoyed!
Chart Courtesy of Your Sky.
Filed under: Astronomy
