[http://www.slivoski.com/astronomy/sculptor.htm]
Sculptor is a small and faint constellation in the southern sky. It represents a sculptor. It was introduced by Nicolas Louis de Lacaille in the 18th century. Sculptor is bordered by Aquarius and Cetus to the north, Fornax to the east, Phoenix to the south, Grus to the southwest, and Piscis Austrinus to the west. The bright star Fomalhaut is nearby. In the equatorial coordinate system, the right ascension coordinates of the constellation lie between 23h 06.4m and 01h 45.5m, while the declination coordinates are between −24.80° and −39.37°. The whole constellation is visible to observers south of latitude 50°N.
Sculptor, shown under the name Apparatus Sculptoris, on Chart XVII of the Uranographia of Johann Bode (1801).
The faint constellation south of Cetus and Aquarius was invented by the French astronomer Nicolas Louis de Lacaille during his mapping of the southern skies in 1751-52. His original name for it, given on his planisphere of 1756, was l’Atelier du Sculpteur, the sculptor’s studio. It consisted of a carved head on a tripod table, with the artist’s mallet and two chisels on a block of marble next to it. On Lacaille’s 1763 planisphere the title was Latinized to Apparatus Sculptoris.
Johann Bode in 1801 dispensed with the block of marble and moved the sculptor’s tools to the top of the table along with the carved bust, as depicted here. In place of the marble block he created the constellation Machina Electrica, but that figure never achieved wide currency.
In 1844 the English astronomer John Herschel proposed shortening the name to Sculptor. This suggestion was adopted by Francis Baily in his British Association Catalogue of 1845, and it has been known simply as Sculptor ever since.
[http://www.ianridpath.com/startales/sculptor.htm]
[http://oneminuteastronomer.com/4786/silver-coin-galaxy/]
Constellations of Sculptor and Fornax
[https://www.davidmalin.com/fujii/source/Scl.html]
No stars brighter than 3rd magnitude are located in Sculptor. This is explained by the fact that Sculptor contains the south galactic pole where stellar density is very low.
Alpha Sculptoris (α Scl) is a blue-white B-type giant star, 780 light-years (240 parsecs) away. It has an apparent visual magnitude of +4.30. The luminosity of α Scl is around 1,500 times that of the Sun while its surface temperature is 13,600 K. Its radius is calculated to be seven times solar while its mass is five times that of the Sun.
[https://en.wikipedia.org/wiki/Alpha_Sculptoris]
Beta Sculptoris (β Scl) is another blue-white hued B-type giant star. It has an apparent visual magnitude of 4.37, which is bright enough to be seen with the naked eye. It is located 174 light years from the Sun. The star has nearly three times the mass of the Sun and double the Sun’s radius. It is radiating 81 times the Sun’s luminosity from its photosphere at an effective temperature of 12,110 K.
[https://en.wikipedia.org/wiki/Beta_Sculptoris]
Gamma Sculptoris (γ Scl) is an orange-hued K-type giant star with a stellar classification of K1 III. It is located about 182 light years from the Sun. It is bright enough to be visible to the naked eye with an apparent visual magnitude of 4.41. The star has 1.60 times the mass of the Sun and it has expanded to 12 times the Sun’s radius. It is radiating 72 times the Sun’s luminosity from its enlarged photosphere at an effective temperature of 4,578 K.
[https://en.wikipedia.org/wiki/Gamma_Sculptoris]
Delta Sculptoris (δ Scl) is a triple star system, approximately 137.4 light years from Earth. The primary component, Delta Sculptoris A, is a white A-type main sequence dwarf, with an apparent magnitude of +4.59. It has a faint 11.6 magnitude companion, Delta Sculptoris B, 4 arcseconds, or more than 175 astronomical units, away from it. Orbiting this pair at the much greater separation of 74 arcseconds, is the yellow G-type Delta Sculptoris C, which has an apparent magnitude of +9.4.
[https://en.wikipedia.org/wiki/Delta_Sculptoris]
R Sculptoris is an asymptotic giant branch semi-regular variable red giant star located 1,500 light-years (460 parsecs) away in the constellation of Sculptor. Observations have revealed a spiral structure in the material around it. The spiral is suspected to be caused by an unseen companion star:
A spiral nebula surrounding star R Sculptoris
What’s happening around that star? An unusual spiral structure has been discovered around the Milky Way star R Sculptoris, a red giant star located about 1,500 light years away toward the constellation of the Sculptor (Sculptoris). The star was observed with the new Atacama Large Millimeter/submillimeter Array (ALMA), the most powerful telescopic array observing near millimeter wavelengths, that part of the spectrum situated well beyond red light but before microwaves and radio waves. Data from ALMA observations was used to create a 3D visualization of the gas and dust immediately surrounding the star. A digital slice through this data showed the unexpected spiral structure. Although unusual, a similar spiral pattern was discovered in visible light recently around LL Pegasi. Upon analyzing the data, a hypothesis was drawn that the red giant star in R Sculptoris might be puffing gas toward an unseen binary companion star. The dynamics of this system might be particularly insightful because it may be giving clues as to how giant stars evolve toward the end of their lives- and so release some constituent elements back to the interstellar medium so that new stars may form.
[http://apod.nasa.gov/apod/ap121016.html]
Gliese 1 is a red dwarf in the constellation Sculptor, which is found in the southern celestial hemisphere. It is one of the closest stars to the Sun, at an approximate distance of 14.2 light years. Because of its proximity to the Earth it is a frequent object of study and much is known about its physical properties and composition. However, with an apparent magnitude of about 8.5 it is too faint to be seen with the naked eye.
[https://en.wikipedia.org/wiki/Gliese_1]
HD 4113 is an 8th magnitude metal rich G5V star located approximately 144 light-years away in the constellation Sculptor. On 26 October 2007, a planet was found with a minimum mass one and half times that of Jupiter orbiting at 1.28 AU away from HD 4113.
[https://en.wikipedia.org/wiki/HD_4113]
HD 4208 is another 8th magnitude Sun-like star, located approximately 106 light years away. Its spectral type is G5V, similar to our Sun, only slightly cooler and dimmer. It is not visible to the unaided eye, but with binoculars or small telescope it should be an easy target. In 2001, a planet was discovered orbiting the star.
[https://en.wikipedia.org/wiki/HD_4208]
Artist’s impression of a star like WASP-8
WASP-8 is a magnitude 9.9 main-sequence yellow dwarf star. It is reported to be a G-type star of temperature 5,600 K, mass of 0.93 solar masses, radius of 0.93 solar radius, and a luminosity of 0.79 of solar luminosity. There is a companion star located 4 arcseconds away with the same proper motion indicating a stellar binary system.
The star is orbited by two known extrasolar planet, designated WASP-8b and WASP-8c. They was catalogued as part of the SuperWASP mission and discovered by the astronomical transit method. WASP-8c has the longest orbital period of any exoplanet discovered by WASP with a period of 4,323 days, over 400 times the period of the second-furthest planet, WASP-117b with a period of 10.02 days.
Measurements of WASP-8b’s radius and mass give it an estimated density of 2.53 g/cm3, about twice the density of Jupiter.
[https://en.wikipedia.org/wiki/WASP-8]
NGC 134 is a barred spiral galaxy that resembles the Milky Way with its spiral arms loosely wrapped around a bright, bar-shaped central region. Its loosely bound spiral arms categorize it as Hubble-type Sbc. It is 60 million light years away, and part of the Sculptor constellation:
[https://en.wikipedia.org/wiki/NGC_134]
Sculptor Galaxy NGC 134
NGC 134 is probably not the best known spiral galaxy in the constellation Sculptor. Still, the tantalizing island universe is a clearly a telescopic treasure in southern skies. It shares a bright core, clumpy dust lanes, and loosely wrapped spiral arms with spiky foreground stars of the Milky Way and the more diminutive galaxy NGC 131 in this sharp cosmic vista. From a distance of about 60 million light-years, NGC 134 is seen tilted nearly edge-on. It spans some 150,000 light-years, making it even larger than our own Milky Way galaxy. NGC 134's warped disk and faint extensions give the appearance of past gravitational interactions with neighboring galaxies. Like the much closer and brighter Sculptor galaxy NGC 253, tendrils of dust appear to rise from a galactic disk sprinkled with blue star clusters and pinkish star forming regions.
[https://apod.nasa.gov/apod/ap160304.html]
The Sculptor Group is a loose group of galaxies near the south galactic pole. The group is one of the closest groups of galaxies to the Local Group; the distance to the center of the group from the Milky Way is approximately 3.9 Mpc (12.7 Mly).
[https://en.wikipedia.org/wiki/Sculptor_Group]
The Sculptor Galaxy (NGC 253), a barred spiral galaxy and the largest member of the Sculptor Group, lies near the border between Sculptor and Cetus:
NGC 253: Dusty Island Universe
Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest. Some call it the Silver Dollar Galaxy for its appearance in small telescopes, or just the Sculptor Galaxy for its location within the boundaries of the southern constellation Sculptor. First swept up in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies. In addition to its spiral dust lanes, tendrils of dust seem to be rising from a galactic disk laced with young star clusters and star forming regions in this sharp color image. The high dust content accompanies frantic star formation, earning NGC 253 the designation of a starburst galaxy. NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to massive black holes near the galaxy’s center.
[http://apod.nasa.gov/apod/ap140726.html]
Another prominent member of the Sculptor Group is the irregular galaxy NGC 55:
Irregular Galaxy NGC 55
Irregular galaxy NGC 55 is thought to be similar to the Large Magellanic Cloud (LMC). But while the LMC is about 180,000 light-years away and is a well- known satellite of our own Milky Way Galaxy, NGC 55 is more like 6 million light-years distant and is a member of the Sculptor Galaxy Group. Classified as an irregular galaxy, in deep exposures the LMC itself resembles a barred disk galaxy. However, spanning about 50,000 light-years, NGC 55 is seen nearly edge-on, presenting a flattened, narrow profile in contrast with our face-on view of the LMC. Just as large star forming regions create emission nebulae in the LMC, NGC 55 is also seen to be producing new stars. This gorgeous galaxy portrait highlights a bright core, telltale pinkish emission regions, and young blue star clusters in NGC 55.
[http://apod.nasa.gov/apod/ap081010.html]
One unique galaxy in Sculptor is the Cartwheel Galaxy, at a distance of 500 million light-years. The result of a merger around 300 million years ago, the Cartwheel Galaxy has a core of older, yellow stars, and an outer ring of younger, blue stars, which has a diameter of 100,000 light-years. The smaller galaxy in the collision is now incorporated into the core, after moving from a distance of 250,000 light-years. The shock waves from the collision sparked extensive star formation in the outer ring:
A spectacular head-on collision between two galaxies is seen in this NASA Hubble Space Telescope true-color image of the Cartwheel Galaxy.
The Cartwheel Galaxy (also known as ESO 350-40) is a lenticular galaxy and ring galaxy about 500 million light-years away in the constellation Sculptor. It is an estimated 150,000 light-years across, has a mass of about 2.9-4.8 × 10^9 solar masses, and rotates at 217 km/s. It was discovered by Fritz Zwicky in 1941.
The galaxy was once a normal spiral galaxy before it apparently underwent a head-on collision with a smaller companion approximately 200 million years ago (i.e., 200 million years prior to the image). When the nearby galaxy passed through the Cartwheel Galaxy, the force of the collision caused a powerful shock wave through the galaxy, like a rock being tossed into a sand-bed. Moving at high speed, the shock wave swept up gas and dust, creating a starburst around the galaxy's center portion that were unscathed. This explains the bluish ring around the center, brighter portion. It can be seen that the galaxy is beginning to retake the form of a normal spiral galaxy, with arms spreading out from a central core.
[https://en.wikipedia.org/wiki/Cartwheel_Galaxy]
The constellation also contains the Sculptor Dwarf, a dwarf galaxy which is a member of the Local Group:
A shy galactic neighbor
The Sculptor Dwarf Galaxy, pictured in this new image from the Wide Field Imager camera, installed on the 2.2-metre MPG/ESO telescope at ESO’s La Silla Observatory, is a close neighbor of our galaxy, the Milky Way. Despite their close proximity, both galaxies have very distinct histories and characters. This galaxy is much smaller and older than the Milky Way, making it a valuable subject for studying both star and galaxy formation in the early Universe. However, due to its faintness, studying this object is no easy task.
The Sculptor Dwarf Galaxy- also known as the Sculptor Dwarf Elliptical or the Sculptor Dwarf Spheroidal- is a dwarf spheroidal galaxy, and is one of the fourteen known satellite galaxies orbiting the Milky Way. These galactic hitchhikers are located close by in the Milky Way’s extensive halo, a spherical region extending far beyond our galaxy’s spiral arms. As indicated by its name, this galaxy is located in the southern constellation of Sculptor and lies about 280 000 light-years away from Earth. Despite its proximity, the galaxy was only discovered in 1937, as its stars are faint and spread thinly across the sky.
Although difficult to pick out, the Sculptor Dwarf Galaxy was among the first faint dwarf galaxies found orbiting the Milky Way. The tiny galaxy’s shape intrigued astronomers at the time of its discovery, but nowadays dwarf spheroidal galaxies play a more important role in allowing astronomers to dig deeply into the Universe’s past.
The Milky Way, like all large galaxies, is thought to have formed from the build-up of smaller galaxies during the early days of the Universe. If some of these small galaxies still remain today, they should now contain many extremely old stars. The Sculptor Dwarf Galaxy fits the bill as a primordial galaxy, thanks to a large number of ancient stars, visible in this image.
Astronomers can determine the age of stars in the galaxy because their light carries the signatures of only a small quantity of heavy chemical elements. These heavy elements accumulate in galaxies with successive generations of stars. A low level of heavy elements thus indicates that the average age of the stars in the Sculptor Dwarf Galaxy is high.
This quantity of old stars makes the Sculptor Dwarf Galaxy a prime target for studying the earliest periods of star formation. In a recent study, astronomers combined all the data available for the galaxy to create the most accurate star formation history ever determined for a dwarf spheroidal galaxy. This analysis revealed two distinct groups of stars in the galaxy. The first, predominant group is the older population, which is lacking in heavier elements. The second, smaller population, in contrast, is rich with heavy elements. Like young people crowding into city centres, this youthful stellar population is concentrated toward the galaxy’s core.
The stars within dwarf galaxies like the Sculptor Dwarf Galaxy can exhibit complex star formation histories. But as most of these dwarf galaxies’ stars have been isolated from each other and have not interacted for billions of years, each collection of stars has charted its own evolutionary course. Studying the similarities in dwarf galaxies’ histories, and explaining the occasional outliers, will help to explain the development of all galaxies, from the most unassuming dwarf to the grandest spirals. There is indeed much for astronomers to learn from the Milky Way’s shy neighbours.
[https://www.eso.org/public/usa/news/eso1536/]
Abell 2744, nicknamed Pandora’s Cluster, is a giant galaxy cluster resulting from the simultaneous pile-up of at least four separate, smaller galaxy clusters that took place over a span of 350 million years:
[https://en.wikipedia.org/wiki/Abell_2744]
Abell 2744: Pandora’s Cluster Revealed
A complex collision of at least four galaxy clusters is captured in this new image. Strange effects that have never been seen together before have apparently been produced because of this smash-up. This system has been dubbed ‘Pandora’s Cluster’ by astronomers because of all of the different structures found. Officially known as Abell 2744, this system is located about 3.5 billion light years from Earth.
One of the most complicated and dramatic collisions between galaxy clusters ever seen is captured in this new composite image. Data from NASA’s Chandra X-ray Observatory are colored red, showing gas with temperatures of millions of degrees. In blue is a map showing the total mass concentration (mostly dark matter) based on data from the Hubble Space Telescope (HST), the European Southern Observatory’s Very Large Telescope (VLT), and the Japanese Subaru telescope. Optical data from HST and VLT also show the constituent galaxies of the clusters.
The ‘core’ region shows a bullet-shaped structure in the X-ray emitting hot gas and a separation between the hot gas and the dark matter. (As a guide, local peaks in the distribution of hot gas and overall matter in the different regions are shown with red and blue circles respectively). This separation occurs because electric forces between colliding particles in the clouds of hot gas create a friction that slows them down, while dark matter is unaffected by such forces.
In the Northwest (‘NW’) region, a much larger separation is seen between the hot gas and the dark matter. Surprisingly, the hot gas leads the ‘dark’ clump (mostly dark matter) by about 500,000 light years. This unusual configuration may require a slingshot scenario, as suggested previously by scientists, to fling the hot gas ahead of the dark matter during an earlier interaction. In the North (‘N’) and the West (‘W’) two additional examples of hot gas separated from dark matter may be visible. The latter appears to exhibit the largest separation seen to date between hot gas and dark matter.
The authors of this study retraced the details of the collision, and deduce that at least four different galaxy clusters coming from a variety of directions were involved. To understand this history, it was crucial to map the positions of all three types of matter in Abell 2744. Although the galaxies are bright, they make up less than 5% of the mass in Abell 2744. The rest is hot gas (around 20%) visible only in X-rays, and dark matter (around 75%), which is completely invisible.
Dark matter is particularly elusive as it does not emit, absorb or reflect light, but only makes itself apparent through its gravitational attraction. To pinpoint the location of this mysterious substance the team used a phenomenon known as gravitational lensing. This is the bending of light rays from distant galaxies as they pass through the gravitational field present in the cluster. The result is a series of telltale distortions in the images of galaxies in the background of optical observations. By carefully plotting the way that these images are distorted, a map is constructed of where the mass -and hence the dark matter- actually lies (shown in blue).
Galaxy clusters are the largest gravitationally bound objects in the Universe and have become powerful tools in cosmology studies. Further studies of Abell 2744 may provide a deeper understanding of the way that these important objects grow and provide new insight into the properties of dark matter.
[http://chandra.harvard.edu/photo/2011/a2744/index.html]
[https://en.wikipedia.org/wiki/Sculptor_(constellation)]
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