NGC 613 is a barred spiral galaxy located 67 million

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away in the southern

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Sculptor Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

. This galaxy was discovered in 1798 by German-English astronomer William Herschel, then re-discovered and catalogued by Scottish astronomer James Dunlop. It was first photographed in 1912, which revealed the spiral form of the nebula. During the twentieth century,

radio telescope A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency ...

observations showed that a linear feature in the nucleus was a relatively strong source of radio emission. NGC 613 is inclined by an angle of 37° to the line of sight from the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

along a position angle of 125°. The morphological classification of NGC 613 is SBbc(rs), indicating that it is a spiral galaxy with a bar across the nucleus (SB), a weak inner ring structure circling the bar (rs), and moderate to loosely wound spiral arms (bc). The bar is relatively broad but irregular in profile with a position angle that varies from 115–124° and dust lanes located along the leading edges. Star formation is occurring at the ends of the bar and extending along the well-defined spiral arms. The central bulge is readily apparent, with a radius of 14″. The classification of the nucleus is of type HII, indicating a match to the spectrum of an H II region. Near the core, the stars have a velocity dispersion of 136 ± 20 km/s. The nucleus is a source of radio emission with the form of an inner ring with a radius of about and a linear feature that is perhaps perpendicular to it. The latter consists of three discrete blobs spanning approximately . Observations suggest the presence of a supermassive black hole at the core with a mass in the range times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

. On September 20, 2016, Argentinian amateur astronomer Victor Buso captured supernova SN 2016gkg in NGC 613, just as it was starting to erupt. This was a type IIb

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

, a supernova that initially shows a hydrogen envelope like a

type II supernova A Type II supernova (plural: ''supernovae'' or ''supernovas'') results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, but no more than 40 to 50 times, the mass of the Sun () to undergo this ...

, but later loses the hydrogen lines in its spectrum to appear like a

type Ib supernova Type Ib and Type Ic supernovae are categories of supernovae that are caused by the stellar core collapse of massive stars. These stars have shed or been stripped of their outer envelope of hydrogen, and, when compared to the spectrum ...

. It showed the double peak that is common to many type IIb supernovae, rising to around magnitude 15.5 shortly after discovery and then again about 20 days later. The progenitor star has been identified in

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

images from before its collapse, and it is likely to have been a

yellow supergiant A yellow supergiant (YSG) is a star, generally of spectral type F or G, having a supergiant luminosity class (e.g. Ia or Ib). They are stars that have evolved away from the main sequence, expanding and becoming more luminous. Yellow supergiants ...

References

Gallery

Sculpted_in_Sculptor.jpg, First discovered in 1798 by German-English astronomer William Hershel, NGC 613 is a galaxy which lies in the southern constellation of Sculptor 67 million light-years away. .

External links

Supernova SN 2016gkg in NGC 613
from The Virtual Telescope Project {{DEFAULTSORT:NGC 613 Sculptor (constellation) Barred spiral galaxies 0613 005849