Space news (lenticular galaxies) – 100 million light-years from Earth in the constellation Ursa Major (The Great Bear) –
Thegalaxy seen here is NGC 5308, a typical lenticular galaxy swarmed by star clusters circling around itlike bees around a beehive. The Hubble Space Telescope image seen hereis edge-on in relation to the galaxy, which offers a great view of the halo formed by thedense collection of older starsorbiting this island universe.
Edge-on lenticular galaxies like NGC 5308 are S0 on the Hubble Tuning Fork classification system and are considereda transitional type betweenelliptical and spiral galaxies. But scientists are still trying to figure out the right formation theory for this type of galaxy. We’ll talk more about the current lenticular galaxy formation theory in a later article.
Also known as LEDA 48860 and UGC 8722, galaxies like this island universe are often referred to as armless spiral galaxies by astronomers. They usually have no obvious structure in their disks and are composed primarily of older, red stars. Lenticular galaxies like NGC 5308 often also appear more like elliptical galaxies than spirals, but usually have more dust.
Lenticular galaxies can often be mistaken for EO type galaxies if their central bulge isn’t very bright. Theyalso don’t have spiral arms alive with bright, young stars as observed in spiral galaxies. But arefound in some cases with a bar and in this case areclassified as a barred lenticular galaxy (SBO).
Lens-shaped galaxies have characteristics astronomers see in elliptical and spiral galaxies
Space news (lenticular galaxies) – 50 million light-years from Earth, in the constellation of Canes Venatici (The Hunting Dogs) –
This Hubble Space Telescope image of lenticular galaxy NGC 4111 shows an island universe with a more chaotic past than first thought. Lenticular or lens-shaped galaxies are labelled S0 on the Hubble Tuning Fork and are classified as a transitional type between spiral and elliptical galaxies.
Lenticular galaxies host older stars as observed in elliptical galaxies and include a disc as seenin spiral galaxies. However, they have a bulge and thin disc, which hasn’t been observed in elliptical galaxies. They also don’t have arms and the gas and dust detected in spiral galaxies.
NGC 4111 appears as a thin sliver of lights in this image because Hubble’s viewing the edge of the galaxy. At first glance, this island universe looks relatively quiet, but there are regions suggesting a more chaotic past. Pillars of dark filaments silhouetted against the bright core of the galaxy and running through the centre at right angles to the thin disc. Dark filaments of dust and gas astronomers associate with a ring of materialorbiting its core.
This ring of orbiting material isn’t aligned with the main disc of NGC 4111, which has astrophysicists thinking it could be the remains of a smaller galaxy it collided with long ago. Considering the possible mass and volume of this past meal, indigestion probably isn’t unexpected.
Hints of a spiral structure embedded in a circular halo of stars
Space news (February 1, 2016) – 300 million light-years away in the Bootes constellation –
Astronomers use the Hubble Tuning Fork to classify galaxies viewed during the human journey to the beginning of space and time according to their morphology. Devised by noted astronomer Edwin Hubble during the early part of the twentieth century, this galaxy classification system breaks galaxies into two general categories; elliptical and spiral galaxies.
Island universes viewed that don’t seem to fit into the two general categories of galaxies are considered irregular galaxies. Irregular galaxies have a more varied look than the general categories, often with a spiral structure that looks disturbed or disrupted. It’s this disrupted structure, and other hints, that makes astronomers think the more chaotic and varied look of these island universes could often be due to titanic collisions between galaxies.
The galaxy viewed in the image above is Mrk 820 (also LEDA 52404 or IRAS F14379+3142), a lenticular galaxy in the transition zone between the two general categories of galaxies (Type S0). Astronomers looking closer at his spectacular island universe believe it shows hints of spiral arms imprinted on a halo of stars, which is unusual for lenticular galaxies. Lenticular galaxies generally have a notable central bulge and disk, but no spiral arms.
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