Category: galaxy classification

Lenticular Galaxy NGC 4111

by warrenh, posted in astronomy, astronomy news, astronomy questions, elliptical galaxies, entertainment, ESA, galaxies, Hubble Space Telescope, Hubble Tuning Fork, lenticular galaxies, NGC 4111

Lens-shaped galaxies have characteristics astronomers see in elliptical and spiral galaxies

The elegant simplicity of NGC 4111, seen here in this image from the NASA/ESA Hubble Space Telescope, hides a more violent history than you might think. NGC 4111 is a lenticular, or lens-shaped, galaxy, lying about 50 million light-years from us in the constellation of Canes Venatici (The Hunting Dogs). Lenticular galaxies are an intermediate type of galaxy between an elliptical and a spiral. They host aged stars like ellipticals and have a disk like a spiral. However, that’s where the similarities end: they differ from ellipticals because they have a bulge and a thin disk, but are different from spirals because lenticular discs contain very little gas and dust, and do not feature the many-armed structure that is characteristic of spiral galaxies. In this image we see the disc of NGC 4111 edge-on, so it appears as a thin sliver of light on the sky. At first sight, NGC 4111 looks like a fairly uneventful galaxy, but there are unusual features that suggest it is not such a peaceful place. Running through its centre, at right angles to the thin disc, is a series of filaments, silhouetted against the bright core of the galaxy. These are made of dust, and astronomers think they are associated with a ring of material encircling the galaxy’s core. Since it is not aligned with the galaxy’s main disc, it is possible that this polar ring of gas and dust is actually the remains of a smaller galaxy that was swallowed up by NGC 4111 long ago.
The elegant simplicity of NGC 4111, seen here in this image from the NASA/ESA Hubble Space Telescope. 

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 seen in 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 material orbiting 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. 

Learn more about the Hubble Tuning Fork.

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Read more about lenticular galaxies.

Read about the stellar object called the Red Rectangle, star system HD 44179.

Learn more about TESS, the next generation planet hunter.

Read about astronomers observing the merging of two galaxies into galaxy NGC 6052.

Lenticular Galaxy Mrk 820

by warrenh, posted in astronomy, astronomy information, astronomy news, Bootes, entertainment, galaxies, galaxy classification, Hubble Tuning Fork, Mrk 820

Hints of a spiral structure embedded in a circular halo of stars

Sprinkled throughout this stunning image are numerous examples of almost every type of galaxy on the Hubble Tuning Fork. Almost all of the light smears and specks viewed are distant galaxies astronomers study in order to delve deeper into the mysteries of the evolution of these islands of stars.
Sprinkled throughout this stunning image are numerous examples of almost every type of galaxy on the Hubble Tuning Fork. Almost all of the light smears and specks viewed are distant galaxies astronomers study in order to delve deeper into the mysteries of the evolution of these islands 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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Read about swirls detected forming in the disk of dust surrounding infant suns.

Read about mysterious ripples detected moving across the planet forming region of a distant, young sun.

Read about US congress recognizing right of US citizens to own asteroid resources.