Skip to main content

A Spiral Snowflake


Image: The spiral galaxy NGC 6814. Credit:
ESA/Hubble & NASA. Acknowledgement: Judy Schmidt (Geckzilla)

Spiral galaxies together with irregular galaxies make up approximately 60% of the galaxies in the local Universe. However, despite their prevalence, each spiral galaxy is unique - like snowflakes, no two are alike. This is demonstrated by the striking face-on spiral galaxy NGC 6814, whose luminous nucleus and spectacular sweeping arms, rippled with an intricate pattern of dark dust, are captured in this NASA/ESA Hubble Space Telescope image.

NGC 6814 has an extremely bright nucleus, a telltale sign that the galaxy is a Seyfert galaxy.

Seyfert galaxies account for about 10% of all galaxies and are some of the most intensely studied objects in astronomy, as they are thought to be powered by the same phenomena that occur in quasars, although they are closer and less luminous than quasars. These galaxies have supermassive black holes at their centers which are surrounded by accretion discs of in-falling material. The accretion discs are believed to be the source of the observed ultraviolet radiation. Ultraviolet emission and absorption lines provide the best diagnostics for the composition of the surrounding material.

Seen in visible light, most Seyfert galaxies look like normal spiral galaxies, but when studied under other wavelengths, it becomes clear that the luminosity of their cores is of comparable intensity to the luminosity of whole galaxies the size of the Milky Way.

The luminous heart of NGC 6814 is a highly variable source of X-ray radiation, causing scientists to suspect that it hosts a supermassive black hole with a mass about 18 million times that of the Sun.

As NGC 6814 is a very active galaxy, many regions of ionised gas are studded along  its spiral arms. In these large clouds of gas, a burst of star formation has recently taken place, forging the brilliant blue stars that are visible scattered throughout the galaxy.

Links

Etichette:

Comments

Post a Comment

Popular posts from this blog

SUPERNOVAE FROM WD-WD DIRECT COLLISIONS

Image: Supernova remnant N 63A. Credit: NASA/ESA/HEIC and The Hubble Heritage Team (STScI/AURA) Models for supernovae (SNe) related to thermonuclear explosions of white dwarfs (WDs) have been extensively studied over the last few decades, mostly focusing on single degenerate (accretion of material of a WD) and double degenerate (WD-WD merger) scenarios.
Post a Comment
Read more

Atmospheric Beacons Guide NASA Scientists in Search for Life

Beacons of life could help researchers identify potentially habitable worlds. Credits: NASA’s Goddard Space Flight Center/Mary Pat Hrybyk Some exoplanets shine brighter than others in the search for life beyond the solar system. New NASA research proposes a novel approach to sniffing out exoplanet atmospheres. It takes advantage of frequent stellar storms — which hurl huge clouds of stellar material and radiation into space — from cool, young dwarf stars to highlight signs of habitable exoplanets. Traditionally, researchers have sought potential biosignatures as ways of identifying inhabited worlds: byproducts from life as we know it such as oxygen or methane that over time accumulate in the atmosphere to detectable amounts. But with current technology, according to Vladimir Airapetian, lead author of a Nature Scientific Reports study published on Nov. 2, 2017, identifying these gases on distant terrestrial exoplanets is time-consuming, requiring days of observation time. The ne...
Post a Comment
Read more

ABOUT THE FORMATION OF THE COLD CLASSICAL KUIPER BELT

Image: The Kuiper Belt. Credit: NASA . The Kuiper belt is a circumstellar disc in the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt (the circumstellar disc located roughly between the orbits of the planets Mars and Jupiter), but it is far larger-20 times as wide and 20 to 200 times as massive.
2 comments
Read more