An Umbrella and a Dwarf


NGC 4651 is a spiral galaxy located in the constellation of Coma Berenices. It’s a member of the Virgo Cluster and is known as the Umbrella Galaxy because of the umbrella-shaped structure extending from its disk composed of stellar streams that are the remnants of a much smaller galaxy that’ been torn apart by NGC 4651’s tidal forces. Studies using radio telescopes show distortions on NGC 4651’s outer regions and a gas clump associated with a dwarf galaxy that may have born in the event that produced those stellar streams.

Image Credit: NASA / ESA

Cool Andromeda


Cool_AndromedaThis view of the Andromeda galaxy from the Herschel space observatory shows relatively cool lanes of forming stars. Herschel was sensitive to the far-infrared light from cool dust mixed in with the gas where stars are born. This image reveals some of the very coldest dust in the galaxy (colored red here) that is only a few tens of degrees above absolute zero. Warmer regions such as the densely populated central bulge, home to older stars, appear as blue. Star-formation zones are in the spiral arms with several concentric rings interspersed with dark gaps where star formation is absent.

Andromeda (aka M31) is the nearest major galaxy to our own Milky Way about 2.5 million light-years away. Herschel was a European Space Agency mission active from 2009 to 2013.

Image Credit: ESA

A Seyfert Galaxy


NGC 5793Carl Seyfert was an interesting fellow. Back in the ’50s when I was a kid growing up in Nashville, he was Director of the Dyer Observatory at Vanderbilt University. I met him through the local astronomy club associated with the Nashville Children’s Museum. He was well known around town because he moonlighted as the weatherman for WSM-TV. He was known in astronomical circles for his research on a class of galaxies.

Those galaxies have incredibly luminous centers that we believe are caused by supermassive black holes—black holes that can be billions of times the mass of the sun—pulling in and swallowing gas and dust from their surroundings. NGC 5793 is a Seyfert galaxy over 150 million light-years away in the constellation of Libra.

This Hubble image is centered on NGC 5793. This galaxy is of great interest to astronomers for many reasons. For one, it appears to house objects known as masers. Whereas lasers emit visible light, masers emit microwave radiation. The term “maser” is an acronym of Microwave Amplification by Stimulated Emission of Radiation. Lasers emit visible light; masers emit microwave radiation. Maser emission occurs when particles absorb energy from their surroundings re-emit the energy in the microwave part of the spectrum. Naturally occurring masers such as are found in NGC 5793 can tell us a lot about their environment; we see some types of masers in areas where stars are forming. In NGC 5793 there are also intense mega-masers, thousands of times more luminous than the sun.

Image Credit: NASA / ESA

Westerlund 1


This is a young super star cluster known as Westerlund 1. It’s the home of one of the largest stars yet found. Westerlund 1-26 is a red supergiant with a radius over 1,500 times that of our sun. Indeed, it’s sometimes referred to as a hypergiant star. If Westerlund 1-26 were at the center of our solar system, it would extend out beyond the orbit of Jupiter.

The Westerlund 1 cluster is relatively young in astronomical terms, around three million years old. The Sun is around 4.6 billion years old.

Image Credit: NASA / ESA

The Orion Nebula in False Color


This false color image of the Orion Nebula was generated using visible light and infrared data from two of the instruments onboard the Hubble Space Telescope. The image shows a segment of the sky about 0.002° wide. That works out to around 3.4 light-years at the nebula which is 1,500 light-years away.

Image Credit: Nasa / ESA / STScI