M80No, not the firecracker, the star cluster.

M80 is in the constellation Scorpius between the stars α Scorpii (Antares) and β Scorpii in a part of the Milky Way rich in nebulae. When viewed with a modest amateur telescope (like mine), it appears as a mottled ball of light. This Hubble image shows more detail. M80 is roughly 95 light-years in diameter. It contains several hundred thousand stars, making it one of the more densely populated globular clusters in the galaxy.

M80 contains a fair number of blue stragglers, stars that appear to be much younger than the cluster itself. Astronomers believe that these stars lost part of their outer layers during close encounters with other cluster members or as the result of collisions between stars in the tightly packed cluster. Images from Hubble show regions with very high blue straggler densities which suggests that the center of the cluster probably has a very high capture and collision rate.

Image Credit: NASA / ESA

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

The Monkey Head Nebula

Monkey HeadThe Hubble Space Telescope captured a series of infrared-light images of a churning region of star birth 6,400 light-years away some of which have been stitched together in this mosaic of a small portion of the Monkey Head Nebula The cloud is sculpted by ultraviolet light eating into the cool hydrogen gas.

Image Credit: NASA / ESA

A Glory on Venus

Venus_glory_largeA rainbow-like feature known as a “glory” has been seen by ESA’s Venus Express orbiter in the atmosphere of our nearest planetary neighbor—the first time one has been fully imaged on another planet.

Rainbows and glories occur when sunlight shines on cloud droplets—water particles here on Earth. While rainbows arch across the sky, glories are typically much smaller and are made up of a series of coloured concentric rings centred on a bright core. Glories are only seen when the observer is situated directly between the Sun and the cloud particles that are reflecting sunlight. On Earth, they are often seen from aircraft, surrounding the shadow of the aircraft on the clouds below.

In order for a glory to occur, the particles must be spherical and the same size. The atmosphere of Venus is thought to contain droplets rich in sulphuric acid.

Mission scientists at ESA hoped to find a glory in the atmosphere of Venus by imaging the clouds with the Sun directly behind the Venus Express spacecraft. They were successful. The glory in this image was seen at the Venus cloud tops, 70 km above the planet’s surface. It is 1,200 km wide as seen from the spacecraft, 6,000 km away.

Image Credit: ESA

The Fireworks Galaxy

NGC 6946 is known as the Fireworks Galaxy, In the past century, nine supernovae have been observed to explode in its spiral arms. This makes it the most prolific known galaxy for this type of event over a period of 100 years. By comparison, the Milky Way galaxy, which has twice as many stars as NGC 6946, averages one supernova event per century.

Image Credits: NASA, ESA, STScI, R. Gendler, and the Subaru Telescope (NAOJ)

Caldwell 90

Caldwell 90 is a planetary nebula formed in the late stages of the life of a Sun-like star. Initially, the star’s energy was derived by fusing hydrogen into helium. When the supply of hydrogen ran low, it produced less energy, so the force of gravity caused it to contract. Eventually, that contraction increased the pressure in the star’s core and triggered fusion of the heavier element carbon. That process caused the star to expand into a red giant. Finally, the red giant’s outer layers were eject to form the nebula and the star collapsed again into a small, dense star whose intense radiation continues to push the nebula boundaries outward.

The Sun will probably go through a similar process in 4 or 5 billion years.

Image Credit: NASA / ESA

NGC 4689

NGC 4689 is a spiral galaxy located about 54 million light-years away in the constellation of Coma Berenices and a member of the Virgo Cluster of galaxies.

The galaxy’s star forming disk has been truncated which has caused the amount of star formation to be significantly reduced. The truncation may have been the result of interaction with other galaxies in the Virgo Cluster which caused the galaxy to lose much of its interstellar gas and dust, the fuel for new star formation. NGC 4689 has been classified as an Anemic galaxy because its lack of material for making new stars.

Image Credit: NASA / ESA

Lonely Dwarfs

Luhman 16AB is a double star system composed of two brown dwarfs. It’s only about six light-years away, and is the third closest stellar system to Earth—after the triple star system Alpha Centauri and Barnard’s Star. Because the brown dwarfs are so dim, Luhman 16AB was only discovered in 2013.

This series of dots with varying spacings between them in the image above shows the slow waltz of the two brown dwarfs. It’s a composite of 12 images made over the course of three years by the Hubble Space Telescope. Using high-precision astrometry, a team of astronomers tracked the two components of the system as they moved both across the sky and around each other.

The brown dwarfs, Luhman 16A and Luhman 16B, orbit each other at a distance of only about 500,000,000 km, roughly three times the distance between the Earth and the Sun. Observations of the system require high resolution. The astronomers using Hubble to study Luhman 16AB were not only interested in the waltz of the two stars as they orbited each other but also were also searching for a third, invisible partner. Earlier ground-based observation suggested the presence of an exoplanet in the system, but the Hubble data showed that the two dwarfs are indeed dancing alone, unperturbed by a massive planetary companion.

Image Credit: NASA / ESA

NGC 3447

Some galaxies are hard to classify. The more diffuse and patchy blue glow covering the right side of the image above is known as NGC 3447B. The smaller clump to the upper left is known as NGC 3447A. The pair are know collectively as NGC 3447.

The two are so close that they are strongly influenced and distorted by the gravitational forces between them, causing the galaxies to twist themselves into unusual  shapes seen here. Astronomers are unsure what the originals shapes of the two galaxies were before they encountered each other. NGC 3447A appears to display the remnants of a central bar structure and some disrupted spiral arms, both properties characteristic of certain spiral galaxies. NGC 3447B may also have been spiral galaxy, or it may have been an irregular galaxy.

Image Credit: NASA / ESA

NGC 5364

Despite being classified ias a grand spiral galaxy, NGC 5364 is far from perfect. Its arms are asymmetrical compared to other grand design spirals. This is probably caused by interactions with a neighboring galaxy. This neighbor and NGC 5364 are pulling on one another, moving their stars and gas around. Thus, NGC 5364’s misshapen appearance.

Image Credit: NASA / ESA