A stubborn dwarf galaxy: The fuzzy collection of stars seen in this NASA/ESA Hubble Space Telescope image forms an intriguing dwarf galaxy named LEDA 677373, located about 14 million light-years away from us. Dwarf galaxies are small, faint collections of stars and gas. Their diverse properties make them intriguing objects to astronomers, but their small size means that we can only explore those that lie closest to us,  within the Local Group, such as LEDA 677373. This particular dwarf galaxy contains a plentiful reservoir of gas from which it could form stars. However, it stubbornly refuses to do so. In a bid to find out why, Hubble imaged the galaxy’s individual stars at different wavelengths, a method that allows astronomers to figure out a star’s age. These observations showed that the galaxy has been around for at least six billion years — plenty of time to form stars. So why has it not done so? Rather than being stubborn, LEDA 677373 seems to have been the unfortunate victim of a cosmic crime. A nearby giant spiral galaxy, Messier 83, seems to be stealing gas from the dwarf galaxy, stopping new stars from being born.

Name: LEDA 677373
Type: Local Universe : Galaxy : Size : Dwarf
Category: Galaxies
Constellation: Centaurus
Distance: 14 million light years
Release date: 4 July 2016, 06:00
Credit: ESA/Hubble & NASA

A lonely birthplace: This image was taken by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), and shows a starburst galaxy named MCG+07-33-027. This galaxy lies some 300 million light-years away from us, and is currently experiencing an extraordinarily high rate of star formation — a starburst. Normal galaxies produce only a couple of new stars per year, but starburst galaxies can produce a hundred times more than that! As MCG+07-33-027 is seen face-on, the galaxy’s spiral arms and the bright star-forming regions within them are clearly visible and easy for astronomers to study. In order to form newborn stars, the parent galaxy has to hold a large reservoir of gas, which is slowly depleted to spawn stars over time. For galaxies in a state of starburst, this intense period of star formation has to be triggered somehow — often this happens due to a collision with another galaxy. MCG+07-33-027, however, is special; while many galaxies are located within a large cluster of galaxies, MCG+07-33-027 is a field galaxy, which means it is rather isolated. Thus, the triggering of the starburst was most likely not due to a collision with a neighbouring or passing galaxy and astronomers are still speculating about the cause.

Name: MCG+07-33-027
Type: Local Universe : Galaxy : Type : Spiral
Category: Galaxies
Constellation: Hercules
Distance: 300 million light years
Release date: 11 July 2016, 06:00
Credit: ESA/Hubble & NASA and N. Grogin (STScI)

A galaxy fit to burst: This NASA/ESA Hubble Space Telescope image reveals the vibrant core of the galaxy NGC 3125. Discovered by John Herschel in 1835, NGC 3125 is a great example of a starburst galaxy — a galaxy in which unusually high numbers of new stars are forming, springing to life within intensely hot clouds of gas. Located approximately 50 million light-years away in the constellation of Antlia (The Air Pump), NGC 3125 is similar to, but unfathomably brighter and more energetic than, one of the Magellanic Clouds. Spanning 15 000 light-years, the galaxy displays massive and violent bursts of star formation, as shown by the hot, young, and blue stars scattered throughout the galaxy’s rose-tinted core. Some of these clumps of stars are notable — one of the most extreme Wolf–Rayet star clusters in the local Universe, NGC 3125-A1, resides within NGC 3125. Despite their appearance, the fuzzy white blobs dotted around the edge of this galaxy are not stars, but globular clusters. Found within a galaxy’s halo, globular clusters are ancient collections of hundreds of thousands of stars. They orbit around galactic centres like satellites — the Milky Way, for example, hosts over 150 of them.

Name: NGC 3125
Type: Local Universe : Galaxy : Activity : Starburst
Category: GalaxiesStars
Constellation: Antlia
Distance: 50 million light years
Release date: 18 July 2016, 06:00
Credit: ESA/Hubble & NASAAcknowledgement: Judy Schmidt (Geckzilla)

A long-dead star: This NASA/ESA Hubble Space Telescope image captures the remnants of a long-dead star. These rippling wisps of ionised gas, named DEM L316A, are located some 160 000 light-years away within one of the Milky Way’s closest galactic neighbours — the Large Magellanic Cloud (LMC). The explosion that formed DEM L316A was an example of an especially energetic and bright variety of supernova, known as a Type Ia. Such supernova events are thought to occur when a white dwarf star steals more material than it can handle from a nearby companion, and becomes unbalanced. The result is a spectacular release of energy in the form of a bright, violent explosion, which ejects the star’s outer layers into the surrounding space at immense speeds. As this expelled gas travels through the  interstellar material, it heats it up and ionise it, producing the faint glow that Hubble’s Wide Field Camera 3 has captured here. The LMC orbits the Milky Way as a satellite galaxy and is the fourth largest in our group of galaxies, the Local Group. DEM L316A is not alone in the LMC; Hubble came across another one in 2010 with SNR 0509 (heic1018), and in 2013 it snapped SNR 0519 (potw1317a).

Name: DEM L316A
Type: Milky Way : Nebula : Type : Supernova Remnant
Category: Nebulae
Constellation: Dorado
Distance: 150000 light years
Release date: 25 July 2016, 06:00
Credit: ESA/Hubble & NASA, Y. Chu

A sky full of stars: Located approximately 22 000 light-years away in the constellation of Musca (The Fly), this tightly packed collection of stars — known as a globular cluster — goes by the name of NGC 4833. This NASA/ESA Hubble Space Telescope image shows the dazzling stellar group in all its glory. NGC 4833 is one of the over 150 globular clusters known to reside within the Milky Way. These objects are thought to contain some of the oldest stars in our galaxy. Studying these ancient cosmic clusters can help astronomers to unravel how a galaxy formed and evolved, and give an idea of the galaxy’s age. Globular clusters are responsible for some of the most striking sights in the cosmos, with hundreds of thousands of stars congregating in the same region of space. Hubble has observed many of these clusters during its time in orbit around our planet, each as breathtaking as the last.

Name: NGC 4833
Type: Milky Way : Star : Grouping : Cluster : Globular
Category: Star Clusters
Constellation: Musca
Distance: 22000 light years
Release date: 1 August 2016, 06:00
Credit: ESA/Hubble and NASA