Swimming in Sculptor: Peering deep into the early Universe, this picturesque parallel field observation from the NASA/ESA Hubble Space Telescope reveals thousands of colourful galaxies swimming in the inky blackness of space. A few foreground stars from our own galaxy, the Milky Way, are also visible. In October 2013 Hubble’s Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS) began observing this portion of sky as part of the Frontier Fields programme. This spectacular skyscape was captured during the study of the giant galaxy cluster Abell 2744, otherwise known as Pandora’s Box. While one of Hubble’s cameras concentrated on Abell 2744, the other camera viewed this adjacent patch of sky near to the cluster. Containing countless galaxies of various ages, shapes and sizes, this parallel field observation is nearly as deep as the Hubble Ultra-Deep Field. In addition to showcasing the stunning beauty of the deep Universe in incredible detail, this parallel field — when compared to other deep fields — will help astronomers understand how similar the Universe looks in different directions

Name: Abell 2744
Type: Local Universe : Cosmology : Morphology : Deep Field
Category: Galaxies
Constellation: Sculptor
Release date: 7 March 2016, 06:00
Credit: NASA, ESA and the HST Frontier Fields team (STScI) Acknowledgement: Judy Schmidt (Geckzilla)

Disco lights from a galaxy cluster: In October of 2013 Hubble kicked off the Frontier Fields programme, a three-year series of observations aiming to produce the deepest ever views of the Universe. The project’s targets comprise six massive galaxy clusters, enormous collections of hundreds or even thousands of galaxies. These structures are the largest gravitationally-bound objects in the cosmos. One of the Frontier Fields targets is shown in this new image: MACS J0717.5+3745, or MACS J0717 for short. MACS J0717 is located about 5.4 billion light-years away from Earth, in the constellation of Auriga (The Charioteer). It is one of the most complex galaxy clusters known; rather than being a single cluster, it is actually the result of four galaxy clusters colliding. This image is a combination of observations from the NASA/ESA Hubble Space Telescope (showing the galaxies and stars), the NASA Chandra X-ray Observatory (diffuse emission in blue), and the NRAO Jansky Very Large Array (diffuse emission in pink). The Hubble data were collected as part of the Frontier Fields programme mentioned above. Together, the three datasets produce a unique new view of MACS J0717. The Hubble data reveal galaxies both within the cluster and far behind it, and the Chandra observations show bright pockets of scorching gas — heated to millions of degrees. The data collected by the Jansky Very Large Array trace the radio emission within the cluster, enormous shock waves — similar to sonic booms — that were triggered by the violent merger. For more information on Frontier Fields, see Hubblecast 90: The final frontier.

Name: MACS J0717.5+3745
Type: Early Universe : Galaxy : Grouping : ClusterEarly Universe : Cosmology : Phenomenon : Lensing
Category: Cosmology
Constellation: Auriga
Distance: 6 billion light years
Release date: 14 March 2016, 06:00
Credit: NASA, ESA, CXC, NRAO/AUI/NSF, STScI, and R. van Weeren (Harvard-Smithsonian Center for Astrophysics) Acknowledgment: NASA, ESA, and J. Lotz (STScI), and the HFF team

A cosmic kaleidoscope: At first glance, this cosmic kaleidoscope of purple, blue and pink offers a strikingly beautiful — and serene — snapshot of the cosmos. However, this multi-coloured haze actually marks the site of two colliding galaxy clusters, forming a single object known as MACS J0416.1-2403 (or MACS J0416 for short). MACS J0416 is located about 4.3 billion light-years from Earth, in the constellation of Eridanus. This new image of the cluster combines data from three different telescopes: the NASA/ESA Hubble Space Telescope (showing the galaxies and stars), the NASA Chandra X-ray Observatory (diffuse emission in blue), and the NRAO Jansky Very Large Array (diffuse emission in pink). Each telescope shows a different element of the cluster, allowing astronomers to study MACS J0416 in detail. As with all galaxy clusters, MACS J0416 contains a significant amount of dark matter, which leaves a detectable imprint in visible light by distorting the images of background galaxies. In this image, this dark matter appears to align well with the blue-hued hot gas, suggesting that the two clusters have not yet collided; if the clusters had already smashed into one another, the dark matter and gas would have separated. MACS J0416 also contains other features — such as a compact core of hot gas — that would likely have been disrupted had a collision already occurred. Together with five other galaxy clusters, MACS J0416 is playing a leading role in the Hubble Frontier Fields programme, for which this data was obtained. Owing to its huge mass, the cluster is in fact bending the light of background objects, acting as a magnifying lens. Astronomers can use this phenomenon to find galaxies that existed only hundreds of million years after the big bang. For more information on both Frontier Fields and the phenomenon of gravitational lensing, see Hubblecast 90: The final frontier.

Name: MACS J0416.1-2403
Type: Early Universe : Galaxy : Grouping : ClusterEarly Universe : Cosmology : Phenomenon : Lensing
Category: Cosmology
Constellation: Eridanus
Distance: 4 billion light years
Release date: 21 March 2016, 06:00
Credit: NASA, ESA, CXC, NRAO/AUI/NSF, STScI, and G. Ogrean (Stanford University) Acknowledgment: NASA, ESA, and J. Lotz (STScI), and the HFF team

A distinctly disorganised dwarf: Despite being less famous than their elliptical and spiral galactic cousins, irregular  dwarf galaxies, such as the one captured in this NASA/ESA Hubble Space Telescope image, are actually one of the most common types of galaxy in the Universe. Known as UGC 4459, this dwarf galaxy is located approximately 11 million light-years away in the constellation of Ursa Major (The Great Bear), a constellation that is also home to the Pinwheel Galaxy (M101), the Owl Nebula (M97), Messier 81, Messier 82 and  several other galaxies all part of the M81 group. UGC 4459’s diffused and disorganised appearance is characteristic of an irregular dwarf galaxy. Lacking a distinctive structure or shape, irregular dwarf galaxies are often chaotic in appearance, with neither a nuclear bulge — a huge, tightly packed central group of stars — nor any trace of spiral arms — regions of stars extending from the centre of the galaxy. Astronomers suspect that some irregular dwarf galaxies were once spiral or elliptical galaxies, but were later deformed by the gravitational pull of nearby objects. Rich with young blue stars and older red stars, UGC 4459 has a stellar population of several billion. Though seemingly impressive, this is small when compared to the  200 to 400 billion stars in the Milky Way! Observations with Hubble have shown that because of their low masses, star formation is very low compared to larger galaxies. Only very little of their original gas has been turned into stars. Thus, these small galaxies are interesting to study to better understand primordial environments and the star formation process.

Name: UGC 4459
Type: Local Universe : Galaxy : Size : Dwarf
Category: Galaxies
Constellation: Ursa Major
Distance: 11 million light years
Release date: 28 March 2016, 06:00
Credit: ESA/Hubble & NASA Acknowledgement: Judy Schmidt (Geckzilla)