October 6, 2017

4LGSF on UT4 of the VLT at ESO's Paranal Observatory

4LGSF on UT4 of the VLT at ESO's Paranal Observatory

The 4 Laser Guide Star Facility (4LGSF), a new subsystem of the Adaptive Optics Facility (AOF) on UT4 of the Very Large Telescope (VLT), at ESO's Paranal Observatory in Chile. The facility saw first light in April 2016 and is the most powerful laser guide star system in the world. The image was taken by ESO Photo Ambassador Juan Carlos Muñoz-Mateos.

Image Credit: Juan Carlos Muñoz-Mateos/ESO
Explanation from: https://www.eso.org/public/images/ut4_4lasers-cc/

Large Magellanic Cloud Galaxy in the Infrared

Large Magellanic Cloud Galaxy in the Infrared

This vibrant image from NASA's Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy.

The infrared image, a mosaic of 300,000 individual tiles, offers astronomers a unique chance to study the lifecycle of stars and dust in a single galaxy. Nearly one million objects are revealed for the first time in this Spitzer view, which represents about a 1,000-fold improvement in sensitivity over previous space-based missions. Most of the new objects are dusty stars of various ages populating the Large Magellanic Cloud; the rest are thought to be background galaxies.

The blue color in the picture, seen most prominently in the central bar, represents starlight from older stars. The chaotic, bright regions outside this bar are filled with hot, massive stars buried in thick blankets of dust. The red color around these bright regions is from dust heated by stars, while the red dots scattered throughout the picture are either dusty, old stars or more distant galaxies. The greenish clouds contain cooler interstellar gas and molecular-sized dust grains illuminated by ambient starlight.

Astronomers say this image allows them to quantify the process by which space dust the same stuff that makes up planets and even people is recycled in a galaxy. The picture shows dust at its three main cosmic hangouts: around the young stars, where it is being consumed (red-tinted, bright clouds); scattered about in the space between stars (greenish clouds); and in expelled shells of material from old stars (randomly-spaced red dots).

The Large Magellanic Cloud, located 160,000 light-years from Earth, is one of a handful of dwarf galaxies that orbit our own Milky Way. It is approximately one-third as wide as the Milky Way, and, if it could be seen in its entirety, would cover the same amount of sky as a grid of about 480 full moons. About one-third of the entire galaxy can be seen in the Spitzer image.

This picture is a composite of infrared light captured by Spitzer. Light with wavelengths of 3.6 (blue) and 8 (green) microns was captured by the telescope's infrared array camera; 24-micron light (red) was detected by the multiband imaging photometer.

Image Credit: NASA/JPL-Caltech/M. Meixner (STScI) & the SAGE Legacy Team
Explanation from: http://www.spitzer.caltech.edu/images/1670-ssc2006-17b1-Large-Magellanic-Cloud-in-the-Infrared

Jupiter seen by NASA's Juno spacecraft

Jupiter seen by NASA's Juno spacecraft

This striking image of Jupiter was captured by NASA's Juno spacecraft as it performed its eighth flyby of the gas giant planet.

The image was taken on September 1, 2017 at 2:58 p.m. PDT (5:58 p.m. EDT). At the time the image was taken, the spacecraft was 4,707 miles (7,576 kilometers) from the tops of the clouds of the planet at a latitude of about -17.4 degrees.

Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstadt
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21966

October 5, 2017

Aurora over Canada seen from the International Space Station

Aurora over Canada seen from the International Space Station

The spectacular aurora borealis, or the “northern lights,” over Canada is sighted from the International Space Station near the highest point of its orbital path. The station’s main solar arrays are seen in the left foreground. This photograph was taken by a member of the Expedition 53 crew aboard the station on September 15, 2017.

Image Credit: NASA
Explanation from: https://www.nasa.gov/image-feature/northern-lights-over-canada-0

Comet C/2017 K2 (PANSTARRS)

Comet C/2017 K2 (PANSTARRS)

This Hubble Space Telescope image shows a fuzzy cloud of dust, called a coma, surrounding the comet C/2017 K2 PANSTARRS (K2), the farthest active comet ever observed entering the solar system. Hubble snapped images of K2 when the frozen visitor was over 2.4 billion kilometres from the Sun, just beyond Saturn's orbit. Even at that remote distance, sunlight is warming the frigid comet, producing a 128,000-kilometre-wide coma that envelops a tiny, solid nucleus. K2 has been traveling for millions of years from its home in the Oort Cloud, a spherical region at the edge of our solar system. This frigid area contains hundreds of billions of comets, the icy leftovers from the formation of the solar system 4.6 billion years ago. The image was taken in June 2017 by Hubble's Wide Field Camera 3.

Image Credit: NASA, ESA, and D. Jewitt (UCLA)
Explanation from: https://www.spacetelescope.org/images/opo1740a/

Spiral Galaxy NGC 6753

Spiral Galaxy NGC 6753

Despite the advances made in past decades, the process of galaxy formation remains an open question in astronomy. Various theories have been suggested, but since galaxies come in all shapes and sizes — including elliptical, spiral, and irregular — no single theory has so far been able to satisfactorily explain the origins of all the galaxies we see throughout the Universe.

To determine which formation model is correct (if any), astronomers hunt for the telltale signs of various physical processes. One example of this is galactic coronas, which are huge, invisible regions of hot gas that surround a galaxy’s visible bulk, forming a spheroidal shape. They are so hot that they can be detected by their X-ray emission, far beyond the optical radius of the galaxy. Because they are so wispy, these coronas are extremely difficult to detect. In 2013, astronomers highlighted NGC 6753, imaged here by the NASA/ESA Hubble Space Telescope, as one of only two known spiral galaxies that were both massive enough and close enough to permit detailed observations of their coronas. Of course, NGC 6753 is only close in astronomical terms — the galaxy is nearly 150 million light-years from Earth.

NGC 6753 is a whirl of colour in this image — the bursts of blue throughout the spiral arms are regions filled with young stars glowing brightly in ultraviolet light, while redder areas are filled with older stars emitting in the cooler near-infrared.

Image Credit: ESA/Hubble & NASA, Judy Schmidt
Explanation from: https://www.spacetelescope.org/images/potw1738a/

October 2, 2017

Tungurahua Volcano Eruption

Tungurahua Volcano Eruption

Tungurahua, Ecuador

Image Credit: Sebastián Crespo

Spiral Galaxy NGC 1964

Spiral Galaxy NGC 1964

This spectacular spiral galaxy, known as NGC 1964, resides approximately 70 million light-years away in the constellation of Lepus (The Hare). NGC 1964 has a bright and dense core. This core sits within a mottled oval disc, which is itself encircled by distinct spiral arms speckled with bright starry regions. The brilliant centre of the galaxy caught the eye of the astronomer William Herschel on the night of 20 November 1784, leading to the galaxy’s discovery and subsequent documentation in the New General Catalogue.

In addition to containing stars, NGC 1964 lives in a star-sprinkled section of the sky. In this view from the Wide Field Imager (WFI) — an instrument mounted on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory, Chile — the star HD 36785 can be seen to the galaxy’s immediate right. Above it reside two other prominent stars named HD 36784 and TYC 5928-368-1 — and the large bright star below NGC 1964 is known as BD-22 1147.

This view of NGC 1964 also contains an array of galaxies, visible in the background. The WFI is able to observe the light from these distant galaxies, and those up to 40 million times fainter than the human eye can see.

Image Credit: ESO/Jean-Christophe Lambry
Explanation from: https://www.eso.org/public/images/potw1739a/

Star-Forming Regions in the Large Magellanic Cloud Galaxy

Star-Forming Regions in the Large Magellanic Cloud Galaxy

At a distance of just 160 000 light-years, the Large Magellanic Cloud (LMC) is one of the Milky Way’s closest companions. It is also home to one of the largest and most intense regions of active star formation known to exist anywhere in our galactic neighbourhood — the Tarantula Nebula. This NASA/ESA Hubble Space Telescope image shows both the spindly, spidery filaments of gas that inspired the region’s name, and the intriguing structure of stacked “bubbles” that forms the so-called Honeycomb Nebula (to the lower left).

The Honeycomb Nebula was found serendipitously by astronomers using ESO’s New Technology Telescope to image the nearby SN1987A, the closest observed supernova to Earth for over 400 years. The nebula’s strange bubble-like shape has baffled astronomers since its discovery in the early 1990s. Various theories have been proposed to explain its unique structure, some more exotic than others.

In 2010, a group of astronomers studied the nebula and, using advanced data analysis and computer modelling, came to the conclusion that its unique appearance is likely due to the combined effect of two supernovae — a more recent explosion has pierced the expanding shell of material created by an older explosion. The nebula’s especially striking appearance is suspected to be due to a fortuitous viewing angle; the honeycomb effect of the circular shells may not be visible from another viewpoint.

Image Credit: ESA/Hubble & NASA, Judy Schmidt
Explanation from: https://www.spacetelescope.org/images/potw1740a/

October 1, 2017

Tungurahua Volcano Eruption

Tungurahua Volcano Eruption

Tungurahua, Ecuador

Image Credit: Per-Andre Hoffmann

Spiral Galaxy NGC 4490

Spiral Galaxy NGC 4490

This oddly-shaped galactic spectacle is bursting with brand new stars. The pink fireworks in this image taken with the NASA/ESA Hubble Space Telescope are regions of intense star formation, triggered by a cosmic-scale collision. The huge galaxy in this image, NGC 4490, has a smaller galaxy in its gravitational grip and is feeling the strain.

Compared to the other fundamental forces in the Universe, gravity is fairly weak. Despite this, gravity has an influence over huge distances and is the driving force behind the motions of the most massive objects in the cosmos. The scattered and warped appearance of the galaxy in this image, NGC 4490, is a prime example of the results of gravity’s unrelenting tug.

Over millions of years, the mutual gravitational attraction between NGC 4490 and its smaller neighbour, NGC 4485, has dragged the two galaxies closer. Eventually, they collided in a swirling crush of stars, gas, and dust. In this image, this most intense period is already over and the two galaxies have moved through each other, untangled themselves, and are speeding apart again. But gravity’s pull is relentless; the galaxies are likely to collide again within a few billion years.

Together NGC 4490 and NGC 4485 form the system Arp 269, which is featured in the Atlas of Peculiar Galaxies. They are located 24 million light-years from Earth in the constellation of Canes Venatici (The Hunting Dogs). The extreme tidal forces of their interaction have determined the shapes and properties of the two galaxies. Once a barred spiral galaxy, similar to the Milky Way, NGC 4490’s outlying regions have been stretched out, resulting in its nickname of the Cocoon Galaxy. Virtually no trace of its past spiral structure can be seen from our perspective, although its companion galaxy NGC 4485 — not pictured here — still clings on to its spiral arms.

This cosmic collision has created rippling patches of higher density gas and dust within both galaxies. The conditions there are ripe for star formation; the brilliant pink pockets of light seen here are dense clouds of ionised hydrogen, glowing as they are irradiated with ultraviolet light from nearby young, hot stars. This spectacular burst of new activity has led to NGC 4490’s classification as a starburst galaxy.

Star formation is also evident in the thin thread that connects the two galaxies: a bridge of stars created by the ancient crash, stretching over the 24 000 light-years that currently separate the fated pair. But where there is life, there is also death. Several supernovae have also been spotted in NGC 4490 over the past few decades, including SN 1982F and SN 2008ax.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/news/heic1716/

Planetary Nebula NGC 7009

Planetary Nebula NGC 7009

The spectacular planetary nebula NGC 7009, or the Saturn Nebula, emerges from the darkness like a series of oddly-shaped bubbles, lit up in glorious pinks and blues. This colourful image was captured by the powerful MUSE instrument on ESO’s Very Large Telescope (VLT), as part of a study which mapped the dust inside a planetary nebula for the first time. The map — which reveals a wealth of intricate structures in the dust, including shells, a halo and a curious wave-like feature — will help astronomers understand how planetary nebulae develop their strange shapes and symmetries.

The Saturn Nebula is located approximately 5000 light years away in the constellation of Aquarius (The Water Bearer). Its name derives from its odd shape, which resembles everyone’s favourite ringed planet seen edge-on.

But in fact, planetary nebulae have nothing to do with planets. The Saturn Nebula was originally a low-mass star, which expanded into a red giant at the end of its life and began to shed its outer layers. This material was blown out by strong stellar winds and energised by ultraviolet radiation from the hot stellar core left behind, creating a circumstellar nebula of dust and brightly-coloured hot gas. At the heart of the Saturn Nebula lies the doomed star, visible in this image, which is in the process of becoming a white dwarf.

In order to better understand how planetary nebulae are moulded into such odd shapes, an international team of astronomers led by Jeremy Walsh from ESO used the Multi Unit Spectroscopic Explorer (MUSE) to peer inside the dusty veils of the Saturn Nebula. MUSE is an instrument installed on one of the four Unit Telescopes of the Very Large Telescope at ESO’s Paranal Observatory in Chile. It is so powerful because it doesn’t just create an image, but also gathers information about the spectrum — or range of colours — of the light from the object at each point in the image.

The team used MUSE to produce the first detailed optical maps of the gas and dust distributed throughout a planetary nebula. The resulting image of the Saturn Nebula reveals many intricate structures, including an elliptical inner shell, an outer shell, and a halo. It also shows two previously imaged streams extending from either end of the nebula’s long axis, ending in bright ansae (Latin for “handles”).

Intriguingly, the team also found a wave-like feature in the dust, which is not yet fully understood. Dust is distributed throughout the nebula, but there is a significant drop in the amount of dust at the rim of the inner shell, where it seems that it is being destroyed. There are several potential mechanisms for this destruction. The inner shell is essentially an expanding shock wave, so it may be smashing into the dust grains and obliterating them, or producing an extra heating effect that evaporates the dust.

Mapping the gas and dust structures within planetary nebulae will aid in understanding their role in the lives and deaths of low mass stars, and it will also help astronomers understand how planetary nebulae acquire their strange and complex shapes.

But MUSE’s capabilities extend far beyond planetary nebulae. This sensitive instrument can also study the formation of stars and galaxies in the early Universe, as well as map the dark matter distribution in galaxy clusters in the nearby Universe. MUSE has also created the first 3D map of the Pillars of Creation in the Eagle Nebula and imaged a spectacular cosmic crash in a nearby galaxy.

Image Credit: ESO/J. Walsh
Explanation from: https://www.eso.org/public/news/eso1731/