Here are a few spectacular images of Galaxies and Nebulae taken by the Hubble Telescope in 2017. Launched in 1990, Hubble continues to provide great contributions to science and images that fill us with peace, joy and inspiration all year long.
Earlier this year, we wrote a similar diary of images from 2016. The images in this diary were released in 2017.
Colliding Galaxies NGC 1512 and NGC 1510
The tiny NGC 1510 and its colossal neighbour NGC 1512 are at the beginning of a lengthy merger, a crucial process in galaxy evolution. Despite its diminutive size, NGC 1510 has had a significant effect on NGC 1512’s structure and amount of star formation.
Galaxies come in a range of shapes and sizes. NGC 1512, the large galaxy to the left in this image, is classified as a barred spiral, named after the bar composed of stars, gas and dust slicing through its centre. The tiny NGC 1510 to the right, on the other hand, is a dwarf galaxy. Despite their very different sizes, each galaxy affects the other through gravity, causing slow changes in their appearances.
Galaxy NGC 6753
Galaxy NGC 6753 is a whirl of color — 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.
At 150 million light-years from Earth, in the constellation of Pavo, NGC 6753 is one of only two known spiral galaxies that were both massive enough and close enough to permit detailed observations of their coronas. Galactic coronas are huge, invisible regions of hot gas that surround a galaxy’s visible bulk, forming a spheroidal shape. Coronas 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.
Galaxy NGC 5559
NGC 5559 is a spiral galaxy, with spiral arms filled with gas and dust sweeping out around the bright galactic bulge. These arms are a rich environment for star formation, dotted with a festive array of colours including the newborn stars glowing blue as a result of their immensely high temperatures.
NGC 5559 lies approximately 240 million light-years away in the northern constellation of Boötes (the herdsman)
In 2001, a calcium-rich supernova called 2001co was observed in NGC 5559. Calcium-rich supernovae (Ca-rich SNe) are described as “fast-and-faint”, as they're less luminous than other types of supernovae and also evolve more rapidly, to reveal spectra dominated by strong calcium lines.
Galaxy UGC 12591
Classified as an S0/Sa galaxy, UGC 12591 sits somewhere between a lenticular and a spiral. It lies just under 400 million light-years away from us in the westernmost region of the Pisces–Perseus Supercluster, a long chain of galaxy clusters that stretches out for 250 million light-years — one of the largest known structures in the cosmos.
The galaxy itself is also extraordinary: it is incredibly massive. The is second-most massive spiral galaxies known to date. The galaxy and its halo together contain several hundred billion times the mass of the Sun; four times the mass of the Milky Way. It also whirls round extremely quickly, rotating at speeds of up to 1.8 million km per hour.
Dwarf galaxy NGC 4625
Dwarf galaxy NGC 4625, is located about 30 million light-years away in the constellation of Canes Venatici (The Hunting Dogs). The image reveals the single spiral arm of the galaxy, which gives it an asymmetric appearance. But why is there only one spiral arm, when spiral galaxies normally have at least two?
Astronomers looked at NGC 4625 in different wavelengths in the hope of solving this cosmic mystery. Observations in the ultraviolet revealed that there are a large number of very young and hot stars forming in the outer regions of the galaxy. This high star formation rate is being triggered by the interaction with a nearby dwarf galaxy called NGC 4618, which has caused NGC 4625 to lose all but one spiral arm.
Galaxy NGC 2623
Galaxy NGC 2623 is located about 250 million light-years away in the constellation of Cancer (The Crab).
NGC 2623 gained its unusual and distinctive shape as the result of a major collision and subsequent merger between two separate galaxies. This violent encounter caused clouds of gas within the two galaxies to become compressed and stirred up, in turn triggering a sharp spike of star formation. This active star formation is marked by speckled patches of bright blue; these can be seen clustered both in the centre and along the trails of dust and gas forming NGC 2623’s sweeping curves (known as tidal tails). These tails extend for roughly 50 000 light-years from end to end. Many young, hot, newborn stars form in bright stellar clusters — at least 170 such clusters are known to exist within NGC 2623.
NGC 2623 is in a late stage of merging. It is thought that the Milky Way will eventually resemble NGC 2623 when it collides with our neighboring galaxy, the Andromeda Galaxy, in four billion years time. See video at the bottom of this diary for an animation of the future merger of our galaxy with Andromeda.
Galaxy NGC 5256
NGC 5256, also known as Markarian 266, is about 350 million light-years away from Earth, in the constellation of Ursa Major (The Great Bear). It is composed of two colliding disc galaxies whose nuclei are currently just 13 000 light-years apart. Their constituent gas, dust, and stars are swirling together in a vigorous cosmic blender, igniting newborn stars in bright star formation regions across the galaxy.
Galaxy NGC 4490
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.
The brilliant pink in the image are regions of intense star formation. Once a barred spiral galaxy, the outlying regions of NGC 4490 have been stretched out, resulting in its nickname of the Cocoon Galaxy.
The two galaxies are located 24 million light-years from Earth in the constellation of Canes Venatici (The Hunting Dogs).
NGC 4302 and NGC 4298
Galaxies NGC 4302 (seen edge-on) and NGC 4298, are located 55 million light-years away in the northern constellation of Coma Berenices (Berenice’s Hair). The pair, discovered by astronomer William Herschel in 1784, form part of the Virgo Cluster, a gravitationally bound collection of nearly 2000 individual galaxies.
The edge-on NGC 4302 is a bit smaller than our own Milky Way Galaxy. The tilted NGC 4298 is even smaller: only half the size of its companion.
Given that they are separated by only around 7000 light-years, astronomers are intrigued by the galaxies’ apparent lack of any significant gravitational interaction; only a faint bridge of neutral hydrogen gas — not visible in this image — appears to stretch between them. The long tidal tails and deformations in their structure that are typical of galaxies lying so close to each other are missing completely.
The Crab Nebula
The Crab Nebula, the result of a bright supernova explosion seen by Chinese and other astronomers in the year 1054, is 6,500 light-years from Earth. At its center is a super-dense neutron star, rotating once every 33 milliseconds, shooting out rotating beams of radio waves and light — a pulsar (the bright dot at image center). The nebula's intricate shape is caused by a complex interplay of the pulsar, a fast-moving wind of particles coming from the pulsar, and material originally ejected by the supernova explosion and by the star itself before the explosion.
This image combines data at different wavelengths from five different telescopes: the VLA (radio) in red; Spitzer Space Telescope (infrared) in yellow; Hubble Space Telescope (visible) in green; XMM-Newton (ultraviolet) in blue; and Chandra X-ray Observatory (X-ray) in purple.
Starburst galaxy Messier 82
Light from a supernova explosion in the nearby starburst galaxy Messier 82 is reverberating off a huge dust cloud in interstellar space. The supernova, called SN 2014J, occurred at the upper right of Messier 82, and is marked by an “X.” The supernova was discovered on 21 January 2014.
The inset images at the top reveal an expanding shell of light from the stellar explosion sweeping through interstellar space, called a “light echo.” The images were taken 10 months to nearly two years after the violent event (6 November 2014 to 12 October 2016). The light is bouncing off a giant dust cloud that extends 300 to 1600 light-years from the supernova and is being reflected toward Earth.
Located about 11 million light-years away, Messier 82 appears high in the constellation Ursa Major, the Great Bear. It is also called the “Cigar Galaxy” because of the elliptical shape produced by the oblique tilt of its starry disk relative to our line of sight.
Kleinmann-Low Nebula
The Kleinmann-Low Nebula, in the heart of the Orion Nebula, is an active star forming region. It is a cluster of stars within a molecular cloud.
This composite image of the Kleinmann-Low Nebula, part of the Orion Nebula complex, is composed of several observations in optical and near-infrared light. Infrared light allows to peer through the dust of the nebula and to see the stars therein. The revealed stars are shown with a bright red colour in the image.
Hubble’s Biggest Discoveries
Galaxy
A galaxy is a gravitationally bound system of stars, planets, gas, dust and dark matter.
Galaxies range in size from dwarfs with just a few billion (109) stars to giants with one hundred trillion (1014) stars. Many galaxies are thought to harbor black holes at their active centers.
Recent estimates of the number of galaxies in the observable universe range from 200 billion (2×1011) to 2 trillion (2×1012) or more.
Our home galaxy, the Milky Way is estimated to contain 100–400 billion stars and 100 billion planets.
Galaxies can interact with each other, collide, pass through each other, pass by each other in near misses and merge.
The Milky Way galaxy is currently in the process of cannibalizing the smaller Sagittarius Dwarf Elliptical Galaxy and the Canis Major Dwarf Galaxy.
Nebula
A Nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases not stars. Some nebulae form from gas that is already in the interstellar medium while others are produced by stars. A nebula is much smaller than a galaxy in size and many are part of larger galaxies.
The Hubble Space Telescope
The Hubble Space Telescope (HST) was launched in 1990 and is still going strong. With a 2.4-meter mirror, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared spectra. After launch by Space Shuttle Discovery in 1990 into an orbit 540 km above the surface of the Earth, five subsequent Space Shuttle missions repaired, upgraded, and replaced systems on the telescope, including all five of the main instruments.
The James Webb Space Telescope, a more powerful space telescope with a 6.5 m primary mirror, operating in the Infrared spectrum, is being readied for launch in October 2018. For more details, please see the diary at www.dailykos.com/….
Our Own Future
The animation below depicts the collision between our Milky Way galaxy and the nearby Andromeda galaxy. Hubble observations indicate that the two galaxies, pulled together by their mutual gravity, will crash together in about 4 billion years and merge over the next few billion years to form a single galaxy. The galaxy product of the collision has been nicknamed Milkomeda or Milkdromeda.
Scientists predict a 12% chance that the Solar System will be ejected from the new galaxy. Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.
However, our Sun itself is going to expand and get much brighter in the next few billion years. In approximately 5 billion years, it will turn into a red giant and will grow so large that it will engulf Mercury, Venus, and probably Earth. Earth will become uninhabitable long before the galactic collision. So, we better “evolve" and find ourselves a new home before these cosmic events occur ;)
References
- Hubble Telescope — hubblesite.org
- Hubble Wiki — en.wikipedia.org/...
- Hubble Twitter — twitter.com/...
- Galaxy and Nebulae photo gallery — hubblesite.org/… hubblesite.org/… eso.org/...
- Galaxies and Nebulae by Hubble (2016) — www.dailykos.com/…
- James Webb Space Telescope diary — www.dailykos.com/...
- Other diaries on Space and Science at — www.dailykos.com/…
P.S. The descriptions of the images are primarily from the Hubble web site; some have been edited for brevity and clarity.