I think everyone knows by now that the amazing images NASA shows from the Hubble Telescope are actually composites made from dozens, sometimes hundreds of images. In a rare behind-the-scenes, NASA has released a timelapse of someone doing the work in the greatest of all image editors, Photoshop.
Hubble images are made, not born. Images must be woven together from the incoming data from the cameras, cleaned up and given colors that bring out features that eyes would otherwise miss. In this video from HubbleSite.org, online home of the Hubble Space Telescope, a Hubble-imaged galaxy comes together on the screen at super-fast speed.
The galaxy NGC 2841 – shown here in this NASA/ESA Hubble Space Telescope image, taken with the space observatory’s newest instrument, the Wide Field Camera 3 – currently has a relatively low star formation rate compared to other spirals. It is one of several nearby galaxies that have been specifically chosen for a new study in which a pick ’n’ mix of different stellar nursery environments and birth rates are being observed.
Star formation is one of the most important processes in shaping the Universe; it plays a pivotal role in the evolution of galaxies and it is also in the earliest stages of star formation that planetary systems first appear.
Yet there is still much that astronomers don’t understand, such as how do the properties of stellar nurseries vary according to the composition and density of the gas present, and what triggers star formation in the first place? The driving force behind star formation is particularly unclear for a type of galaxy called a flocculent spiral, such as NGC 2841 shown here, which features short spiral arms rather than prominent and well-defined galactic limbs.
In an attempt to answer some of these questions, an international team of astronomers is using the new Wide Field Camera 3 (WFC3) installed on the NASA/ESA Hubble Space Telescope to study a sample of nearby, but wildly differing, locations where stars are forming. The observational targets include both star clusters and galaxies, and star formation rates range from the baby-booming starburst galaxy Messier 82 to the much more sedate star producer NGC 2841.
WFC3 was installed on Hubble in May 2009 during Servicing Mission 4, and replaces the Wide Field and Planetary Camera 2. It is particularly well-suited to this new study, as the camera is optimised to observe the ultraviolet radiation emitted by newborn stars (shown by the bright blue clumps in this image of NGC 2841) and infrared wavelengths, so that it can peer behind the veil of dust that would otherwise hide them from view.
While the image shows lots of hot, young stars in the disc of NGC 2841, there are just a few sites of current star formation where hydrogen gas is collapsing into new stars. It is likely that these fiery youngsters destroyed the star-forming regions in which they were formed. Notes
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Image credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration Acknowledgment: M. Crockett and S. Kaviraj (Oxford University, UK), R. O’Connell (University of Virginia), B. Whitmore (STScI) and the WFC3 Scientific Oversight Committee.
Astronomers have pushed the NASA/ESA Hubble Space Telescope to its limits by finding what is plausibly the most distant and ancient object in the Universe ever seen. Its light has travelled for 13.2 billion years to reach Hubble, which corresponds to a redshift around 10. The age of the Universe is 13.7 billion years.
The dim object, called UDFj-39546284, is likely to be a compact galaxy of blue stars that existed 480 million years after the Big Bang, only four percent of the Universe’s current age. It is tiny. Over one hundred such mini-galaxies would be needed to make up our own galaxy, the Milky Way.
This galaxy would be more distant than the population of redshift 8 galaxies recently discovered in the Hubble Ultra Deep Field, including the current most distant spectroscopically confirmed record holder at a redshift of 8.6 (eso1041), and the redshift 8.2 gamma-ray burst from 2009 (eso0917). A redshift of z = 8.6 means that the object is seen as it was around 600 million years after the Big Bang.
“We’re seeing huge changes in the rate of star birth that tell us that if we go a little further back in time we’re going to see even more dramatic changes,” says Garth Illingworth of the University of California at Santa Cruz.
The astronomers were surprised, as this new result suggests that the rate at which galaxies were forming stars grew precipitously, increasing by a factor of ten over the 170 million years that elapsed between the era of this newly discovered candidate galaxy and that of the population of previously identified galaxies at a redshift around 8 (650 million years after the Big Bang).
“These observations provide us with our best insights yet into the likely nature of the earlier generation of primeval objects that we are yet to find,” adds Rychard Bouwens of Leiden University in the Netherlands.
Astronomers don’t know exactly when the first stars appeared in the Universe, but every step further from Earth takes them deeper into the early Universe’s formative years when stars and galaxies were just beginning to emerge in the aftermath of the Big Bang.
“We’re moving into a regime where there are big changes afoot. Another couple of hundred million years back towards the Big Bang, and that will be the time when the first galaxies really are starting to build up,” says Illingworth.
Bouwens and Illingworth are reporting the discovery in the 27 January issue of the British science journal Nature.
The even more distant proto-galaxies that the team expects are out there will require the infrared vision of the NASA/ESA/CSA James Webb Space Telescope (JWST), which is the successor to Hubble. Planned for launch later this decade, JWST will provide the spectroscopic measurements that will confirm today’s report of the object’s tremendous distance.
A year of detailed analysis was required before the object was identified in the Hubble Ultra Deep Field — Infrared (HUDF-IR) data taken in the late summers of 2009 and 2010. The object appears as a faint dot of starlight in the Hubble exposures, and although its individual stars can’t be resolved by Hubble, the evidence suggests that this is a compact galaxy of hot stars that first started to form over 100-200 million years earlier, from gas trapped in a pocket of dark matter.
The proto-galaxy is only visible at the longest infrared wavelengths observable by Hubble. This means that the expansion of the Universe has stretched and thereby reddened its light more than that of any other galaxy previously identified in the HUDF-IR, taking it to the very limit that Hubble can detect. JWST will go deeper into infrared wavelengths and will be at least an order of magnitude more sensitive than Hubble, allowing it to hunt more efficiently for primeval galaxies at even greater distances, at earlier times, closer to the Big Bang. Notes
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Image credit: NASA, ESA, G. Illingworth (University of California, Santa Cruz), R. Bouwens (University of California, Santa Cruz, and Leiden University) and the HUDF09 Team
In 2007, Dutch school teacher Hanny van Arkel participated in the Galaxy Zoo project. She discover this strange green blob on an image, and it was named Hanny’s Voorwerp. Hanny’s Voorwerp is Dutch for Hanny’s object. It lies approximately 700 million light-years away from Earth near the spiral galaxy IC 2497 in the constellation Leo Minor.
The strange green blob floating near the spiral galaxy begs the question: “What is it?” It turns out that IC 2497 is what astronomers call an active galactic nucleus or quasar. The quasar is powered by a massive black hole at the center of the galaxy. Right now, the quasar is no longer active. In other words, it is now turned off, which makes it a transient phenomena. The radiation from the AGN has illuminated a gas cloud trailing behind the galaxy, and is triggering the formation of new stars. This illuminated section of the gas cloud is Hanny’s Voorwerp. What we are seeing in Hanny’s Voorwerp is a light echo. It is an echo of the radiation that came from the now inactive quasar.
An active galactic nucleus (AGN) is the center of a galaxy that has a supermassive black hole being fed by gas and dust near it. At one time, such AGN’s were called quasars, which is short for quasi-stellar radio source. Also at one time, our own Milky Way galaxy may have had an AGN, until its central black hole consumed all the gas and dust near it.
However, an alternative theory is that an AGN comes from the merger of two galaxies. So which theory is correct? That is what the Hubble Space Telescope set out to prove.
Most galaxies, including our own, have a huge but well-behaved black hole at their heart, while some have messy eaters that suck in vast amounts of matter which then shines brightly as it falls towards oblivion. This causes the telltale bright spots at the centre of galaxies known as active galactic nuclei (AGN). Why are the two types so different? Until now, the leading theory has been that mergers between galaxies are instrumental in driving matter into the black holes, making them grow.
In a new study, the largest of its kind so far, astronomers set up an identity parade of galaxies to test this theory. Comparing 140 active galaxies with a control group of over 1200 comparable inactive galaxies, they found that there has been no significant link between AGN activity and galactic mergers for at least the past eight billion years. Therefore, other phenomena such as instabilities within galaxies, collisions of molecular clouds or tidal disruption by other galaxies flying by must instead be to blame.
Hubble has recently imaged an expanding shock wave from a supernova that exploded 400 years ago. This supernova, called SNR B0509-67.5, is located approximately 160,000 light years from earth. When it exploded, the supernova would have been visible from the southern hemisphere. SNR B0509-67.5 has been imaged by the Chandra X-ray observatory as well.
Hubble has spotted a festive bauble of gas in our neighbouring galaxy, the Large Magellanic Cloud. Formed in the aftermath of a supernova explosion that took place four centuries ago, this sphere of gas has been snapped in a series of observations made between 2006 and 2010.
The delicate shell, photographed by the NASA/ESA Hubble Space Telescope, appears to float serenely in the depths of space, but this apparent calm hides an inner turmoil. The gaseous envelope formed as the expanding blast wave and ejected material from a supernova tore through the nearby interstellar medium. Called SNR B0509-67.5 (or SNR 0509 for short), the bubble is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud (LMC), a small galaxy about 160 000 light-years from Earth.
Ripples seen in the shell’s surface may be caused either by subtle variations in the density of the ambient interstellar gas, or possibly be driven from the interior by fragments from the initial explosion. The bubble-shaped shroud of gas is 23 light-years across and is expanding at more than 18 million km/h.
Astronomers have concluded that the explosion was an example of an especially energetic and bright variety of supernova. Known as Type Ia, such supernova events are thought to result when a white dwarf star in a binary system robs its partner of material, taking on more mass than it is able to handle, so that it eventually explodes.
Hubble’s Advanced Camera for Surveys observed the supernova remnant on 28 October 2006 with a filter that isolates light from the glowing hydrogen seen in the expanding shell. These observations were then combined with visible-light images of the surrounding star field that were imaged with Hubble’s Wide Field Camera 3 on 4 November 2010.
With an age of about 400 years, the supernova might have been visible to southern hemisphere observers around the year 1600, although there are no known records of a “new star” in the direction of the LMC near that time. A much more recent supernova in the LMC, SN 1987A, did catch the eye of Earth viewers and continues to be studied with ground- and space-based telescopes, including Hubble. Notes
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA). Acknowledgement: J. Hughes (Rutgers University)
Yesterday we showed you a video showing the globular cluster Omega Centauri, and answering the question as to whether or not a black hole was at its center. Today we look at what happens if you took that same data, and plotted it as a scatter graph of stars. On the X-axis of the scatter graph we have a stars temperature . On the Y-axis of the scatter graph we have a stars intrinsic brightness. This is called a Hertzsprung-Russell diagram. When applied to the globular cluster Omega Centauri, you can see some interesting things.
In this video, the stars in globular cluster Omega Centauri are rearranged according to their intrinsic brightness (vertical axis) and their temperature (horizontal axis). The temperature of a star dictates its apparent colour, with cooler stars being red and hotter ones being blue. The majority of stars at any given time fall into a wide band known as the main sequence, which passes from the top left (hot, bright stars) to the bottom right (cool, dim stars). However this is just a snapshot in time — as stars evolve they do not stay fixed to one point on the diagram for the whole of their lives.
Credit:
NASA, ESA, J. Anderson and R. van der Marel (STScI)
A globular cluster is a spherical collection of stars tightly bound by gravity. The globular cluster Omega Centauri is located approximately 15,800 light-years from Earth. This globular cluster contains several million stars. Some scientist think that a black hold lies at the center of Omega Centauri. Using the Hubble Space Telescope, astronomers measured the motions of more than 100,000 of its stars. From this they can predict the motions of the stars some 10,000 years into the future. Does a black hole lie at the center of the Omega Centauri globular cluster? Based on this, astronomers do not think so.
Though the universe is chock full of spiral-shaped galaxies, no two look exactly the same. This face-on spiral galaxy, called NGC 3982, is striking for its rich tapestry of star birth, along with its winding arms. The arms are lined with pink star-forming regions of glowing hydrogen, newborn blue star clusters, and obscuring dust lanes that provide the raw material for future generations of stars. The bright nucleus is home to an older population of stars, which grow ever more densely packed toward the center.
NGC 3982 is located about 68 million light-years away in the constellation Ursa Major. The galaxy spans about 30,000 light-years, one-third of the size of our Milky Way galaxy. This color image is composed of exposures taken by the Hubble Space Telescope’s Wide Field Planetary Camera 2 (WFPC2), the Advanced Camera for Surveys (ACS), and the Wide Field Camera 3 (WFC3). The observations were taken between March 2000 and August 2009. The rich color range comes from the fact that the galaxy was photographed invisible and near-infrared light. Also used was a filter that isolates hydrogen emission that emanates from bright star-forming regions dotting the spiral arms.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, D.C.
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) Acknowledgment: A. Riess (STScI)
NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.
This video, based on a series of observations made by Hubble’s Wide Field Camera 3, clearly shows the slow evolution of the debris coming from asteroid P/2010 A2. When astronomers first spotted the unusual X shape, they assumed that they were observing the immediate aftermath of an impact. However, the slower than anticipated rate of change in the appearance of the debris suggests that the collision in fact took place a year earlier.
I think everyone knows by now that the amazing images NASA shows from the Hubble Telescope are actually composites made from dozens, sometimes hundreds of images. In a rare behind-the-scenes, NASA has released a timelapse of someone doing the work in the greatest of all image editors, Photoshop.
VizWorld.com 
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