The picture shows Abell 2218, a rich galaxy cluster composed of thousands of individual galaxies. It sits about 2.1 billion light-years from the Earth (redshift 0.17) in the northern constellation of Draco. When used by astronomers as a powerful gravitational lens to magnify distant galaxies, the cluster allows them to peer far into the Universe. However, it not only magnifies the images of hidden galaxies, but also distorts them into long, thin arcs.
Several arcs in the image can be studied in detail thanks to Hubble's sharp vision. Multiple distorted images of the same galaxies can be identified by comparing the shape of the galaxies and their colour. In addition to the giant arcs, many smaller arclets have been identified.
NASA, ESA, and Johan Richard (Caltech, USA)
Acknowledgement: Davide de Martin & James Long (ESA/Hubble)
By Elizabeth Howell, Space.com Contributor / March 29, 2018
Night sky photographer Amit Ashok Kamble captured this amazing paannama of the Milky Way over Pakiri Beach, New Zealand by stitching 10 images together into a complete mosaic. Image submitted May 5, 2014. Credit: Amit Ashok Kamble
The Milky Way is the galaxy in which the Earth resides. Part of it is visible on a clear night from Earth, as a thick band of stars stretching across the sky. We can see thousands of these stars with the naked eye, and many more in a telescope. But how many stars are in the Milky Way?
"It's a surprisingly difficult question to answer. You can't just sit around and count stars, generally, in a galaxy," said David Kornreich, an assistant professor at Ithaca College in New York. He was the founder of the "Ask An Astronomer" service at Cornell University.
Even in the Andromeda Galaxy — which is bright, large and relatively close by Earth, at 2.3 million light-years away — only the largest stars and a few variable stars (notably Cepheid variables) are bright enough to shine in telescopes from that distance. A sun-size star would be too difficult for us to see. So astronomers estimate, using some of the techniques below.
The Milky Way's structure
From observations, astronomers know that the Milky Way is a barred spiral galaxy that is about 100,000 light-years across. A view outside the galaxy would reveal a central bulge surrounded by four arms, two major and two minor. The Milky Way's major arms are known as Perseus and Sagittarius. The sun is located in one of two minor spurs, which is called the Orion Arm.
The galaxy also has a huge hot-gas halo around it that is several hundreds of thousands of light-years in diameter. Astronomers estimate that the halo is just as massive as all of the stars in the Milky Way. Many of the Milky Way's stars, however, are tough to view. That is because the center of the galaxy has a galactic bulge filled with stars, gas and dust — as well as a supermassive black hole. This area is so thick with material that even powerful telescopes cannot see through it. Astronomers aren't sure when and how the bulge formed; some suggest that the Milky Way's early history was changed when the galaxy collided with another one.
Astronomers used to think that all of the stars in the universe were located inside of the Milky Way, but that changed in the 1920s. Astronomer Edwin Hubble used a star called a Cepheid variable to measure distances in the sky. From there, astronomers learned that there were whole galaxies in the universe separate from the Milky Way. Massive investigation
The primary way astronomers estimate stars in a galaxy is by determining the galaxy's mass. The mass is estimated by looking at how the galaxy rotates, as well as its spectrum using spectroscopy.
All galaxies are moving away from each other, and their light is shifted to the red end of the spectrum because this stretches out the light's wavelengths. This is called "redshift." In a rotating galaxy, however, there will be a portion that is more "blueshifted" because that portion is slightly moving toward Earth. Astronomers must also know what the inclination or orientation of the galaxy is before making an estimate, which is sometimes simply an "educated guess," Kornreich said.
A technique called "long-slit spectroscopy" is best for performing this type of work. Here, an elongated object such as a galaxy is viewed through an elongated slit, and the light is refracted using a device such as a prism. This breaks out the colors of the stars into the colors of the rainbow.
Some of those colors will be missing, displaying the same "patterns" of missing portions as certain elements of the periodic table. This lets astronomers figure out what elements are in the stars. Each type of star has a unique chemical fingerprint that would show up in telescopes. (This is the basis of the OBAFGKM sequence astronomers use to distinguish between types of stars.)
Any kind of telescope can do this sort of spectroscopy work. Kornreich often uses the 200-inch telescope at the Palomar Observatory at the California Institute of Technology, but he added that almost any telescope of sufficient size would be adequate.
The ideal would be using a telescope in orbit because scattering occurs in Earth's atmosphere from light pollution and also from natural events — even something as simple as a sunset. The Hubble Space Telescope is one observatory known for this sort of work, Kornreich added. A successor observatory called the James Webb Space Telescope is expected to launch in 2020. The challenge, however, is that Hubble is a telescope in high demand – and the same is expected of Webb after its launch. So the observatories can't spend all of their time estimating galaxy mass.
How much of the mass is stars?
Between different galaxies of the same mass, there could be variances as to the types of stars and the overall mass. Kornreich cautioned this would be very hard to speak about generally, but said that one difference could be looking at elliptical galaxies vs. spiral galaxies such as our own, the Milky Way. Elliptical galaxies tend to have more K- and M-type red dwarf stars than spiral galaxies. Because elliptical galaxies are older, they will have less gas because that was blown away during their evolution.
Once a galaxy's mass is determined, the other tricky thing is figuring out how much of that mass is made of stars. Most of the mass will be made up of dark matter, a type of matter that emits no light but which is believed to make up most of the mass of the universe.
"You have to model the galaxy and see if you can understand what the percentage of that mass of stars is," Kornreich said. "In a typical galaxy, if you measure its mass by looking at the rotation curve, about 90 percent of that is dark matter."
With much of the remaining "stuff" in the galaxy made up of diffuse gas and dust, Kornreich estimated that about 3 percent of the galaxy's mass will be made up of stars, but that could vary. Further, the size of the stars itself can greatly vary from something that is the size of our sun, to something dozens of times smaller or bigger.The number of stars is approximately …
So is there any way to figure out how many stars are for sure? In the end, it comes down to an estimate. In one calculation, the Milky Way has a mass of about 100 billion solar masses, so it is easiest to translate that to 100 billion stars. This accounts for the stars that would be bigger or smaller than our sun, and averages them out. However, the mass is tough to calculate — other estimates have said the galaxy has a mass of between 400 billion and 700 billion solar masses.
The European Space Agency's Gaia mission is mapping the locations of approximately 1 billion stars in the Milky Way. ESA says Gaia will map 1 percent of the stellar content in the Milky Way, which puts the estimate of the total stars in our galaxy at 100 billion. Gaia's goal is to make the best-ever three-dimensional map of the Milky Way.
The caveat, Kornreich said, is that these numbers are approximations. More advanced models can make the approximation more accurate, but it would be very difficult to count the stars one by one and tell you for sure how many are in the galaxy.
This image is packed full of galaxies! A keen eye can spot exquisite ellipticals and spectacular spirals, seen at various orientations: edge-on with the plane of the galaxy visible, face-on to show off magnificent spiral arms, and everything in between. The vast majority of these specks are galaxies, but to spot a foreground star from our own galaxy, you can look for a point of light with tell-tale diffraction spikes. The most alluring subject sits at the centre of the frame. With the charming name of SDSSJ0146-0929, the glowing central bulge is a galaxy cluster — a monstrous collection of hundreds of galaxies all shackled together in the unyielding grip of gravity. The mass of this galaxy cluster is large enough to severely distort the spacetime around it, creating the odd, looping curves that almost encircle the cluster. These graceful arcs are examples of a cosmic phenomenon known as an Einstein ring. The ring is created as the light from a distant objects, like galaxies, pass by an extremely large mass, like this galaxy cluster. In this image, the light from a background galaxy is diverted and distorted around the massive intervening cluster and forced to travel along many different light paths towards Earth, making it seem as though the galaxy is in several places at once.
Credit: ESA/Hubble & NASA Acknowledgement: Judy Schmidt
More than halfway across the universe, an enormous blue star nicknamed Icarus is the farthest individual star ever seen. Normally, it would be much too faint to view, even with the world’s largest telescopes. But through a quirk of nature that tremendously amplifies the star’s feeble glow, astronomers using NASA’s Hubble Space Telescope were able to pinpoint this faraway star and set a new distance record. They also used Icarus to test one theory of dark matter, and to probe the make-up of a foreground galaxy cluster.
The star, harbored in a very distant spiral galaxy, is so far away that its light has taken 9 billion years to reach Earth. It appears to us as it did when the universe was about 30 percent of its current age.
Icarus, whose official name is MACS J1149+2223 Lensed Star 1, is the farthest individual star ever seen. It is only visible because it is being magnified by the gravity of a massive galaxy cluster, located about 5 billion light-years from Earth. Called MACS J1149+2223, this cluster, shown at left, sits between Earth and the galaxy that contains the distant star. The panels at the right show the view in 2011, without Icarus visible, compared with the star's brightening in 2016. Credits: NASA, ESA, and P. Kelly (University of Minnesota)
The discovery of Icarus through gravitational lensing has initiated a new way for astronomers to study individual stars in distant galaxies. These observations provide a rare, detailed look at how stars evolve, especially the most luminous stars.
“This is the first time we’re seeing a magnified, individual star,” explained former University of California at Berkeley postdoc and study leader Patrick Kelly now of the University of Minnesota, Twin Cities. “You can see individual galaxies out there, but this star is at least 100 times farther away than the next individual star we can study, except for supernova explosions.”
The search for dark matter is one of the strangest enduring scientific mysteries. Astronomers and astrophysicists believe that up to 95% of the universe could be composed of so-called dark matter and energy, “dark” meaning these forms of matter do not reflect light, x-rays, or any other radiation like all other the other stuff in the known universe does. Thus, the presence of dark matter and energy is often inferred from the gravitational effects they have on other objects and forms of energy. Dark matter is thought to be distributed throughout the entire universe, but a new discovery made by Yale astronomers might turn that thinking on its head. If we can only detect a small fraction of the 'stuff' out there in the cosmos, who knows what mysteries and wonders lie just beyond the scope of our sense?
If we can only detect a small fraction of the ‘stuff’ out there in the cosmos, who knows what mysteries and wonders lie just beyond the scope of our sense?
A team of astronomers mostly from Yale University have detected the first known galaxy which is completely devoid of dark matter, revealing a cosmic mystery which has left them at a loss to explain it. A study of this “ghostly” galaxy has been published in Nature. According to the astronomers’ findings thus far, the presence of this unique galaxy may challenge the current thinking about dark matter and its distribution throughout the cosmos:
NGC1052–DF2 enables us to make the complementary point that dark matter does not always coincide with galaxies: it is a distinct ‘substance’ that may or may not be present in a galaxy. Furthermore, and paradoxically, the existence of NGC1052–DF2 may falsify alternatives to dark matter
The galaxy was detected using the world’s largest telescopes at the W. M. Keck Observatory in Hawaii, as well as the Hubble Space Telescope. Pieter van Dokkum, lead author of the study, says this galaxy, named, NGC1052-DF2 leaves a “ghostly glow in the sky” due to its lack of dark matter.
The Keck telescopes in Hawaii.
It’s currently unknown how the galaxy formed, although a few theories suggest clouds of cosmic gases could have been blown out of other galaxies. Naturally, though, astronomers are cautioning drawing any conclusions since this is such a rare and unique case and there is still little data on the anomalous galaxy. Still, the ‘ghostly’ NGC1052-DF2 reveals ours is truly a mysterious universe.
This NASA/ESA Hubble Space Telescope image shows a massive galaxy cluster glowing brightly in the darkness. Despite its beauty, this cluster bears the distinctly unpoetic name of PLCK_G308.3-20.2.
Galaxy clusters can contain thousands of galaxies all held together by the glue of gravity. At one point in time they were believed to be the largest structures in the Universe — until they were usurped in the 1980s by the discovery of superclusters, which typically contain dozens of galaxy clusters and groups and span hundreds of millions of light-years. However, clusters do have one thing to cling on to; superclusters are not held together by gravity, so galaxy clusters still retain the title of the biggest structures in the Universe bound by gravity.
One of the most interesting features of galaxy clusters is the stuff that permeates the space between the constituent galaxies: the intracluster medium (ICM). High temperatures are created in these spaces by smaller structures forming within the cluster. This results in the ICM being made up of plasma — ordinary matter in a superheated state. Most luminous matter in the cluster resides in the ICM, which is very luminous X-rays. However, the majority of the mass in a galaxy cluster exists in the form of non-luminous dark matter. Unlike plasma, dark matter is not made from ordinary matter such as protons, neutrons and electrons. It is a hypothesised substance thought to make up 80 % of the Universe’s mass, yet it has never been directly observed.
This image was taken by Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3 as part of an observing programme called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA/ESA/CSA James Webb Space Telescope (JWST) to study.
"We Truly Don't Know What It Is" --Mystery Milky-Way Spectrum of Light Observed 'Not Produced By Any Known Emission'
The Daily Galaxy via University of Miami
Posted on April 17, 2018
"We use special telescopes to catch X-ray light in the sky, and while looking at these X-rays, the telescopes noticed an unexpected feature and captured a spectrum of light, which is not produced by any known atomic emission," said University of Miami astrophysicist Nico Cappelluti. "This emission line is now called the 3.5 kiloelectron volt (keV). One interpretation of this emission line is that it's produced by the decay of dark matter." "This 3.5 keV emission line is unidentified. We truly don't know what it is," said Esra Bulbul, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics and co-author in Cappelluti's study. "But one theory is that it could be a sterile neutrino, which is also known as decaying dark matter. What is truly interesting about Dr. Cappelluti's study is that he found this 3.5 keV line within our own galaxy."
In 2014, a team of astronomers led by Bulbul discovered a noticeable spike in intensity at a very specific energy level. While studying the hot gas within the Perseus galaxy cluster (image above), the Chandra and XMM-Newton observatories revealed an unexpected spike, or emission line, corresponding to an energy of 3.5 kiloelectron volts (keV). This wavelength is very difficult to explain, as it cannot be described by previously observed – or even predicted – astronomical objects.
"If confirmed, this will tell us what dark matter is and could be one of the major discoveries in physics," said Cappelluti. "We know that the Milky Way is surrounded by dark matter. Think of it as if we are living in a bubble of dark matter. But we also want to have the statistical certainty of our detection, so now we are putting together a Sterile Neutrino Task Force."
Cappelluti is intrigued by the cosmic phenomena of super massive black holes, the nature of dark matter, and active galactic nuclei, which is the very bright light source found at the center of many galaxies.His recent published findings that could give insight on a subject scientists and astrophysicists have been investigating for decades: What is dark matter and where does it come from?
Cappelluti's study, published in The Astrophysical Journal and entitled, "Searching for the 3.5 keV line in the deep fields with Chandra: the 10 MS observations," examines an interesting light source that was captured by four different telescopes each pointing in a different direction in the sky. The source of light is unfamiliar and unrecognizable to scientists and has caused quite a stir in the world of astrophysics. Bulbul also found the emission line while studying clusters of galaxies in 2014.
The atomic emission spectra is shown below for various elements. Each thin band in each spectrum corresponds to a single, unique transition between energy levels in an atom. (Rochester Institute of Technology, CC BY-NC-SA 2.0).
The four telescopes that captured the 3.5 keV emission were NASA's NuSTAR telescope, the European Space Agency's (ESA) XMM-Newton telescope, the Chandra telescope, and the Suzaku telescope from Japan.
This fall, several scientists from around the world, including Harvard's Bulbul, plan to gather at the University of Miami to organize a massive data-mining project to investigate and research this 3.5 keV emission line.
"The goal now is to continue to look at the sky until we obtain more powerful operating telescopes with better resolution, which won't be ready until 2021, and share and analyze data from other scientists who are trying to uncover the secrets of dark matter," said Bulbul.
#HubbleClassic This image of 2 interacting galaxies called Arp194 was released for Hubble's 19th anniversary. A blue-colored "fountain" of material between the galaxies makes them resemble a question mark. What will this year's Hubble anniversary image be? go.nasa.gov/2J1Oor5
And here is more info on the galaxy some of us call home:
Gaia’s 2nd data release: 1.7 billion stars!
By Deborah Byrd in SPACE | April 26, 2018
Why did ESA’s director of science say Gaia’s observations are “redefining the foundations” of astronomy? Also, links to virtual reality resources made possible by Gaia, available for you to explore.
Gaia’s view of our home galaxy, the Milky Way, in a 360 degree interactive view(click arrows in upper left)via ESA/Gaia/DPAC; ATG medialab.
It was less than a century ago, in 1920, that astronomers were famously debating the nature of so-called spiral nebulae. Some believed they lay inside our own Milky Way galaxy and were, perhaps, forming solar systems. Others thought they were large and distant separate galaxies. Thus the wisest astronomers of yesteryear couldn’t be sure of the true nature of our home galaxy, the Milky Way. They couldn’t know it is indeed one galaxy of billions in the universe. And they couldn’t have imagined that now, just 100 years later, we’d have a space observatory like Gaia, whose goal is nothing less than to provide a 3D map of our galaxy. This mission had its second data release this week, along with a host of virtual reality resources for scientists and the public. The European Space Agency (ESA) said Gaia’s data makes possible:
"… the richest star catalog to date, including high-precision measurements of nearly 1.7 billion stars and revealing previously unseen details of our home galaxy."
The new data, which ESA called phenomenal, is based on 22 months of Gaia’s charting of the sky. Günther Hasinger, ESA’s director of science, said:
"The observations collected by Gaia are redefining the foundations of astronomy."
Why all the superlatives? What’s so amazing about Gaia’s data?
Gaia gathers its phenomenal data in the most unglamorous of ways, via what’s called astrometry. Okay, now, hang in there with me. Think about this. Gaia’s job is to scan the sky repeatedly, observing each of its targeted billion stars an average of 70 times over its five-year mission. So, for example, we know our sun and all the stars in the Milky Way are moving continuously in great orderly masses around the center of our galaxy. We know that … but we didn’t have many details about how each star moves. How could we? The data for so many stars would be (are) massive; collecting the data, storing it and analyzing it requires today’s spacecraft and computer technologies.
Over its five years, again and again and again, Gaia will acquire data points on the positions of Milky Way stars. Thus astronomers have already been able to produce an illustration like the very wonderful one below, which shows median velocities (the distances and directions traveled by each star per unit of time) of stars in our Milky Way.
And so we begin to see – not just see in our minds, but actually see via Gaia’s actual data – that, due to the movements of its stars, our Milky Way galaxy is rotating, with us in its midst. You can see that in one illustration of Gaia’s data, below:
All-sky map of median velocities of about a billion stars toward or away from our sun, made possible by the Gaia mission. When you look at this map, you’re seeing a large-scale pattern caused by rotation of our Milky Way galaxy. Image via DPAC/ESA/STFC.
And that’s just one example of the type of insight Gaia’s data can provide. ESA said:
"Gaia was launched in December 2013 and started science operations the following year. The first data release, based on just over one year of observations, was published in 2016; it contained distances and motions of two million stars.
The new data release, which covers the period between July 25, 2014, and May 23, 2016, pins down the positions of nearly 1.7 billion stars, and with a much greater precision. For some of the brightest stars in the survey, the level of precision equates to Earth-bound observers being able to spot a Euro coin lying on the surface of the moon."
Gaia is also gathering other types of data. The illustration below shows some of the ways in which Gaia sees our Milky Way:
Gaia’s all-sky view of our Milky Way galaxy and neighboring galaxies. The maps show the total brightness and color of stars (top), the total density of stars (middle) and the interstellar dust that fills the galaxy (bottom). These images are based on observations performed by the ESA satellite in each portion of the sky between July 2014 and May 2016, which were published as part of the Gaia second data release on April 25, 2018. Image via ESA.
Virtual Reality Resources Also, along with this second data release by Gaia, ESA has released several virtual reality resources to help visualize Gaia’s extraordinary data set, both for public outreach and for scientific purposes.
One of the public offerings is Gaia Sky, a real-time, 3D astronomy visualisation software that runs on Windows, Linux and MacOS, developed in the framework of ESA’s Gaia mission by the Gaia group at the Astronomisches Rechen-Institut (Zentrum für Astronomie Heidelberg, University of Heidelberg, Germany). It contains a simulation of our solar system, a view of the second Gaia data release (with different selections based on parallax relative errors, ranging from a few million to hundreds of millions of stars), and additional astronomical and cosmological data to visualize star clusters, nearby galaxies, distant galaxies and quasars, and the Cosmic Microwave Background. The data are extensive, and you’ll want to explore them yourself here:zah.uni-heidelberg.de/institutes/ari/gaia/outreach/gaiasky/
So you can see … there’s really a lot here to think about and explore, both for the public and for scientists. And maybe you can begin to see that – to those astronomers debating the nature of spiral nebulae in 1920 – Gaia’s data might have seemed nothing short of miraculous!
An artist's impression of 14 galaxies that are in the process of merging. Eventually, they will form the core of a massive galaxy cluster. (NRAO/AUI/NSF; S. Dagnello)
It's a cosmic pileup in the far reaches of the universe and nothing like it has ever been seen before.
Using the most powerful telescopes on Earth, astronomers have spotted 14 burning-hot galaxies hurtling toward each other on an inevitable galactic collision course at the edge of the observable universe.
Computer models show that when these galaxies do collide they will form the core of a colossal galaxy cluster so large it will be the most massive structure known in the cosmos.
This chaotic, energy-filled region, described Wednesday in Nature, is called a protocluster, and researchers say it is more active than any other section of the universe they have ever observed.
"There are huge energetics involved, like 10,000 supernova going off at a time, quite literally," said Scott Chapman, a physicist at Dalhousie University in Halifax, Canada, who worked on the study.
As if all that wasn't crazy enough, the authors said that the 14 galaxies are known as "starburst galaxies," which means they are forming stars at a furious rate.
The research team estimates that they could be making stars as much as 1,000 times faster than the Milky Way.
And they are all crammed into a space just three times the size of our own galaxy.
In addition, the whole system is located 90% of the way to the edge of the observable universe.
It is so far away that it takes light 12.4 billion years to travel across space from the protocluster to telescopes on Earth.
That means that this glowing star-generator formed just 1.4 billion years after the universe itself came into being.
And it's that fact in particular that has astrophysicists scratching their heads.
"We don't know how it is possible," Chapman said. "We don't know how you get those 14 galaxies right down the center of the protocluster at such an early time."
Nothing that big and active should have been able to form so long ago, he said.
"We see the structure of the universe building up slowly from little bits, and then merging together to make bigger bits. We don't expect bigger galaxies to form until much later," he said.
The earliest hint that something strange was going on in this part of the sky came in 2010 from data collected by the South Pole Telescope in Antarctica.
Although this instrument was designed to find relatively nearby galaxy clusters, astronomers realized it could also be used to spot extremely bright structures from a great distance away in both space and time.
The protocluster described in the new work showed up as a small but unusual smudge of light.
Still, astronomers found it compelling enough to request time on the ALMA telescope in the Chilean desert to take a closer look at its structure.
An ALMA image of 14 galaxies forming a protocluster known as SPT2349-56. These galaxies are in the process of merging and will eventually form the core of a truly massive galaxy cluster. (ALMA (ESO/NAOJ/NRAO); B. Saxton (NRAO/AUI/NSF))
Observations made with ALMA revealed that the center of the smudge was actually 14 distinct galaxies and that the protocluster was a whopping 12.4 billion light-years from Earth.
Chapman said that was one of the big "wow" moments.
"If it had been much closer it would still be the busiest place in the universe that we know of, but it would be less shocking," he said.
ALMA is great at zooming in and seeing details of objects, but it has a very narrow field of view, Chapman said. It could only see the center of the smudge that the South Pole Telescope detected.
The authors estimate that there could be 1,000 more galaxies in the surrounding region of space.
"Most of them will be too faint to see, even with ALMA, but we can probably find another 50 galaxies," Chapman said.
The team has already started looking. Chapman said new observations are coming in even now.
"This really launched a massive study," he said.
In the meantime, astronomers will be busy puzzling over how such a large structure could form so early in the universe.
Expect new hypotheses to come soon.
"People are very resourceful at coming up with answers, after the fact," Chapman said.
The NASA/ESA Hubble Space Telescope has produced an incredibly detailed image of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the two are in chance alignment from our vantage point.
Explanation: A small crystal ball seems to hold a whole galaxy in this creative snapshot. Of course, the galaxy is our own Milky Way. Its luminous central bulge marked by rifts of interstellar dust spans thousands of light-years. On this long southern hemisphere night it filled dark Chilean skies over Paranal Observatory. The single exposure image did not require a Very Large Telescope, though. Experiments with a digital camera on a tripod and crystal ball perched on a handrail outside the Paranal Residencia produced the evocative, cosmic marble portrait of our home galaxy.
Image Credit & Copyright: Adam Block, Mt. Lemmon SkyCenter, U. Arizona
Explanation: What kind of celestial object is this? A relatively normal galaxy -- but seen from its edge. Many disk galaxies are actually just as thin as NGC 5866, pictured here, but are not seen edge-on from our vantage point. A perhaps more familiar galaxy seen edge-on is our own Milky Way Galaxy. Cataloged as M102 and NGC 5866, the Spindle galaxy has numerous and complex dust lanes appearing dark and red, while many of the bright stars in the disk give it a more blue underlying hue. The blue disk of young stars can be seen extending past the dust in the extremely thin galactic plane. There is evidence that the Spindle galaxy has cannibalized smaller galaxies over the past billion years or so, including multiple streams of faint stars, dark dust that extends away from the main galactic plane, and a surrounding group of galaxies (not shown). In general, many disk galaxies become thin because the gas that forms them collides with itself as it rotates about the gravitational center. The Spindle galaxy lies about 50 million light years distant toward the constellation of the Dragon (Draco).
Behold, the Milky Way! Our Galaxy Glitters in This Spectacular Photo
By Miguel Claro, Space.com Contributor / September 7, 2018
A paannamic view captured from the village of Campinho in Portugal's Dark Sky Alqueva Reserve shows the arc of the Milky Way as seen during a spring night in the Northern Hemisphere. The scene also includes Mars, Saturn and Jupiter. Credit: Miguel Claro
Miguel Claro is a professional photographer, author and science communicator based in Lisbon, Portugal, who creates spectacular images of the night sky. As a European Southern Observatory photo ambassador, a member of The World At Night and the official astrophotographer of the Dark Sky Alqueva Reserve, he specializes in astronomical skyscapes that connect Earth and the night sky. Join Miguel here as he takes us through his photograph "A Spring Arch of Milky Way."
The starry arc of the Milky Way galaxy sprawls across the evening sky on a spring night in this photo captured near the village of Campinho in Portugal's Dark Sky Alqueva Reserve.
For skywatchers in the Northern Hemisphere, the Milky Way makes its first appearance of the year in spring after hiding beneath the horizon during the winter months. This photo was taken on April 18, 2018 at 3:40 a.m. local time (0230 GMT), about 3 hours before sunrise. [How to See the Milky Way in the Summer Night Sky]
Visible high above the arc of the Milky Way is the bright-blue star Vega, which shines with an apparent magnitude of 0.0 (Vega is used as the standard reference star on the scale of stellar magnitude). Located in the Lyra constellation, Vega forms an asterism, or star pattern, well known as the Summer Triangle along with the stars Deneb (in the Cygnus constellation) and Altair (in the constellation Aquila).
Glowing red just below the right end of the Milky Way's arc is Mars, and Saturn is shining to its right, near the dusty core of the galaxy. Tracing the line formed by Mars and Saturn farther to the right, we can find the red supergiant star Antares in the Scorpius constellation followed by the bright planet Jupiter.
Above the horizon, yellow-green airglow mixes with the lights from the Portuguese village of Aldeia da Luz. Below, water from the Great Lake of Alqueva — the largest man-made lake in Europe — mirrors the starry night sky.
Editor's note: If you captured an amazing astronomy photo and would like to share it with Space.com for a story or gallery, send images and comments to managing editor Tariq Malik at firstname.lastname@example.org.
The HAWC+ image of NGC 1068 shows, for the first time, the magnetized spiral arms of the host galaxy. The forces exerted by the magnetic fields are dominated by rotation of the disk, making the dust grains to be aligned along the spiral arms as they are clearly detected by these HAWC+ polarimetric observations at 53 microns.
Credits: SOFIA/HAWC+/E. Lopez-Rodriguez
Astronomy from the Stratosphere: Results from NASA’s SOFIA Airborne Telescope
The left image shows the large-scale magnetic field along the polar direction of the disk of the starburst galaxy M82. The HAWC+ imaging polarimetric observations show, for the first time, a relatively hot dust magnetically aligned along the direction of the outflows. The right image shows a multi-wavelength view of the galaxy, with the blue x-ray revealing gas that has been heated by the violent outflow.
Astronomers have found a spiral galaxy that may be spinning to the beat of a different cosmic drummer.
To the surprise of astronomers, the galaxy, called NGC 4622, appears to be rotating in the opposite direction to what they expected. Pictures by NASA's Hubble Space Telescope helped astronomers determine that the galaxy may be spinning clockwise by showing which side of the galaxy is closer to Earth. A Hubble telescope photo of the oddball galaxy is this month's Hubble Heritage offering. The image shows NGC 4622 and its outer pair of winding arms full of new stars [shown in blue].
Astronomers are puzzled by the clockwise rotation because of the direction the outer spiral arms are pointing. Most spiral galaxies have arms of gas and stars that trail behind as they turn. But this galaxy has two "leading" outer arms that point toward the direction of the galaxy's clockwise rotation. To add to the conundrum, NGC 4622 also has a "trailing" inner arm that is wrapped around the galaxy in the opposite direction it is rotating. Based on galaxy simulations, a team of astronomers had expected that the galaxy was turning counterclockwise.
NGC 4622 is a rare example of a spiral galaxy with arms pointing in opposite directions. What caused this galaxy to behave differently from most galaxies? Astronomers suspect that NGC 4622 interacted with another galaxy. Its two outer arms are lopsided, meaning that something disturbed it. The new Hubble image suggests that NGC 4622 consumed a small companion galaxy. The galaxy's core provides new evidence for a merger between NGC 4622 and a smaller galaxy. This information could be the key to understanding the unusual leading arms.
Galaxies, which consist of stars, gas, and dust, rotate very slowly. Our Sun, one of many stars in our Milky Way Galaxy, completes a circuit around the Milky Way every 250 million years.
NGC 4622 resides 111 million light-years away in the constellation Centaurus. The pictures were taken in May 2001 with Hubble's Wide Field Planetary Camera 2.
The science team, consisting of Ron Buta and Gene Byrd from the University of Alabama, Tuscaloosa, and Tarsh Freeman of Bevill State Community College in Alabama, observed NGC 4622 in ultraviolet, infrared, and blue and green filters. Their composite image and science findings were presented at the meeting of the American Astronomical Society in January of 2002.
Abell 1033: To Boldly Go into Colliding Galaxy Clusters
Hidden in a distant galaxy cluster collision are wisps of gas resembling the starship Enterprise — an iconic spaceship from the "Star Trek" franchise.
Galaxy clusters — cosmic structures containing hundreds or even thousands of galaxies — are the largest objects in the Universe held together by gravity. Multi-million-degree gas fills the space in between the individual galaxies. The mass of the hot gas is about six times greater than that of all the galaxies combined. This superheated gas is invisible to optical telescopes, but shines brightly in X-rays, so an X-ray telescope like NASA's Chandra X-ray Observatory is required to study it.
casper: I'm back again!!! Maybe this time my computer won't die like it did the last time.
Apr 29, 2018 19:36:04 GMT -6
casper: Skywalker just fixed it. You know what that means. It's doomed.
Apr 29, 2018 19:36:53 GMT -6
skywalker: Very funny, ghost boy
Jun 3, 2018 14:58:58 GMT -6
lois: Casper he should come fix mine. Mine is doomed
Jun 26, 2018 21:54:27 GMT -6
spotless38: Iam back after a long break . What a couple of years I had . After what had happened I lost my brother and had to bury him and then I had caught that type A flue and I was a very sick puppy I also needed blood for the loss of it .
Jul 7, 2018 13:30:41 GMT -6
lois: Very Happy to see you Ron. Missed you. Glad you are doing better now. Sorry for your lost. I did not know your brother had passed. hugs lois
Jul 10, 2018 0:52:45 GMT -6
paulette: Ron - hope you've hit a quiet spot. Sorry for your loss.
Aug 3, 2018 10:49:30 GMT -6
lois: I picked up my phone a few days ago and I looked at the name of the caller. Boy was I surprise. It has been a couple of years. So good to hear your voice Ron. Hope you make it a habit again. love and hugs .
Aug 15, 2018 23:21:38 GMT -6
leia77: Spotless, I am glad that you are feeling better and welcome back! I too am back from a long time away...
Aug 31, 2018 2:08:32 GMT -6
jcurio: I am much relieved to see that you have been on here, Spotless! I hope that things are going much better for you now
Sept 19, 2018 16:46:42 GMT -6
jcurio: And Lois, And Lorelei!
Sept 19, 2018 16:47:07 GMT -6
casper: And Meeeeeee!!
Oct 16, 2018 18:41:31 GMT -6
lois: Sorry guys I cannot see the print. On is tiny hand computer
Oct 21, 2018 20:42:09 GMT -6
lois: Casper your page stops at page five in 2016
Nov 15, 2018 23:54:01 GMT -6
lois: How did your Halloween night go this year?
Nov 15, 2018 23:54:58 GMT -6
skywalker: He posted on the Halloween thread this year.
Nov 25, 2018 18:33:36 GMT -6
lois: Oh ok Sky I will check it out. Thanks.
Dec 21, 2018 21:45:31 GMT -6
lois: What topic was it under.
Dec 21, 2018 21:51:07 GMT -6