Astronomers Identify the Stellar Patrons of the Milky Way Bar
Scientists with the Sloan Digital Sky Survey III (SDSS-III) have announced the discovery of hundreds of stars rapidly moving together in long, looping orbits around the center of our Galaxy. “The best explanation for their orbits is that these stars are part of the Milky Way bar,” says David Nidever, a Dean B. McLaughin Fellow in the Astronomy Department at the University of Michigan. “We know that the bar plays an important role in determining the structure of the Galaxy, so learning more about these stars will help us understand the whole Galaxy, even out here in the spiral arms.”
The team’s discovery came from accurately measuring the speeds of thousands of stars near the center of the Milky Way. The center of our Galaxy is 30,000 light-years away—close by cosmic standards—yet we know surprisingly little about it, because the Galaxy’s dusty disk hides it from view. In spite of this blind spot, though, we do know a key fact about our Galaxy: like many spiral galaxies, the Milky Way has a ‘bar’ of stars that orbit together around the Galactic Center.
IC2220 is the result of the reflection of gas and star material coming ejected from the red giant HD 65750.
The dust emitted from the red star is not displaced equally in all directions. It is thought that the material is distributed via magnetic fields, electric fields or the rotation of the central star giving an irregular shape. Astro photographer David Malin called this object the Toby Jug Nebula after the english drinking vessel. For some others the shape resembles a similarity with a flying butterfly. — Sergio Eguivar
Side Note: The two images shown above are mere crop outs from ESA’s recent hit: The 9 Billion Pixel Image of 84 Million Stars. These two focus on the bright center of the image for the purpose of highlighting what a peak at 84,000,000 stars looks like.
Astronomers at the European Southern Observatory’s Paranal Observatory in Chile have released a breathtaking new photograph showing the central area of our Milky Way galaxy. The photograph shows a whopping 84 million stars in an image measuring 108500×81500, which contains nearly 9 billion pixels.
It’s actually a composite of thousands of individual photographs shot with the observatory’s VISTA survey telescope, the same camera that captured the amazing 55-hour exposure. Three different infrared filters were used to capture the different details present in the final image.
The VISTA’s camera is sensitive to infrared light, which allows its vision to pierce through much of the space dust that blocks the view of ordinary optical telescope/camera systems.
A dwarf planet is a celestial body orbiting the Sun that is massive enough that its shape is controlled by gravitational forces rather than mechanical forces, but has not cleared the neighboring region of other objects.
There are five dwarf planets in our solar system. In ascending orbital radius:
- Ceres, 2.77 AU
- Pluto, 39.48 AU
- Haumea, 43.13 AU
- Makemake, 45.79 AU
- Eris, 67.67 AU
They are imaged above in this order.
Astronomical unit (AU) - the mean distance between the Earth and the Sun. For example, Ceres is 2.77 times farther from the Sun than the Earth.
A new galaxy class has been identified using observations from ESO’s Very Large Telescope (VLT), the Gemini South telescope, and the Canada-France-Hawaii Telescope (CFHT). Nicknamed “green bean galaxies” because of their unusual appearance, these galaxies glow in the intense light emitted from the surroundings of monster black holes and are amongst the rarest objects in the Universe.
Many galaxies have a giant black hole at their centre that causes the gas around it to glow. However, in the case of green bean galaxies, the entire galaxy is glowing, not just the centre. These new observations reveal the largest and brightest glowing regions ever found, thought to be powered by central black holes that were formerly very active but are now switching off.
Astronomer Mischa Schirmer of the Gemini Observatory had looked at many images of the distant Universe, searching for clusters of galaxies, but when he came across one object in an image from the Canada-France-Hawaii Telescope he was stunned — it looked like a galaxy, but it was bright green. It was unlike any galaxy he had ever seen before, something totally unexpected. He quickly applied to use ESO’s Very Large Telescope to find out what was creating the unusual green glow.
“ESO granted me special observing time at very short notice and just a few days after I submitted my proposal, this bizarre object was observed using the VLT,” says Schirmer. “Ten minutes after the data were taken in Chile, I had them on my computer in Germany. I soon refocused my research activities entirely as it became apparent that I had come across something really new.”
The new object has been labelled J224024.1−092748 or J2240. It lies in the constellation of Aquarius (The Water Bearer) and its light has taken about 3.7 billion years to reach Earth.
After the discovery, Schirmer’s team searched through a list of nearly a billion other galaxies and found 16 more with similar properties, which were confirmed by observations made at the Gemini South telescope. These galaxies are so rare that there is on average only one in a cube about 1.3 billion light-years across. This new class of galaxies has been nicknamed green bean galaxies because of their colour and because they are superficially similar to, but larger than, green pea galaxies.
In many galaxies the material around the supermassive black hole at the centre gives off intense radiation and ionises the surrounding gas so that it glows strongly. These glowing regions in typical active galaxies are usually small, up to 10% of the diameter of the galaxy. However, the team’s observations showed that in the case of J2240, and other green beans spotted since, it is truly huge, spanning the entire object. J2240 displays one of the biggest and brightest such regions ever found. Ionised oxygen glows bright green, which explains the strange colour that originally caught Schirmer’s attention.
“These glowing regions are fantastic probes to try to understand the physics of galaxies — it’s like sticking a medical thermometer into a galaxy far, far away,” says Schirmer. “Usually, these regions are neither very large nor very bright, and can only be seen well in nearby galaxies. However, in these newly discovered galaxies they are so huge and bright that they can be observed in great detail, despite their large distances.” — Astronomer Mischa Schirmer of the Gemini Observatory
A gorgeous photo of a star-forming region of space called the Carina Nebula marks the inauguration of a new telescope — the largest instrument in the world devoted to surveying the sky in visible light.
Image: The spectacular star-forming Carina Nebula has been captured in great detail by the VLT Survey Telescope at ESO’s Paranal Observatory. This picture was taken with the help of Sebastián Piñera, President of Chile, during his visit to the observatory on June 5, 2012 and released on the occasion of the new telescope’s inauguration in Naples on Dec. 6, 2012. Credit: ESO. Acknowledgement: VPHAS+ Consortium/Cambridge
The VLT Survey Telescope (VST) at the European Southern Observatory’s Paranal Observatory in Chile was officially inaugurated today (Dec. 6) in Naples, Italy.
While the Carina nebula has been photographed many times before, most telescopes can only observe a small part of it at once. The VST, designed for large surveys of the sky, has a very wide field of view, and was able to image almost all of Carina in a single photo.
Distance: 70,000,000 light-years away in the Constellation Eridanus
The large face-on grand design spiral galaxy NGC 1232 has undoubtedly interacted in complex ways with its smaller irregular companion galaxy NGC 1232A and that interaction has left an indelible mark on the larger galaxy.
The sweeping spiral arms appear to be “bent” in areas rather than the gently curving structures seen in undisturbed spiral galaxies. This aberration of the arms is likely due to gravitational encounters with NGC 1232A as it orbits the larger spiral. Radiowave studies indicate a large envelope of neutral gas extending well beyond the optical extent of the galaxy.
Rotational velocity measurements of the galaxies huge spiral arms suggest a large component of dark matter comprising NGC 1232. NGC1232 spans some 200,000 light years making it almost twice the size of the Milky Way.
If, in some cataclysm, all of scientific knowledge were to be destroyed and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words?
I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms — little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.
In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied"
Astronomers have seen a distant galaxy that blasts away material with two trillion times the energy the sun emits — the biggest such eruption ever seen. That ejection of matter could answer an important question about the universe: why are the black holes in the centers of galaxies so light?
Image: Artist’s impression of the huge outflow ejected from the quasar SDSS J1106+1939 Credit: ESO/L. Calçada
Computer models of the early universe usually produce a virtual cosmos that looks like ours except for one thing. The ratio of the mass of black holes in galaxy centers to the rest of the matter in galaxies is larger in the simulations than in the real universe.
Scientists think somehow galaxies are ridding themselves of much of the mass that would have ended up falling into their central black holes. However, until now researchers have been at a lack for an explanation of how this might happen.
To expel matter from galaxies takes energy. “We needed some input of energy from supermassive black holes,” Nahum Arav, an astrophysicist at Virginia Tech.
Supermassive black holes are obvious candidates, because they are the most energetic objects known. Some galaxies containing active black holes, called quasars, shine more brightly than anything else in the universe. “Our simulations showed that if we allowed the quasar to release a lot of mechanical energy, then the masses of galaxies would match observations,” Arav said.
Arav led a team that observed a quasar, called SDSS J1106+1939, which dates back to when the universe was only 3 billion years old (it is now about 13.7 billion years of age). Most quasars are millions or even billions of light-years distant, which means we see them as they were long ago. As such, they offer a unique window back in time, to when galaxies were young.
NGC 6946, also known as the Fireworks Galaxy, is a face-on spiral galaxy about 10 million light years away beyond a multitude of forground stars within our own galaxy. It spans nearly 40000 light-years across. Nine supernovae have been discovered in NGC 6946 since 1917, which is a sign of an abnormally high star formation rate.
The Milky Way and other galaxies in the universe harbor many young star clusters and associations that each contain hundreds to thousands of hot, massive, young stars known as O and B stars.
The star cluster Cygnus OB2 contains more than 60 O-type stars and about a thousand B-type stars. At a relatively nearby distance to Earth of about 5,000 light years, Cygnus OB2 is the closest massive cluster. Deep observations with NASA’s Chandra X-ray Observatory of Cygnus OB2 have been used to detect the X-ray emission from the hot outer atmospheres, or coronas, of young stars in the cluster and to probe how these great star factories form and evolve.
About 1,700 X-ray sources were detected, including about 1,450 thought to be stars in the cluster. In this image, X-rays from Chandra (blue) have been combined with infrared data from NASA’s Spitzer Space Telescope (red) and optical data from the Isaac Newton Telescope (yellow).
Young stars ranging in age from one million to seven million years were detected. The infrared data indicates that a very low fraction of the stars have circumstellar disks of dust and gas. Even fewer disks were found close to the massive OB stars, betraying the corrosive power of their intense radiation that leads to early destruction of their disks.
Evidence is also seen that the older population of stars has lost its most massive members because of supernova explosions. Finally, a total mass of about 30,000 times the mass of the sun is derived for Cygnus OB2, similar to that of the most massive star forming regions in our Galaxy.
Bok globules are small interstellar clouds of very cold gas and dust that are so thick they are nearly totally opaque to visible light, although they can be studied with infrared and radio techniques.
They were originally discovered as black splotches in front of dense fields of stars, and were even dubbed “holes in the heaven” because they appeared like holes in the stellar background. - [**]
Bok globules are dark clouds of dense cosmic dust and gas in which star formation sometimes takes place. Bok globules are found within H II regions, and typically have a mass of about 2 to 50 solar masses contained within a region about a light year or so across. They contain molecular hydrogen (H2), carbon oxides and helium, and around 1% (by mass) of silicate dust. Bok globules most commonly result in the formation of double or multiple star systems.
Bok globules were first observed by astronomer Bart Bok in the 1940s. In a paper published in 1947, Bok and E.F. Reilly hypothesized that these clouds were ‘similar to insect’s cocoons’ that were undergoing gravitational collapse to form new stars from which stars and star clusters were born. - [**]