Latest from Hubble: Star Formation Fizzling Out in Nearby Galaxy

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Most galaxies are throughout the universe are happenin’ places, with all sorts of raucous star formation going on. But for a nearby, small spiral galaxy, the star-making party is almost over. In this latest Hubble release, astronomers were surprised to find that star-formation activities in the outer regions of NGC 2976 are fizzling out, and any celebrating is confined to a few die-hard partygoers huddled in the galaxy’s inner region.

The reason? Well, the star birth began when another party-crashing galaxy interacted with NGC 2976. But that happened long ago, and now star formation in the galaxy is fizzling out in the outer parts as some of the gas was stripped away and the rest collapsed toward the center. With no gas left to fuel the party, more and more regions of the galaxy are going to sleep.

“Astronomers thought that grazing encounters between galaxies can cause the funneling of gas into a galaxy’s core, but these Hubble observations provide the clearest view of this phenomenon,” explains astronomer Benjamin Williams of the University of Washington in Seattle, who directed the Hubble study, which is part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. “We are catching this galaxy at a very interesting time. Another 500 million years and the party will be over.”

NGC 2976 does not look like a typical spiral galaxy. It has a star-forming disk, but no obvious spiral pattern. Its gas is centrally concentrated, but it does not have a central bulge of stars. The galaxy resides on the fringe of the M81 group of galaxies, located about 12 million light-years away in the constellation Ursa Major.

“The galaxy looks weird because an interaction with the M81 group about a billion years ago stripped some gas from the outer parts of the galaxy, forcing the rest of the gas to rush toward the galaxy’s center, where it is has little organized spiral structure,” Williams says.

The galaxy’s relatively close distance to Earth allowed Hubble’s Advanced Camera for Surveys (ACS) to resolve hundreds of thousands of individual stars. What look like grains of sand in the image are actually individual stars. Studying the individual stars allowed astronomers to determine their color and brightness, which provided information about when they formed.

The image was taken over a period in late 2006 and early 2007.

“This type of observation is unique to Hubble,” Williams says. “If we had not been able to pick out individual stars, we would have known that the galaxy is weird, but we would not have dug up evidence for a significant gas rearrangement in the galaxy, which caused the stellar birth zone to shrink toward the galaxy’s center.”

Simulations predict that the same “gas-funneling” mechanism may trigger starbursts in the central regions of other dwarf galaxies that interact with larger neighbors. The trick to studying the effects of this process in detail, Williams says, is being able to resolve many individual stars in galaxies to create an accurate picture of their evolution.

Williams’ results will appear in the January 20, 2010 issue of The Astrophysical Journal.

Source: HubbleSite

Hubble Unveils Stunning Star Birth in M83

It appears Hubble’s new Wide Field Camera 3 (WFC3) is working. And how! The new camera installed during Servicing Mission 4 in May has delivered the most detailed view of star birth in the graceful, curving arms of the nearby spiral galaxy M83. Nicknamed the Southern Pinwheel, M83 is undergoing more rapid star formation than our own Milky Way galaxy, especially in its nucleus. The sharp “eye” of WFC3 has captured hundreds of young star clusters, ancient swarms of globular star clusters, and hundreds of thousands of individual stars, mostly blue supergiants and red supergiants.

M83 from ESO and Hubble. Credit for Hubble Image: NASA, ESA, R. O'Connell (University of Virginia), B. Whitmore (Space Telescope Science Institute), M. Dopita (Australian National University), and the Wide Field Camera 3 Science Oversight Committee
M83 from ESO and Hubble. Credit for Hubble Image: NASA, ESA, R. O'Connell (University of Virginia), B. Whitmore (Space Telescope Science Institute), M. Dopita (Australian National University), and the Wide Field Camera 3 Science Oversight Committee

The image at right is Hubble’s close-up view of the myriad stars near the galaxy’s core, the bright whitish region at far right. An image of the entire galaxy, taken by the European Southern Observatory’s Wide Field Imager on the ESO/MPG 2.2-meter telescope at La Silla, Chile, is shown at left. The white box outlines Hubble’s view.

WFC3’s broad wavelength range, from ultraviolet to near-infrared, reveals stars at different stages of evolution, allowing astronomers to dissect the galaxy’s star-formation history.

Now that’s the birth of a star!

See more views of M83 and a video at the HubbleSite

New Hubble Release: Dramatic Galaxy Collision

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At first glance, this latest image release from Hubble appears to be one really bizarre-looking galaxy. But actually, this is a pair of spiral galaxies that resemble our own Milky Way smashing together at breakneck speeds. The centers have already merged into one nucleus, and the two tidal tails stretching out from the center are sparkling with active star formation, prompted by the exchange of mass and gases from the dramatic collision. This object, NGC 2623, or Arp 243, is about 250 million light-years away in the constellation of Cancer (the Crab), and is in the late stages of the merging process.

The prominent lower tail is richly populated with bright star clusters — 100 of them have been found in these observations. The large star clusters that the team has observed in the merged galaxy are brighter than the brightest clusters we see in our own vicinity. These star clusters may have formed as part of a loop of stretched material associated with the northern tail, or they may have formed from debris falling back onto the nucleus. In addition to this active star-forming region, both galactic arms harbor very young stars in the early stages of their evolutionary journey.

Watch this video for more information on NGC 2623:

Some mergers (including NGC 2623) can result in an active galactic nucleus, where one of the supermassive black holes found at the centers of the two original galaxies is stirred into action. Matter is pulled toward the black hole, forming an accretion disc. The energy released by the frenzied motion heats up the disc, causing it to emit across a wide swath of the electromagnetic spectrum.

NGC 2623 is so bright in the infrared that it belongs to the group of very luminous infrared galaxies (LIRG) and has been extensively studied as the part of the Great Observatories All-sky LIRG Survey (GOALS) project that combines data from Hubble, the Spitzer Space Telescope, Chandra X-ray Observatory and the Galaxy Evolution Explorer (GALEX). The combination of resources is helping astronomers characterize objects like active galactic nuclei and nuclear star formation by revealing what is unseen at visible wavelengths.

The data used for this color composite were actually taken in 2007 by the Advanced Camera for Surveys (ACS) aboard Hubble, but is just being released now, as a team of over 30 astronomers, led by Aaron S. Evans, recently published an overview paper, detailing the first results of the GOALS project. Observations from ESA’s X-ray Multi-Mirror Mission (XMM-Newton) telescope contributed to the astronomers’ understanding of NGC 2623.

NGC 2623 paper
GOALS Overview paper
GOALS website

Source: European Hubble website

Hubble’s Amazing Rescue on NOVA



In a world where you have just one chance to save a dying explorer, the only hope is a space shuttle mission …(said in my deepest, most dramatic voice….) Enjoy this movie-like trailer for the upcoming NOVA special on PBS stations in the US, “Hubble’s Amazing Rescue.” It looks like a great show, providing the chance to re-live the exciting 12-day Hubble Servicing Mission 4 and its five pressure-filled spacewalks. Hubble’s Amazing Rescue premieres Tuesday, October 16th at 8PM ET/PT on PBS. Find out more about the show and check local listings for your area here.

Hubble Sees Galaxies Stripped by Ram Pressure

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Strange forces of nature are stripping away gas from galaxies in the Virgo cluster. An extremely hot X-ray emitting gas known as the intra-cluster medium permeates the regions between galaxies inside clusters and, as fast moving galaxies whip through this medium, strong winds tear through galaxies distorting their shape and even halting star formation with a process known as “ram pressure stripping.” Hubble spied two galaxies “losing it” to these forces.

Ram pressure is the drag force that results when something moves through a fluid — much like the wind you feel in your face when bicycling, even on a still day — and occurs in this context as galaxies orbiting about the centre of the cluster move through the intra-cluster medium, which then sweeps out gas from within the galaxies.

The two galaxies — NGC 4522 and NGC 4402 – were imaged by the old Advanced Camera for Surveys on Hubble before it suffered from a power failure in 2007. Astronauts on Servicing Mission 4 in May 2009 were able to restore ACS during their 13-day mission.

This image shows NGC 4522 within the context of the Virgo Cluster.   Credit: NASA, ESA and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)
This image shows NGC 4522 within the context of the Virgo Cluster. Credit: NASA, ESA and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

The spiral galaxy NGC 4522 is located some 60 million light-years away from Earth and it is a spectacular example of a spiral galaxy currently being stripped of its gas content. Astronomers estimate the galaxy is moving at more than 10 million kilometers per hour, and its rapid motion within the cluster results in strong winds across the galaxy as the gas within is left behind. A number of newly formed star clusters that developed in the stripped gas can be seen in the Hubble image.

The image provides a vivid view of the ghostly gas being forced out of it. Bright blue pockets of new star formation can be seen to the right and left of centre. The image is sufficiently deep to show distant background galaxies.

The image of NGC 4402 also highlights some telltale signs of ram pressure stripping such as the curved, or convex, appearance of the disc of gas and dust, a result of the forces exerted by the heated gas. Light being emitted by the disc backlights the swirling dust that is being swept out by the gas. Studying ram pressure stripping helps astronomers better understand the mechanisms that drive the evolution of galaxies, and how the rate of star formation is suppressed in very dense regions of the Universe like clusters.

Source: Hubble Science Center

Hubble Ultra Deep Field in 3-D


Here’s a new way to appreciate the Hubble Ultra Deep Field image, by flying through the 10,000 galaxies in this deepest of all Hubble images. Watch the whole video if you need the background on the Hubble Deep Field and subsequent Ultra Deep Field. Start at about 3:00 if you just want to see the distances between the galaxies in this image. Nice.

Via Gizmodo

Hubble Powers Up to Capture Jupiter Impact Site

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The Hubble Space Telescope was undergoing a thorough checkout of all its systems following the recent servicing mission, but scientists decided to drop everything and interrupt the observatory’s checkout and calibration to take an image of what every other telescope has by trying to view: the impact site on Jupiter. But Hubble does it better than anyone. This image, taken just yesterday (July 23) shows the black spot on the giant planet — created a small comet or asteroid — is expanding.

“Because we believe this magnitude of impact is rare, we are very fortunate to see it with Hubble,” said Amy Simon-Miller of NASA’s Goddard Space Flight Center in Greenbelt, Md. “Details seen in the Hubble view shows a lumpiness to the debris plume caused by turbulence in Jupiter’s atmosphere.”

The new Hubble images also confirm that the May servicing visit by space shuttle astronauts was a big success.

The Jupiter impact has been a sensation ever since Australian amateur astronomer Anthony Wesley imaged a black spot on the planet on July 19. , The only other time such a feature has been seen on Jupiter was 15 years ago after the collision of fragments from comet Shoemaker-Levy 9.

For the past several days, Earth-based telescopes have been trained on Jupiter. To capture the unfolding drama 360 million miles away, Matt Mountain, director of the Space Telescope Science Institute in Baltimore, gave observation time to a team of astronomers led by Heidi Hammel of the Space Science Institute in Boulder, Colo.

“Hubble’s truly exquisite imaging capability has revealed an astonishing wealth of detail in the impact site,” Hammel said. “By combining these images with our ground-based data at other wavelengths, our Hubble data will allow a comprehensive understanding of exactly what is happening to the impact debris.”

Simon-Miller estimated the diameter of the impacting object was the size of several football fields. The force of the explosion on Jupiter was thousands of times more powerful than the suspected comet or asteroid that exploded over the Siberian Tunguska River Valley in June 1908.

The image was taken with the Wide Field Camera 3. The new camera, installed by the astronauts aboard space shuttle Atlantis in May, is not yet fully calibrated. While it is possible to obtain celestial images, the camera’s full power has yet to be seen.

“This is just one example of what Hubble’s new, state-of-the-art camera can do, thanks to the STS-125 astronauts and the entire Hubble team,” said Ed Weiler, associate administrator of NASA’s Science Mission Directorate in Washington. “However, the best is yet to come.”

Source: NASA

Hubble Image of the Colliding Antennae Galaxies (with Video)

It’s time for another beautiful image from the Hubble Space Telescope. And this time, there’s an added bonus… video. The latest images released by Hubble are based on research of the Antennae Galaxies, known as NGC 4038 and NGC 4039. Astronomers used to think that they were 65 million light-years away, but the new research puts them much closer; probably 45 million light-years away.

This image was captured by Hubble’s Advanced Camera for Surveys and Wide Field Planetary Camera 2, to observe individual stars spawned by the cosmic collision.

Here’s the Hubble video to help you get a sense of the scales involved (with pretty music too).

The astronomers targeted the object’s southern tidal tail, which was thrown away from the active central regions. This tail contains material hurled away from the main galaxies as they came together. Astronomers looked for older red giants to make the estimate for their distance. These red giants are known to always shine with the same brightness, and by knowing this brightness, they were able to calculate the galaxies as being 45 million light-years away.

Since this galactic merger is happening relatively close, it’s one of the best examples astronomers have to study this process. And now that the galaxies are closer than astronomers previously believed, it changes the size of many objects the astronomers are studying. For example, the size of the star clusters being formed by the collision match the size of other galaxy mergers, instead of being 1.5 times larger than they should be.

The Antennae Galaxies are named for the two long tails of stars, gas and dust thrown out of the collision that resemble the antennae of insects. They can be found in the constellation of Corvus, the Crow.

Original Source: Hubble News Release