Why Does The Sombrero Galaxy Look Like a Hat?

Why Does The Sombrero Galaxy Look Like a Hat?

Image Credit: Hubble Heritage Team (AURA/STScI /NASA)

Image Credit: Hubble Heritage Team (AURA/STScI /NASA)

Why does the Sombrero Galaxy look like a hat?

Reasons include the Sombrero’s unusually large and extended central bulge of stars, and dark prominent dust lanes that appear in a disk that we see nearlyedge-on. Billions of old stars cause the diffuse glow of the extended central bulge. Close inspection of the bulge in the above photograph shows many points of light that are actually globular clusters.

M104’s spectacular dust rings harbor many younger and brighter stars, and show intricate details astronomers don’t yet fully understand. The very center of the Sombrero glows across the electromagnetic spectrum, and is thought to house a large black hole. Fifty million-year-old light from the Sombrero Galaxy can be seen with a small telescope towards the constellation of Virgo.

Source: APOD

Mystery Object In Starburst Galaxy M82 Possible Micro-Quasar

Mystery Object In Starburst Galaxy M82 Possible Micro-Quasar

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Radio astronomers at the University of Manchester’s Jodrell Bank Observatory have discovered a strange new object in a nearby galaxy. The object, which appeared very suddenly in radio wavelengths and shows no signs of going away, does not appear to be like anything that has been seen in the Milky Way.  Dr Tom Muxlow will present the discovery at the National Astronomy Meeting in Glasgow on Wednesday 14th April.

The galaxy, known as M82, is 10 million light years away and is a stellar production line churning out new stars at a prodigious rate. However, many of these stars die quickly in huge explosions, with a new supernova explosion occurring every 20 to 30 years.

“The new object, which appeared in May 2009, has left us scratching our heads – we’ve never seen anything quite like this before,” said Dr Muxlow.  “The object turned on very rapidly within a few days and shows no sign of decaying in brightness over the first few months of its existence. The new young supernova explosions that we were expecting to see in M82 brighten at radio wavelengths over several weeks and then decay over several months, so that explanation seems unlikely.”

The plausibility of a supernova explanation was further undermined when very accurate positional monitoring by the UK network of radio telescopes, MERLIN, tentatively detected a change in position for the object over the first 50 days.  This was equivalent to an apparent superluminal motion of over 4 times the speed of light. Such large apparent velocities are not seen in supernova remnants and are usually only found with relativistic jets ejected from accretion disks around massive black hole systems.

The nucleus of M82, like most major galaxies, is expected to contain a super-massive black hole. The new detection lies at a position close to, but several arcseconds from the dynamical centre of M82 – far enough away that it would seem unlikely that this object is associated with the central collapsed core of this galaxy.

The new source could be the first radio detection of an extragalactic ‘micro-quasar’. Examples of such systems within the Milky Way are found as X-ray binaries with relativistic jets ejected from an accretion disk around a collapsed star fuelled with material dragged from a close binary companion. However, this object  would be brighter than any Galactic example yet detected, has lasted months longer than any known X-ray binary, and lies at a position in M82 where no variable X-ray source has been yet been  detected.

If this object is an extragalactic micro-quasar, it would be the first that has been detected at radio wavelengths. The very high luminosity suggests that it is likely to be associated with a massive black hole system of some type; however this and its longevity imply that this type of object is extremely unusual and has not yet been seen within our Galaxy.

“We have just started processing data from an array of 20 radio telescopes across the Earth were taken for the central nuclear region of M82. These images will allow us to examine the structure of the new radio source in detail. However, processing such huge datasets takes significant amounts of computing effort and painstaking work.  Only then will we be able to see if it is some rare form of micro-quasar.   Watch this space…!” said Muxlow.

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The above story is based on materials provided by Royal Astronomical Society (RAS). The original article was written by Anita Heward. Note: Materials may be edited for content and length.

Galactic ‘Rain’ Explains Why Some Galaxies Are Better At Creating Stars

Galactic ‘Rain’ Explains Why Some Galaxies Are Better At Creating Stars

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Some of the galaxies in our universe are veritable star nurseries. For example, our own Milky Way produces, on average, at least one new star every year. Others went barren years ago, now producing few if any new stars.

Why that happens is a question that has dogged astronomers for years. But now, more than 20 years of research by a team led by Michigan State University has culminated in what might be the answer to that elusive question.

According to a study published in the journal Nature, galactic “rain” may be the key to whether a galaxy is fertile.

“We know that precipitation can slow us down on our way to work,” said Mark Voit, an MSU professor of physics and astronomy who led the research team. “Now we know it can also slow down star formation in galaxies with huge black holes.”

Obviously it’s not in the form of rain or snow, but rather cool gas that helps make the creation of stars possible. When conditions are right, these cooling gas clouds help make stars. However, some of the clouds fall into the massive black holes that reside at the center of the galaxy clusters. That triggers the production of jets that reheat the gas like a blowtorch, preventing more stars from forming.

The researchers, using NASA’s Chandra X-ray Observatory, analyzed X-rays from more than 200 galaxy clusters. They could pinpoint how this process of precipitation affects the environment around some of the universe’s largest black holes.

The galaxies within these clusters are surrounded by enormous atmospheres of hot gas that normally would cool and form many stars. However, this is not what astronomers see. Usually there are only feeble amounts of stars forming.

“Something is limiting the rate at which galaxies can turn that gas into stars and planets,” Voit said. “I think we’re finally getting a handle on how this all works.”

While precipitation plays a key role in some galaxies, the researchers found other galaxies where the precipitation had shut off. In these galaxies, the movement of heat around the central galaxy, perhaps due to a collision with another galaxy cluster, likely “dried up” the precipitation around the black hole.

A galaxy cluster can contain anywhere from 50 to 1,000 galaxies. The Milky Way is part of a cluster known as the Local Group, which contains about 50.

In addition to adding to the knowledge of how our universe operates, Voit said research like this helps us all stretch beyond what we thought was possible.

“Astronomy gets people’s attention,” he said. “It makes people curious. It motives them to learn more. What astronomy does is help sustain our culture of discovery.”

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The above story is based on materials provided by Michigan State University. Note: Materials may be edited for content and length.

A Smiling Lens: ‘Happy Face’ Galaxy Cluster Reveals Arcs Caused By Strong Gravitational Lensing

A Smiling Lens: ‘Happy Face’ Galaxy Cluster Reveals Arcs Caused By Strong Gravitational Lensing

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In the centre of this image, taken with the NASA/ESA Hubble Space Telescope, are two faint galaxies that seem to be smiling.

You can make out two orange eyes and a white button nose. In the case of this “happy face”, the two eyes are the galaxies SDSSCGB 8842.3 and SDSSCGB 8842.4 and the misleading smile lines are actually arcs caused by an effect known as strong gravitational lensing.

Massive structures in the Universe exert such a powerful gravitational pull that they can warp the spacetime around them and act as cosmic lenses which can magnify, distort and bend the light behind them. This phenomenon, crucial to many of Hubble’s discoveries, can be explained by Einstein’s theory of general relativity.

In this special case of gravitational lensing, a ring  — known as an Einstein Ring  — is produced from this bending of light, a consequence of the exact and symmetrical alignment of the source, lens and observer and resulting in the ring-like structure we see here.Hubble has provided astronomers with the tools to probe these massive galaxies and model their lensing effects, allowing us to peer further into the early Universe than ever before. This object was studied by Hubble’s Wide Field and Planetary Camera 2 (WFPC2) and Wide Field Camera 3 (WFC3) as part of a survey of strong lenses.

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The above story is based on materials provided by ESA/Hubble Information Centre.Note: Materials may be edited for content and length.