Category Archives: Hubble

Hubble’s Look at M 79

I usually don’t think about Globular clusters in the northern winter except for possibly Messier 79 and just look at this Hubble image

Hubblesite — It’s beginning to look a lot like the holiday season in this NASA Hubble Space Telescope image of a blizzard of stars, which resembles a swirling snowstorm in a snow globe.

The stars are residents of the globular star cluster Messier 79, or M79, located 41,000 light-years from Earth, in the constellation Lepus. The cluster is also known as NGC 1904.

Globular clusters are gravitationally bound groupings of as many as 1 million stars. M79 contains about 150,000 stars packed into an area measuring only 118 light-years across. These giant “star-globes” contain some of the oldest stars in our galaxy, estimated to be 11.7 billion years old.

Most globular clusters are grouped around the central hub of our pinwheel-shaped galaxy. However, M79’s home is nearly on the opposite side of the sky from the direction of the galactic center. One idea for the cluster’s unusual location is that its neighborhood may contain a higher-than-average density of stars, which fueled its formation. Another possibility is that M79 may have formed in an unusual dwarf galaxy that is merging with the Milky Way.

In the Hubble image, Sun-like stars appear yellow. The reddish stars are bright giants that represent the final stages of a star’s life. Most of the blue stars sprinkled throughout the cluster are aging “helium-burning” stars. These bright blue stars have exhausted their hydrogen fuel and are now fusing helium in their cores.

A scattering of fainter blue stars are “blue stragglers.” These unusual stars glow in blue light, mimicking the appearance of hot, young stars. Blue stragglers form either by the merger of stars in a binary system or by the collision of two unrelated stars in M79’s crowded core.

The star cluster was discovered by Pierre Méchain in 1780. Méchain reported the finding to Charles Messier, who included it in his catalog of non-cometary objects. About four years later, using a larger telescope than Messier’s, William Herschel resolved the stars in M79, and described it as a “globular star cluster.”

The image is a combination of observations taken in 1995 and 1997 by Hubble’s Wide Field Planetary Camera 2. The red, green, and blue colors used to compose the image represent a natural view of the cluster.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

Image: NASA and ESA Acknowledgment: S. Djorgovski (Caltech) and F. Ferraro (University of Bologna)

Galactic Wobble

Galactic wobble? Crazy dark matter.

HUBBLE – Using the NASA/ESA Hubble Space Telescope, astronomers have discovered that the brightest galaxies within galaxy clusters “wobble” relative to the cluster’s centre of mass. This unexpected result is inconsistent with predictions made by the current standard model of dark matter. With further analysis it may provide insights into the nature of dark matter, perhaps even indicating that new physics is at work.

Dark matter constitutes just over 25 percent of all mass-energy in the Universe but cannot be directly observed, making it one of the biggest mysteries in modern astronomy. Invisible halos of elusive dark matter enclose galaxies and galaxy clusters alike. The latter are massive groupings of up to a thousand galaxies immersed in hot intergalactic gas. Such clusters have very dense cores, each containing a massive galaxy called the “brightest cluster galaxy” (BCG).

The standard model of dark matter (cold dark matter model) predicts that once a galaxy cluster has returned to a “relaxed” state after experiencing the turbulence of a merging event, the BCG does not move from the cluster’s centre. It is held in place by the enormous gravitational influence of dark matter.

But now, a team of Swiss, French, and British astronomers have analysed ten galaxy clusters observed with the NASA/ESA Hubble Space Telescope, and found that their BCGs are not fixed at the centre as expected [1].

The Hubble data indicate that they are “wobbling” around the centre of mass of each cluster long after the galaxy cluster has returned to a relaxed state following a merger. In other words, the centre of the visible parts of each galaxy cluster and the centre of the total mass of the cluster — including its dark matter halo — are offset, by as much as 40 000 light-years.

“We found that the BCGs wobble around centre of the halos,” explains David Harvey, astronomer at EPFL, Switzerland, and lead author of the paper. “This indicates that, rather than a dense region in the centre of the galaxy cluster, as predicted by the cold dark matter model, there is a much shallower central density. This is a striking signal of exotic forms of dark matter right at the heart of galaxy clusters.”

The wobbling of the BCGs could only be analysed as the galaxy clusters studied also act as gravitational lenses. They are so massive that they warp spacetime enough to distort light from more distant objects behind them. This effect, called strong gravitational lensing, can be used to make a map of the dark matter associated with the cluster, enabling astronomers to work out the exact position of the centre of mass and then measure the offset of the BCG from this centre.

If this “wobbling” is not an unknown astrophysical phenomenon and in fact the result of the behaviour of dark matter, then it is inconsistent with the standard model of dark matter and can only be explained if dark matter particles can interact with each other — a strong contradiction to the current understanding of dark matter. This may indicate that new fundamental physics is required to solve the mystery of dark matter.

Co-author Frederic Courbin, also at EPFL, concludes: “We’re looking forward to larger surveys — such as the Euclid survey — that will extend our dataset. Then we can determine whether the wobbling of BGCs is the result of a novel astrophysical phenomenon or new fundamental physics. Both of which would be exciting!”

Notes

[1] The study was performed using archive data from Hubble. The observations were originally made for the CLASH and LoCuSS surveys.

Image: Hubble (of course)

Galaxy ESO 553-46 – A Busy Place

As far as galaxies are concerned, size can be deceptive. Some of the largest galaxies in the Universe are dormant, while some dwarf galaxies, such as ESO 553-46 imaged here by the NASA/ESA Hubble Space Telescope, can produce stars at a hair-raising rate. In fact, ESO 553-46 has one of the highest rates of star formation of the 1,000 or so galaxies nearest to the Milky Way. No mean feat for such a diminutive galaxy!
Clusters of young, hot stars are speckling the galaxy, burning with a fierce blue glow. The intense radiation they produce also causes surrounding gas to light up, which is bright red in this image. The small mass and distinctive coloring of galaxies of this type prompted astronomers to classify them, appropriately, as blue compact dwarfs (BCD).
Lacking the clear core and structure that many larger galaxies — such as the Milky Way — have, BCDs such as ESO 553-46 are composed of many large clusters of stars bound together by gravity. Their chemical makeup is interesting to astronomers, since they contain relatively little dust and few elements heavier than helium, which are produced in stars and distributed via supernova explosions. Such conditions are strikingly similar to those that existed in the early Universe, when the first galaxies were beginning to form.

Credit: ESA/Hubble & NASA
Text credit: European Space Agency

Hubble and the Coma Cluster

A terrific look at the Coma Cluster, NGC 4874 thanks to Hubble.

ESA/Hubble & NASA — In the center of a rich cluster of galaxies located in the direction of the constellation of Coma Berenices, lies a galaxy surrounded by a swarm of star clusters. NGC 4874 is a giant elliptical galaxy, about ten times larger than the Milky Way, at the center of the Coma Galaxy Cluster. With its strong gravitational pull, it is able to hold onto more than 30,000 globular clusters of stars, more than any other galaxy that we know of, and even has a few dwarf galaxies in its grasp.

In this NASA/ESA Hubble Space Telescope image, NGC 4874 is the brightest object, located to the right of the frame and seen as a bright star-like core surrounded by a hazy halo. A few of the other galaxies of the cluster are also visible, looking like flying saucers dancing around NGC 4874. But the really remarkable feature of this image is the point-like objects around NGC 4874, revealed on a closer look: almost all of them are clusters of stars that belong to the galaxy. Each of these globular star clusters contains many hundreds of thousands of stars.

Recently, astronomers discovered that a few of these point-like objects are not star clusters but ultra-compact dwarf galaxies, also under the gravitational influence of NGC 4874. Being only about 200 light-years across and mostly made up of old stars, these galaxies resemble brighter and larger versions of globular clusters. They are thought to be the cores of small elliptical galaxies that, due to the violent interactions with other galaxies in the cluster, lost their gas and surrounding stars.

This Hubble image also shows many more distant galaxies that do not belong to the cluster, seen as small smudges in the background. While the galaxies in the Coma Cluster are located about 350 million light-years away, these other objects are much farther out. Their light took several hundred million to billions of years to reach us.

This picture was created from optical and near-infrared exposures taken with the Wide Field Channel of Hubble’s Advanced Camera for Surveys. The field of view is 3.3 arcminutes across.

Hubble Spots Comet C/2017 K2

An inbound comet and a record breaker, comet C/2017 K2 PANSTARRS (K2) is still a LONG ways out, perihelion in 2022.

More about C/2017 K2 PANSTARRS (K2).

Thanks to NASA, ESA, and D. Jewitt (UCLA):

A solitary frozen traveler has been journeying for millions of years toward the heart of our planetary system. The wayward vagabond, a city-sized snowball of ice and dust called a comet, was gravitationally kicked out of the Oort Cloud, its frigid home at the outskirts of the solar system. This region is a vast comet storehouse, composed of icy leftover building blocks from the construction of the planets 4.6 billion years ago.

The comet is so small, faint, and far away that it eluded detection. Finally, in May 2017, astronomers using the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii spotted the solitary intruder at a whopping 1.5 billion miles away – between the orbits of Saturn and Uranus. The Hubble Space Telescope was enlisted to take close-up views of the comet, called C/2017 K2 PANSTARRS (K2).

The comet is record-breaking because it is already becoming active under the feeble glow of the distant Sun. Astronomers have never seen an active inbound comet this far out, where sunlight is merely 1/225th its brightness as seen from Earth. Temperatures, correspondingly, are at a minus 440 degrees Fahrenheit. Even at such bone-chilling temperatures, a mix of ancient ices on the surface – oxygen, nitrogen, carbon dioxide, and carbon monoxide – is beginning to sublimate and shed as dust. This material balloons into a vast 80,000-mile-wide halo of dust, called a coma, enveloping the solid nucleus.

Astronomers will continue to study K2 as it travels into the inner solar system, making its closest approach to the Sun in 2022.

NGC 6753 From Hubble

Galaxy NGC 6753, imaged here by the NASA/ESA Hubble Space Telescope, is a whirl of color — the bursts of blue throughout the spiral arms are regions filled with young stars glowing brightly in ultraviolet light, while redder areas are filled with older stars emitting in the cooler near-infrared.

But there is more in this galaxy than meets the Hubble eye. At 150 million light-years from Earth, astronomers highlighted NGC 6753 as one of only two known spiral galaxies that were both massive enough and close enough to permit detailed observations of their coronas. Galactic coronas are huge, invisible regions of hot gas that surround a galaxy’s visible bulk, forming a spheroidal shape. Coronas are so hot that they can be detected by their X-ray emission, far beyond the optical radius of the galaxy. Because they are so wispy, these coronas are extremely difficult to detect.

Galactic coronas are an example of telltale signs astronomers seek to help them determine how galaxies form. Despite the advances made in past decades, the process of galaxy formation remains an open question in astronomy. Various theories have been suggested, but since galaxies come in all shapes and sizes — including elliptical, spiral, and irregular — no single theory has so far been able to satisfactorily explain the origins of all the galaxies we see throughout the Universe.

For more information about Hubble, visit: www.nasa.gov/hubble

Credit: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt
Text credit: European Space Agency

Hubble Looks at NGC-5949

Very nice, first thing I did after seeing this is to go to DSO Browser, a very useful and fun site!

Hubble – The subject of this NASA/ESA Hubble Space Telescope image is a dwarf galaxy named NGC 5949. Thanks to its proximity to Earth — it sits at a distance of around 44 million light-years from us, placing it within the Milky Way’s cosmic neighborhood — NGC 5949 is a perfect target for astronomers to study dwarf galaxies.

With a mass of about a hundredth that of the Milky Way, NGC 5949 is a relatively bulky example of a dwarf galaxy. Its classification as a dwarf is due to its relatively small number of constituent stars, but the galaxy’s loosely-bound spiral arms also place it in the category of barred spirals. This structure is just visible in this image, which shows the galaxy as a bright yet ill-defined pinwheel. Despite its small proportions, NGC 5949’s proximity has meant that its light can be picked up by fairly small telescopes, something that facilitated its discovery by the astronomer William Herschel in 1801.

Astronomers have run into several cosmological quandaries when it comes to dwarf galaxies like NGC 5949. For example, the distribution of dark matter within dwarfs is quite puzzling (the “cuspy halo” problem), and our simulations of the Universe predict that there should be many more dwarf galaxies than we see around us (the “missing satellites” problem).

Credit: ESA/Hubble & NASA
Text credit: European Space Agency

Ultra-Bright Galaxies From Hubble

Light from 8 to 11.5 BILLION years ago. Be sure to click the image to get a larger view or if you want a really large image go to Hubblesite and you can download one for your desktop.

Hubblesite — These six images, taken by the Hubble Space Telescope, reveal a jumble of misshapen-looking galaxies punctuated by exotic patterns such as arcs, streaks, and smeared rings. These unusual features are the stretched shapes of the universe’s brightest infrared galaxies that are boosted by natural cosmic magnifying lenses. Some of the oddball shapes in the images also may have been produced by spectacular collisions between distant, massive galaxies in a sort of cosmic demolition derby.

This so-called gravitational lensing occurs when the intense gravity of a massive galaxy or cluster of galaxies magnifies the light of fainter, more distant background sources. The “lenses” are foreground massive galaxies whose gravity magnifies and distorts images of the distant bright infrared galaxies behind them.

The faraway galaxies are as much as 10,000 times more luminous than our Milky Way. The lensing phenomenon allows for features as small as about 100 light-years or less across to be seen in the background galaxies.

The galaxies existed between 8 billion and 11.5 billion years ago, when the universe was making stars more vigorously than it is today. The galaxies are ablaze with runaway star formation, pumping out more than 10,000 new stars a year. The star-birth frenzy creates lots of dust, which enshrouds the galaxies, making them too faint to detect in visible light. But they glow fiercely in infrared light, shining with the brilliance of 10 trillion to 100 trillion suns.

The infrared galaxies in these images are part of a Hubble survey of 22 distant ultra-luminous infrared galaxies that were found by ground- and space-based observatories. The images were taken in infrared light by Hubble’s Wide Field Camera 3. Color has been added to highlight details in the galaxies.

Hubble Parallel Field

HUBBLE: While one instrument of the NASA/ESA Hubble Space Telescope observed a pair of spiral galaxies for its 27th anniversary last month, another simultaneously observed a nearby patch of the sky to obtain this wide-field view.

These ‘parallel field’ observations increase the telescope’s productivity.

This parallel field shows an area of the sky awash largely with spiral galaxies like our Milky Way. Most of the prominent galaxies look different only because they are tilted at various orientations to our viewpoint – from edge-on to face-on. A few others are interacting or merging.

The image also shows a number of foreground stars in our own galaxy.

Credit: NASA, ESA & M. Mutchler (STScI)

The Lizard

Another great look at an aptly named galaxy and foreground star.

As an aside, I only just realized I apparently had changed a setting and for the past week or so, the images would not show a larger version when they are clicked on. I have corrected the issue and went back for the past week and changed the setting so things work as I intend, including this one.

HUBBLE – In space, being outshone is an occupational hazard. This NASA/ESA Hubble Space Telescope image captures a galaxy named NGC 7250. Despite being remarkable in its own right — it has bright bursts of star formation and recorded supernova explosions— it blends into the background somewhat thanks to the gloriously bright star hogging the limelight next to it.

The bright object seen in this Hubble image is a single and little-studied star named TYC 3203-450-1, located in the constellation of Lacerta (The Lizard). The star is much closer than the much more distant galaxy.

Only this way can a normal star outshine an entire galaxy, consisting of billions of stars. Astronomers studying distant objects call these stars “foreground stars” and they are often not very happy about them, as their bright light is contaminating the faint light from the more distant and interesting objects they actually want to study.

In this case, TYC 3203-450-1 is million times closer than NGC 7250, which lies more than 45 million light-years away from us. If the star were the same distance from us as NGC 7250, it would hardly be visible in this image.

Image credit: ESA/Hubble & NASA
Text credit: European Space Agency