Tag: Hubble Space Telescope

15,000 Galaxies in One Image

Astronomers have just assembled one of the most comprehensive portraits yet of the universe’s evolutionary history, based on a broad spectrum of observations by the Hubble Space Telescope and other space and ground-based telescopes.  Each of the approximately 15,000 specks and spirals are galaxies, widely distributed in time and space. (NASA, ESA, P. Oesch of the University of Geneva, and M. Montes of the University of New South Wales)

Here’s an image to fire your imagination: Fifteen thousand galaxies in one picture — sources of light detectable today that were generated as much as 11 billion years ago.

Of those 15,000 galaxies, some 12,000 are inferred to be in the process of forming stars.  That’s hardly surprising because the period around 11 billions years ago has been determined to be the prime star-forming period in the history of the universe.  That means for the oldest galaxies in the image, we’re seeing light that left its galaxy but three billion years after the Big Bang.

This photo mosaic, put together from images taken by the Hubble Space Telescope and other space and ground-based telescopes, does not capture the earliest galaxies detected. That designation belongs to a galaxy found in 2016 that was 420 million years old at the time it sent out the photons just collected. (Photo below.)

Nor is it quite as visually dramatic as the iconic Ultra Deep Field image produced by NASA in 2014. (Photo below as well.)

But this image is one of the most comprehensive yet of the history of the evolution of the universe, presenting galaxy light coming to us over a timeline up to those 11 billion years.  The image was released last week by NASA and supports an earlier paper in The Astrophysical Journal by Pascal Oesch of Geneva University and a large team of others.

And it shows, yet again, the incomprehensible vastness of the forest in which we are a tiny leaf.

Some people apparently find our physical insignificance in the universe to be unsettling.  I find it mind-opening and thrilling — that we now have the capability to not only speculate about our place in this enormity, but to begin to understand it as well.

The Ultra-Deep field composite, which contains approximately 10,000 galaxies.  The images were collected over a nine-year period.  {NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z.

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Of White Dwarfs, "Zombie" Stars and Supernovae Explosions

Artistic view of the aftermath of a supernova explosion, with an unexpected white dwarf remnant. These super-dense but no longer active stars are thought to play a key role in many supernovae explosion. (Copyright Russell Kightley)
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White dwarf stars, the remnant cores of low-mass stars that have exhausted all their nuclear fuel, are among the most dense objects in the sky.
 
Their mass is comparable to that of the sun, while their volume is comparable to that of Earth. Very roughly, this means the average density of matter in a white dwarf would be on the order of 1,000,000 times greater than the average density of the sun.
 
Thought to be the final evolutionary state of stars whose mass is not high enough to become a neutron star — a category that includes the sun and over 97% of the other stars in the Milky Way — they are dim objects first identified a century ago but only in the last decade the subject of broad study.
 
In recent years the white dwarfs have become more and more closely associated with supernovae explosions, though the processes involved remained hotly debated.  A team using the Hubble Space Telescope even captured  before and after images of what is hypothesized to be an incomplete white dwarf supernova.  What was left behind has been described by some as a “zombie star.”
 
Now a team of astronomers led by Stephane Vennes of the Czech Academy of Sciences has detected another zombie white dwarf, LP-40-365 , that they put forward as a far-flung remnant of a long-ago supernova explosion.  This is considered important and unusual because it would represent a first detection of such a remnant long after the supernova conflagration.
 
This dynamic is well captured in an animation accompanying the Science paper that describes the possible remnant.  Here’s the animation and a second-by-second description of what is theorized to have occurred:
 
 
00.0 sec: Initial binary star outside the disk of the Milky Way galaxy. A massive white dwarf accreting
material through an accretion disk from its red giant companion star. The stars orbit around the center of
mass of the binary system.
 
14.6 sec: The white dwarf reaches the Chandrasekhar mass limit and explodes as a bright Type Ia
supernova. However, the explosion is not perfect; a fraction of the white dwarf shoots out like a shrapnel to the left. The binary system disrupts.
 
18.0 sec: The supernova explosion again, at an edge – on view.Read more

Some Spectacular Images (And Science) From The Year Past

A rose made of galaxies

This is a golden era for space and planetary science, a time when discoveries, new understandings, and newly-found mysteries are flooding in.  There are so many reasons to find the drama intriguing:  a desire to understand the physical forces at play, to learn how those forces led to the formation of Earth and ultimately us, to explore whether parallel scenarios unfolded on planets far away, and to see how our burgeoning knowledge might set the stage for exploration.

But always there is also the beauty; the gaudy, the stimulating, the overpowering spectacle of it all.

Here is a small sample of what came in during 2016:

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The Small Magellanic Cloud, a dwarf galaxy that is a satellite of our Milky Way galaxy, can be seen only in the southern hemisphere.  Here, the Hubble Space Telescope captured two nebulas in the cloud. Intense radiation from the brilliant central stars is heating hydrogen in each of the nebulas, causing them to glow red.

Together, the nebulas are called NGC 248 and are 60 light-years long and 20 light-years wide. It is among a number of glowing hydrogen nebulas in the dwarf satellite galaxy, which is found approximately 200,000 light-years away.

The image is part of a study called Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE). Astronomers are using Hubble to probe the Milky Way satellite to understand how dust is different in galaxies that have a far lower supply of heavy elements needed to create that dust.  {NASA.ESA, STSci/K. Sandstrom (University of California, San Diego), and the SMIDGE team}

This picture combines a view of the southern skies over the ESO 3.6-metre telescope at the La Silla Observatory in Chile with images of the stars Proxima Centauri (lower-right) and the double star Alpha Centauri AB (lower-left) from the NASA/ESA Hubble Space Telescope. Proxima Centauri is the closest star to the Solar System and is orbited by the planet Proxima b, which was discovered using the HARPS instrument on the ESO 3.6-metre telescope.

Probably the biggest exoplanet news of the year, and one of the major science stories, involved the discovery of an exoplanet orbiting Proxima Centauri, the star closest to our own.

This picture combines a view of the southern skies over the European Space Observatory’s 3.6-metre telescope at the La Silla Observatory in Chile with images of the stars Proxima Centauri (lower-right) and the double star Alpha Centauri AB (lower-left).

The planet Proxima Centauri b is thought to lie within the habitable zone of its star.  Learning more about the planet, the parent star and the two other stars in the Centauri system has become a focus of the exoplanet community.

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We all know about auroras that light up our far northern skies, but there’s no reason why they wouldn’t exist on other planets shielded by a magnetic field — such as Jupiter. … Read more

More Evidence of Water Plumes On Europa Increases Confidence That They’re For Real

 Figure 2: This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The Hubble data were taken on January 26, 2014. The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions. Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center Image comparison of 2014 transit and 2012 Europa aurora observations


This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The Hubble data were taken on January 2014, and appear to show plumes that spit out as much as 125 miles.  The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions. (NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center)

Europa is a moon no bigger than our own and is covered by deep layers of ice, but it brings with it a world of promise.  Science fiction master and sometimes space visionary Arthur C. Clarke, after all,  named it as the most likely spot in our solar system to harbor life, and wrote a “2001: A Space Odyssey”  follow-up based in part on that premise.

Many in the planetary science and astrobiology communities are similarly inclined and have supported a specifically Europa mission geared to learning more about what is generally considered to be a large ocean beneath that ice.

Along the way, Europa became the only object deemed by Congress to be an obligatory NASA destination, and formal plans for such a voyage have been under way — however slowly — for several years.  Formal development of the “Europa Clipper” flyby project began last year, after a half decade of conceptual work.

The logic for the flyby got a major boost on Monday when a team using the Hubble Space Telescope reported that they had most likely detected plumes of water erupting out of Europa on three separate occasions.

Because of the difficulty of the observation — and the fact that plumes were found on 3 out of 10 passes — nobody was willing to claim that the finding was definitive.  But coupled with an earlier identification of a Europa plume by a different team using a different technique, the probability that the plumes are real is getting pretty high.

And if there really are plumes of water vapor or ice crystals being pushed through Europa’s thick surface of ice, then the implications for the search for signs of habitability and of life on Europa are enormous.

“Europa is surely one of the most compelling astrobiological targets in solar system with its apparent saline oceans,” said William Sparks, an astronomer with Space Telescope Science Institute in Baltimore and lead author of the Europa paper, to be published in The Astrophysical Journal.… Read more

How Will We Know What Exoplanets Look Like, and When?

An earlier version of this article was accidently published last week before it was completed.  This is the finished version, with information from this week’s AAS annual conference.

This image of a pair of interacting galaxies called Arp 273 was released to celebrate the 21st anniversary of the launch of the NASA/ESA Hubble Space Telescope. The distorted shape of the larger of the two galaxies shows signs of tidal interactions with the smaller of the two. It is thought that the smaller galaxy has actually passed through the larger one.

This image of a pair of interacting galaxies called Arp 273 was released to celebrate the 21st anniversary of the launch of the NASA/ESA Hubble Space Telescope. The distorted shape of the larger of the two galaxies shows signs of tidal interactions with the smaller of the two. It is thought that the smaller galaxy has actually passed through the larger one.

Let’s face it:  the field of exoplanets has a significant deficit when it comes to producing drop-dead beautiful pictures.

We all know why.  Exoplanets are just too small to directly image, other than as a miniscule fraction of a pixel, or perhaps some day as a full pixel.  That leaves it up to artists, modelers and the travel poster-makers of the Jet Propulsion Lab to help the public to visualize what exoplanets might be like.  Given the dramatic successes of the Hubble Space Telescope in imaging distant galaxies, and of telescopes like those on the Cassini mission to Saturn and the Mars Reconnaissance Orbiter, this is no small competitive disadvantage.  And this explains why the first picture of this column has nothing to do with exoplanets (though billions of them are no doubt hidden in the image somewhere.)

The problem is all too apparent in these two images of Pluto — one taken by the Hubble and the other by New Horizons telescope as the satellite zipped by.

 

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Pluto image taken by Hubble Space Telescope (above) and close up taken by New Horizons in 2015. (NASA)

Pluto image taken by Hubble Space Telescope (above) and close up taken by New Horizons in 2015. (NASA)

 

Pluto is about 4.7 billion miles away.  The nearest star, and as a result the nearest possible planet, is 25 trillion miles  away.  Putting aside for a minute the very difficult problem of blocking out the overwhelming luminosity of a star being cross by the orbiting planet you want to image,  you still have an enormous challenge in terms of resolving an image from that far away.

While current detection methods have been successful in confirming more than 2,000 exoplanets in the past 20 years (with another 2,000-plus candidates awaiting confirmation or rejection),  they have been extremely limited in terms of actually producing images of those planetary fireflies in very distant headlights.  And absent direct images — or more precisely, light from those planets — the amount of information gleaned about the chemical makeup of their atmospheres  as been limited, too.… Read more

Enceladus and Water Worlds

Glittering geysers of water ice erupt from Saturn's enigmatic moon Enceladus as seen during a previous flyby. The plumes are backlit by the sun, which is almost directly behind the moon. The moon's dark side that we see here is illuminated by reflected Saturn-shine. Today, the Cassini spacecraft flew right through the plumes in order to let its instruments 'taste' them. Credit: NASA/JPL/SSI/Ugarkovich

Glittering geysers of water ice erupt from Saturn’s enigmatic moon Enceladus as seen during a previous flyby. The plumes are back lit by the sun, which is almost directly behind the moon. The moon’s dark side that we see here is illuminated by reflected Saturn-shine.  (NASA/JPL/SSI/Ugarkovich)

As if the prospect of billions of potentially habitable exoplanets wasn’t enough to get people excited, what about all those watery exo-moons too?

The question arises as the Cassini mission makes its final pass near the now famous geysers at the south pole of the moon Enceladus.  The plumes are currently in darkness and so it’s a perfect time to tease out a particularly compelling aspect of the Enceladus story:  how hot is the inside of the mini-moon.  Earlier measurements of the water ice spray took place when the sun was on that southern pole, so this will be the first time Cassini can measure precisely how much of the already detected heat comes from the moon’s interior.

The expectation is that much of the heat does indeed come from inside, warmed substantially by tidal forces and perhaps hydrothermal vents that together serve to keep liquid a subsurface ocean all around the moon.  As a result, the evolving scientific view is that tiny Enceladus, one of 63 moons of Saturn, just may have the ingredients and characteristics that put it into an improbable habitable zone.

“Step by step, we’re learning about an environment that seemed impossible not long ago,” said Cassini Mission Scientist Linda Spilker.  “We know that Enceladus has some rocky core, and that it touches the liquid water.  We also know that some of the compounds identified in the geysers can only be formed when rock is in contact with hot water, and that must be happening at the bottom of the moon’s ocean.  All the pieces are coming together to tell us that the moon has an ocean that might be able to support life.”

 

NASA's Cassini spacecraft captured this view as it neared icy Enceladus for its closest-ever dive past the moon's active south polar region. The view shows heavily cratered northern latitudes at top, transitioning to fractured, wrinkled terrain in the middle and southern latitudes. The wavy boundary of the moon's active south polar region -- Cassini's destination for this flyby -- is visible at bottom, where it disappears into wintry darkness. This view looks towards the Saturn-facing side of Enceladus. North on Enceladus is up and rotated 23 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Oct. 28, 2015. The view was acquired at a distance of approximately 60,000 miles (96,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 45 degrees. Image scale is 1,896 feet (578 meters) per pixel.

The Cassini spacecraft, sponsored by NASA, the European Space Agency and the Italian space Agency,  captured this view on Oct. 28 as it neared Enceladus. The wavy boundary of the moon’s active south polar region — Cassini’s destination for this flyby — is visible at bottom. The image was taken in visible light with the Cassini spacecraft narrow-angle camera from approximately 60,000 miles away. (Cassini Imaging Team, SSI, JPL, ESA, NASA)

 

That a moon might have habitable conditions is not a new idea:  science fiction great Arthur C.… Read more

Faint Worlds On the Far Horizon

Faintest distant galaxy ever detected, formed only 400 million years after the Big Bang. NASA, ESA, and L. Infante (Pontificia Universidad Catolica de Chile)

Faintest distant galaxy ever detected, formed only 400 million years after the Big Bang. NASA, ESA, and L. Infante (Pontificia Universidad Catolica de Chile)

For thinking about the enormity of the canvas of potential suns and exoplanets, I find images like this and what they tell us to be an awkward combination of fascinating and daunting.

This is an image that, using the combined capabilities of NASA’s Hubble and Spitzer space telescopes, shows what is being described as the faintest object, and one of very oldest, ever seen in the early universe.  It is a small, low mass, low luminosity and low size proto-galaxy as it existed some 13.4 billion years ago, about 4oo million years after the big bang.

The team has nicknamed the object Tayna, which means “first-born” in Aymara, a language spoken in the Andes and Altiplano regions of South America.

Though Hubble and Spitzer have detected other galaxies that appear to be slightly further away, and thus older, Tayna represents a smaller, fainter class of newly forming galaxies that until now have largely evaded detection. These very dim bodies may offer new insight into the formation and evolution of the first galaxies — the “lighting of the universe” that occurred after several hundred million years of darkness following the big bang and its subsequent explosion of energy.

This is an illustration by Adolf Schaller from the Hubble Gallery (NASA). It is public domain. It shows colliding protogalaxies less than 1 billion years afer the big bang.

This is an illustration by Adolf Schaller from the Hubble Gallery and shows
colliding protogalaxies less than 1 billion years after the big bang. (NASA)

Detecting and trying to understand these earliest galaxies is somewhat like the drive of paleo-anthropologists to find older and older fossil examples of early man. Each older specimen provides insight into the evolutionary process that created us, just as each discovery of an older, or less developed, early galaxy helps tease out some of the hows and whys of the formation of the universe.

Leopoldo Infante, an astronomer at Pontifical Catholic University of Chile, is the lead author of last week’s Astrophysical Journal article on the faintest early galaxy.  He said there is good reason to conclude there were many more of these earliest proto-galaxies than the larger ones at the time, and that they were key in the “reionization” of the universe — the process through which the universe’s early “dark ages” were gradually ended by the formation of more and more luminous stars and galaxies..

But the process of detecting these very early proto-galaxies is only beginning, he said, and will pick up real speed only when the NASA’s James Webb Space Telescope (scheduled to be launched in 2018) is up and operating. … Read more

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