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Category: Galaxies (page 2 of 2)

Some Spectacular Images (And Science) From The Year Past

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:

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}

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.

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

Out Of The Darkness

September 21, 2016 / Marc Kaufman / 0 Comments

Simulation of the "Dark Ages," a period between 380,000 years and 4 million years after the Big Bang. The universe was made up primarily of hydrogen in a neutral state, which did not easily connect with any other particles. NASA/WMAP

Simulation of the “Dark Ages” of the universe, a period predicted by theorists to have lasted as long as several hundred million years after the Big Bang. The first hydrogen atoms in the universe had not yet coalesced into stars and galaxies. (NASA/WMAP)

Before there were planets in our solar system, there was a star that would become our sun. Before there was a sun, there were older stars and exoplanets throughout the galaxies.

Before there were galaxies with stars and exoplanets, there were galaxies with stars and no planets. Before there were galaxies without planets, there were massive singular stars.

And before that, there was darkness for more than 100 million years after the Big Bang — a cosmos without much, or at times any, light.

So how did the lights get turned on, setting the stage for all that followed? Scientists have many theories but so far only limited data.

In the coming years, that is likely to change substantially.

First, the James Webb Space Telescope, scheduled to launch in 2018, will be able to look back at distant galaxies and stars that existed in small or limited numbers during the so called Dark Ages. They gradually became more prevalent and then suddenly (in astronomical terms) became common. Called the epoch of cosmic “reionization,” this period is an essential turning point in the evolution of the cosmos.

Less well known but also about to begin pioneering work into how and when the lights came on will be an international consortium led by a team at the University of California, Berkeley. Unlike the space-based JWST, this effort will use an array of radio telescopes under construction in the South African desert. The currently small array will expand quickly now thanks in large part to a $9.6 million grant recently announced from the National Science Foundation.

Named the Hydrogen Epoch of Reionization Array (HERA), the project will focus especially on the billion-year process that changed the fundamental particle physics of the universe to allow stars, galaxies and their light burst out like spring flowers after a long winter. But unlike the JWST, which will be able to observe faint and very early individual galaxies and stars, HERA will be exploring the early universe as a near whole.

Before stars and galaxies became common, the universe went through a long period of darkness and semi-darkness, but ended with the “Epoch of Reionization.”

Earth: A Prematurely Inhabited Planet?

August 22, 2016 / Marc Kaufman / 0 Comments

A schematic of the history of the cosmos since the Big Bang identifies the period when planets began to form, but there's indication of when life might have started. Harvard's Avi Loeb wants to put life into this cosmological map, and foresees much more of it in the future, given certain conditions. ( NASA)

A schematic of the history of the cosmos since the Big Bang identifies the period when planets began to form, but there’s no indication of when life might have started. Harvard’s Avi Loeb wants to add life into this cosmological map, and foresees much more of it in the future, given certain conditions. ( NASA)

The study of the formation and logic of the universe (cosmology) and the study of exoplanets and their conduciveness to life do not seem to intersect much. Scientists in one field focus on the deep physics of the cosmos while the others search for the billions upon billions of planets out there and seek to unlock their secrets.

But astrophysicist and cosmologist Avi Loeb — a prolific writer about the early universe from his position at the Harvard-Smithsonian Center for Astrophysics– sees the two fields of study as inherently connected, and has set out to be a bridge between them. The result was a recent theoretical paper that sought to place the rise of life on Earth (and perhaps elsewhere) in cosmological terms.

His conclusion: The Earth may well be a very early example of a living biosphere, having blossomed well before life might be expected on most planets. And in theoretical and cosmological terms, there are good reasons to predict that life will be increasingly common in the universe as the eons pass.

By eons here, Loeb is thinking in terms that don’t generally get discussed in geological or even astronomical terms. The universe may be an ancient 13.7 billion years old, but Loeb sees a potentially brighter future for life not billions but trillions of years from now. Peak life in the universe, he says, may arrive several trillion years hence.

“We used the most conservative approaches to understanding the appearance of life in the universe, and our conclusion is that we are very early in the process and that it is likely to ramp up substantially in the future,” said Loeb, whose paper was published in the Journal of Cosmology and Astroparticle Physics.

“Given the factors we took into account, you could say that life on Earth is on the premature side.”

The Earth was formed some 4.5 billions years ago, and life that existed as long ago as 3.5 to 3.8 billion years ago has been discovered. Harvard astrophysicist Avi Loeb argues that life on Earth may well be "premature" in cosmological terms, and that many more planets will have biospheres in the far future. (xxx)

The Earth was formed some 4.5 billion years ago, and signs of life have been discovered that are 3.5 to 3.8 billion years old. Harvard astrophysicist Avi Loeb, with co-authors Rafael Batista and David Sloan of the University of Oxford, argue that life on Earth may well be “premature” in cosmological terms, and that many more planets will have biospheres in the far future.

The Ever More Puzzling, And Intriguing, "Tabby’s Star."

August 8, 2016 / Marc Kaufman / 0 Comments

Did Tabby’s star going through periodic and deep dimmings because of dust and debris clouds that pass edbetween it and the mirror of the Kepler Space Telescope? That was an earlier explanation for the highly unusual behavior of the star, but new research makes that answer less likely. Artist drawing by NASA/JPL-Caltech/T. Pyle

Substantial, sun-like stars are not supposed to dim. They start with gravity and pressure induced nuclear reactions, and then they burn brighter and brighter until they either explode (go supernova) or burn all their fuel and become small, enormously dense, and not very bright “white dwarfs.”

Of course, the transit technique of searching for exoplanets looks precisely for dimmings — of stars caused by the passage of an exoplanet. But those are tiny reductions in the star’s brightness and short-lived. So if a star is dimming significantly over a much longer period of time, something unusual is going on.

And that is apparently exactly what is happening with the current poster child for mysterious stars — KIC 8462852 or “Tabby’s star,” named after the Yale University postdoc who, with the help of citizen scientists, discovered it, Tabetha Boyajian.

First written up last fall, the big news was data from the Kepler Space Telescope showed that the star had experienced two major and dissimilar dips in brightness — a highly unusual and perplexing phenomenon. The dips appeared much too large to represent the passage of an exoplanet, so explanations tended towards the baroque — a swarm of comets, a vast dust cloud, even an alien megastructure (proposed as a last possible explanation.) The observation was first identified by citizen planet hunters working with Boyajian, making it an even more compelling finding.

Now the mystery has grown stranger still. A paper made public last week based on a different kind of Kepler imaging (full-frame imaging) found not two but one enormous dip in the light curve, as well as a surprising and significant dimming the of star over the four year observing period of the space telescope. The paper has been submitted for publication in American Astronomical Society journals.

Benjamin Montet of Caltech and Joshua Simon of the Observatories of the Carnegie Institution of Washington, analyzed the full-field images taken by Kepler every three months (rather than the hourly images studied by Boyajian et al,) and concluded that something strange was indeed going on.

Their conclusion: “No known or proposed stellar phenomena can fully explain all aspects of the observed light curve.”… Read more

The Still Mysterious "Tabby’s Star"

June 3, 2016 / Marc Kaufman / 0 Comments

Artist rendering of star xxx, and the unexplain ed objects close to it. KNown as "Tabby's" star

Artist rendering of dusty comets approaching star KIC8462852, an interpretation of the mysterious objects that periodically block out substantial amounts of the star’s light. Known informally as “Tabby’s” star, it was discovered by citizen scientists using Kepler Space Telescope data, and they are looking for ways to continue their work. (NASA/JPL-Caltech)

It’s been eight months since citizen “Planet Hunters” working with Yale postdoc Tabetha Boyajian announced the discovery of a most unusual star, or rather a star where something most unusual was intermittently and erratically happening.

The puzzle began with some light curve data, taken over a four year period, by the Kepler Space Telescope The citizen planet hunters pored through reams of data sent back by Kepler looking for signals of planetary transits — the ever-so-slight dimmings of the star caused by the crossing or an orbiting exoplanet.

But the light curve for KIC 8462852 showed dimmings that were anything but slight, and anything but regular. The Planet Hunters flagged the star for Boyajian’s groups attention, and the mystery star was born.

Theories on what was causing the very large dips ranged from a host of enormous comets, to a violently exploding planet, to an asteroid belt or the presence of close by stars, from an artifact of Kepler’s camera to, finally, an alien megastructure. (The last was offered by Penn State astronomer Jason Wright as a kind of “Hail Mary” explanation if and when the others are found wanting. But that’s what got the press.)

Despite years of concerted observing, theorizing and analyzing, Boyajian, Wright the citizen planet hunters and others intrigued by the mystery say they are no closer to an explanation for whatever is passing in front of the star (now informally called “Tabby’s star.”) NASA has ruled out a technical glitch in the Kepler data, and a range of astronomers have found fault with all the explanations put forward.

But while the quite tantalizing mystery remains, efforts to learn more about the star may have to wind down soon. The primary Kepler mission is over, so it will provide no more data for this star. Other space telescopes will not be looking, nor will the major ground-based observatories. And the first SETI searches for signals coming from the star has found nothing unusual.

So with options dwindling to learn more, Boyajian, her citizen astronomers and others have begun a grassroots effort to raise $100,000 to buy time at a network of smaller ground-based telescopes around the world.… Read more

Shredding Exoplanets, And The Mysteries They May Unravel

February 15, 2016 / Marc Kaufman / 0 Comments

In this artist’s conception, a tiny rocky object vaporizes as it orbits a white dwarf star. Astronomers have detected the first planetary object transiting a white dwarf using data from the K2 mission. Slowly the object will disintegrate, leaving a dusting of metals on the surface of the star. (NASA)

In this artist’s conception, a small planet or planetesimal vaporizes as it orbits close to a white dwarf star. The detection of several of these disintegrating planets around a variety of stars has led some astronomers to propose intensive study of their ensuing dust clouds as a surprising new way to learn about the interiors of exoplanet. (NASA)

One of the seemingly quixotic goals of exoplanet scientists is to understand the chemical and geo-chemical compositions of the interiors of the distant planets they are finding. Learning whether a planet is largely made up of silicon or magnesium or iron-based compounds is essential to some day determining how and where specific exoplanets were formed in their solar systems, which ones might have the compounds and minerals believed to be necessary for life, and ultimately which might actually be hosting life.

Studying exoplanet interiors is a daunting challenge for sure, maybe even more difficult in principle than understanding the compositions of exoplanet atmospheres. After all, there’s still a lot we don’t know about the make-up of planet interiors in our own solar system.

An intriguing pathway, however, has been proposed based on the recent discovery of exoplanets in the process of being shredded. Generally orbiting very close to their suns, they appear to be disintegrating due to intense radiation and the forces of gravity.

And the result of their coming apart is that their interiors, or at least the dust clouds from their crusts and mantles, may well be on display and potentially measurable.

“We know very little for sure about these disintegrating planets, but they certainly seem to offer a real opportunity,” said Jason Wright, an astrophysicist at Pennsylvania State University with a specialty in stellar astrophysics. No intensive study of the dusty innards of a distant, falling-apart exoplanet has been done so far, he said, but in theory at least it seems to be possible.

Artist’s impression of disintegrating exoplanet KIC 12255 (C.U Keller, Leiden University)

Artist’s impression of disintegrating exoplanet KIC 12557548, the first of its kind ever detected. (C.U Keller, Leiden University)

And if successful, the approach could prove broadly useful since astronomers have already found at least four of disintegrating planets and predict that there are many more out there. The prediction is based on, among other things, the relative speed with which the planets fall apart. Since the disintegration has been determined to take only tens of thousands to a million years (a very short time in astronomical terms) then scientists conclude that the shreddings must be pretty common –based on the number already caught in the act.… Read more

The Borderland Where Stars and Planets Meet

December 15, 2015 / Marc Kaufman / 0 Comments

Brown dwarfs — like the one illustrated here – are more massive and hotter than planets but lack the mass required to become sizzling stars. Their atmospheres can be similar to Jupiter’s, with wind-driven, planet-size clouds. (NASA/JPL-Caltech)

Results from two very different papers in recent weeks have brought home one of the more challenging and intriguing aspects of large exoplanet hunting: that some exoplanets the mass of Jupiter and above share characteristics with small, cool stars. And as a result, telling the two apart can sometimes be a challenge.

This conclusion does not come from new discoveries per se and has been a subject of some debate for a while. But that borderland is becoming ever more tangled as discoveries show it to be ever more populated.

The first paper in The Astrophysical Journal described the first large and long-lasting “spot” on a star, a small and relatively cool star (or perhaps “failed star”) called an L dwarf. The feature was similar enough in size and apparent type that it was presented as a Jupiter-like giant red spot. Our solar system’s red spot is pretty well understood and the one on star W1906+40 certainly is not. But the parallels are nonetheless thought-provoking.

“To my mind, there are important similarities between what we found and the red spot on Jupiter,” said astronomer John Gizis of the University of Delaware, Newark. “Both are fundamentally the result of clouds, of winds and temperature changes that create huge dust clouds. The Jupiter storm has been going for four hundred years and this one, well we know with Hubble and Spitzer that it been there for two years, but it’s probably more.”

A far cry from 400 years, but the other similar storms and spots identified have been on brown dwarfs — failed stars that start hot and burn out over a relatively short time. Gizis said some large storms have been detected on them but that they’re gone in a few days.

The dust and wind storm on the L dwarf W1906+40 rotates around the cool star every nine hours and is large enough to hold three Earths. L-dwarfs mark the boundary between real stars and “failed stars.” . Most known L dwarfs are brown dwarfs, also known as “failed stars” because they never sustain atomic fusion, but the most massive L dwarfs can fuse hydrogen atoms and generate energy like our sun.

Faint Worlds On the Far Horizon

December 7, 2015 / Marc Kaufman / 0 Comments

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

Many Worlds

Category: Galaxies (page 2 of 2)

Some Spectacular Images (And Science) From The Year Past

Out Of The Darkness

Earth: A Prematurely Inhabited Planet?

The Ever More Puzzling, And Intriguing, "Tabby’s Star."

The Still Mysterious "Tabby’s Star"

Shredding Exoplanets, And The Mysteries They May Unravel

The Borderland Where Stars and Planets Meet

Faint Worlds On the Far Horizon

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