There’s more to a galaxy than meets the eye. Galaxies’ bright stars seem to spiral serenely against the dark backdrop of space. But a more careful look reveals a whole lot of mayhem.
“Galaxies are just like you and me,” Jessica Werk, an astronomer at the University of Washington in Seattle, said in January at a meeting of the American Astronomical Society. “They live their lives in a constant state of turmoil.”
Much of that turmoil takes place in a huge, complicated setting called the circumgalactic medium, or CGM. This vast, roiling cloud of dust and gas is a galaxy’s fuel source, waste dump and recycling center all in one. Astronomers think the answers to some of the most pressing galactic mysteries — how galaxies keep forming new stars for billions of years, why star formation abruptly stops — are hidden in a galaxy’s enveloping CGM.
“To understand the galaxies, you have to understand the ecosystem that they’re in,” says astronomer Molly Peeples of the Space Telescope Science Institute in Baltimore.
Yet this galactic atmosphere is so diffuse that it’s invisible — a liter of CGM contains just a single atom. It has taken almost 60 years and an upgrade to the Hubble Space Telescope just to begin probing distant CGMs and figuring out how their constant churning can make or break galaxies. [Continue reading…]
The ecosystem that controls a galaxy’s future — its circumgalactic medium — is coming into focus
First sighting of a newborn planet
It is a moment of birth that has previously proved elusive, but astronomers say they now have the first confirmed image of the formation of a planet.
The startling snapshot shows a bright blob – the nascent planet – travelling through the dust and gas surrounding a young star, known as PDS70, thought to be about 370 light years from Earth.
The black circle in the centre of the image, to the left of the planet, is a filter to block the light from the star, enabling other features of the system to be seen.
Captured by the Sphere instrument of the European Southern Observatory’s Very Large Telescope, the planet – a gas giant with a mass greater than Jupiter – is about as far from its star as Uranus is from our sun, with further analyses revealing that it appears to have a cloudy atmosphere and a surface temperature of 1000C. [Continue reading…]
Space is full of dirty, toxic grease, scientists reveal
It looks cold, dark and empty, but astronomers have revealed that interstellar space is permeated with a fine mist of grease-like molecules.
The study provides the most precise estimate yet of the amount of “space grease” in the Milky Way, by recreating the carbon-based compounds in the laboratory. The Australian-Turkish team discovered more than expected: 10 billion trillion trillion tonnes of gloop, or enough for 40 trillion trillion trillion packs of butter.
Prof Tim Schmidt, a chemist at the University of New South Wales, Sydney and co-author of the study, said that the windscreen of a future spaceship travelling through interstellar space might be expected to get a sticky coating.
“Amongst other stuff it’ll run into is interstellar dust, which is partly grease, partly soot and partly silicates like sand,” he said, adding that the grease is swept away within our own solar system by the solar wind.
The findings bring scientists closer to figuring out the total amount of carbon in interstellar space, which fuels the formation of stars, planets and is essential for life. [Continue reading…]
The next big discovery in astronomy? Scientists probably found it years ago – but they don’t know it yet
NASA/JPL-Caltech
By Eileen Meyer, University of Maryland, Baltimore County
Earlier this year, astronomers stumbled upon a fascinating finding: Thousands of black holes likely exist near the center of our galaxy.
The X-ray images that enabled this discovery weren’t from some state-of-the-art new telescope. Nor were they even recently taken – some of the data was collected nearly 20 years ago.
No, the researchers discovered the black holes by digging through old, long-archived data.
Discoveries like this will only become more common, as the era of “big data” changes how science is done. Astronomers are gathering an exponentially greater amount of data every day – so much that it will take years to uncover all the hidden signals buried in the archives.
The evolution of astronomy
Sixty years ago, the typical astronomer worked largely alone or in a small team. They likely had access to a respectably large ground-based optical telescope at their home institution.
Their observations were largely confined to optical wavelengths – more or less what the eye can see. That meant they missed signals from a host of astrophysical sources, which can emit non-visible radiation from very low-frequency radio all the way up to high-energy gamma rays. For the most part, if you wanted to do astronomy, you had to be an academic or eccentric rich person with access to a good telescope.
Old data was stored in the form of photographic plates or published catalogs. But accessing archives from other observatories could be difficult – and it was virtually impossible for amateur astronomers.
Today, there are observatories that cover the entire electromagnetic spectrum. No longer operated by single institutions, these state-of-the-art observatories are usually launched by space agencies and are often joint efforts involving many countries.
With the coming of the digital age, almost all data are publicly available shortly after they are obtained. This makes astronomy very democratic – anyone who wants to can reanalyze almost any data set that makes the news. (You too can look at the Chandra data that led to the discovery of thousands of black holes!)
Colossal cosmic collision alters understanding of early universe
Astronomers have detected the early stages of a colossal cosmic collision, observing a pile-up of 14 galaxies 90 percent of the way across the observable universe in a discovery that upends assumptions about the early history of the cosmos.
Researchers said on Wednesday the galactic mega-merger observed 12.4 billion light-years away from Earth occurred 1.4 billion years after the Big Bang that gave rise to the universe. Astronomers call the object a galactic protocluster, a precursor to the type of enormous galaxy clusters that are the largest-known objects in today’s universe.
It marked the first time scientists observed the birth of a galaxy cluster, with at least 14 galaxies crammed into an area only about four times the size of our average-sized Milky Way galaxy.
A protocluster as massive as the one observed here, designated as SPT2349-56, should not have existed at that time, according to current notions of the early universe. Scientists had figured this could not happen until several billion of years later. [Continue reading…]
Don’t miss the latest posts at Attention to the Unseen: Sign up for email updates.
Gaia mission releases map of more than a billion stars – here’s what it can teach us
ESA/Gaia/DPAC, CC BY-SA
By George Seabroke, UCL
Most of us have looked up at the night sky and wondered how far away the stars are or in what direction they are moving. The truth is, scientists don’t know the exact positions or velocities of the vast majority of the stars in the Milky Way. But now a new tranche of data from the European Space Agency’s Gaia satellite, aiming to map stars in our galaxy in unprecedented detail, has come in to shed light on the issue.
The Gaia Archive opened on April 25, making public Gaia’s second data release to everyone. To quote the character Dave Bowman in the sci-fi classic 2001: A Space Odyssey: “It’s full of stars”. In fact, it contains data on the distances to more than 1.3 billion stars.
The Gaia satellite was launched in 2013 and has been scanning the sky with its two telescopes continuously ever since, with the aim of deciphering how our Milky Way galaxy formed and evolved. To do this, it is measuring something called parallax. If you hold a finger at arms length and look at it with one eye and then the other, your finger appears to shift position compared to the background. The angular change is called parallax.
Being in space allows Gaia to see similar tiny shifts in star positions. Observations at different locations six months apart (half way of its orbit around the Earth) are akin to looking at your finger with one eye and then the other. When you know the parallax as well as the distance from Gaia to the sun (or the distance from your nose to your eye), you can use simple trigonometry to work out the distance to each star (or your finger).
Stephen Hawking, in his own words
In memory of Stephen Hawking, who died on Wednesday at 76, the New York Times has gathered a selection of his quotes:
“Remember to look up at the stars and not down at your feet. Try to make sense of what you see and wonder about what makes the universe exist. Be curious. And however difficult life may seem, there is always something you can do and succeed at.”
Don’t miss the latest posts at Attention to the Unseen: Sign up for email updates.
First glimpses of the cosmic dawn
Near the beginning, not long after the Big Bang, the universe was a cold and dark place swirling with invisible gas, mostly hydrogen and helium. Over millions of years, gravity pulled some of this primordial gas into pockets. The pockets eventually became so dense they collapsed under their own weight and ignited, flooding the darkness with ultraviolet radiation. These were the very first stars in the universe, flashing into existence like popcorn kernels unfurling in the hot oil of an empty pan.
Everything flowed from this cosmic dawn. The first stars illuminated the universe, collapsed into the black holes that keep galaxies together, and produced the heavy elements that would make planets and moons and the human beings that evolved to gaze upon it all.
This epoch in our cosmic history has long fascinated scientists. They hoped that someday, using technology that was calibrated just right, they could detect faint signals from that moment. Now, they think they’ve done it.
Astronomers said Wednesday they have found, for the first time, evidence of the earliest stars. Using a table-sized radio instrument in the desert in Western Australia, the researchers detected radio emissions from the cold hydrogen that interacted with brand-new stars in that stage of the early universe.
Astronomers from Arizona State University, MIT, and the University of Colorado at Boulder, funded by the National Science Foundation, spent more than a decade trying to find this signal, calibrating and recalibrating the technology. Their results were published in Nature. [Continue reading…]
Don’t miss the latest posts at Attention to the Unseen: Sign up for email updates.