Hubble Catches New Stars, Individually, Forming In Galaxies Beyond The Milky Way
“There are a massive variety of star-forming regions nearby, and Hubble’s new Legacy ExtraGalactic UV Survey (LEGUS) is now the sharpest, most comprehensive one ever.
By imaging 50 nearby, star-forming spiral and dwarf galaxies, astronomers can see how the galactic environment affects star-formation.”
Within galaxies, new stars are going to be formed from the existing population of gas. But how that gas collapses and forms stars, as well as the types, numbers, and locations of the stars that will arise, is highly dependent on the galactic environment into which they are born. Dwarf galaxies, for example, tend to form stars when a nearby gravitational interaction triggers them. These bursts occur periodically, leading to multiple populations of stars of different ages. Spirals, on the other hand, form their new stars mostly along the lines traced by their arms, where the dust and gas is densest. Thanks to the Hubble Space Telescope, we’re capable of finding these stars and resolving them individually, using a combination of optical and ultraviolet data.
The best part? These are individually resolved stars from well outside our own galaxy: in 50 independent ones. Here’s what Hubble’s new LEGUS survey is revealing.
When Will We Break The Record For Most Distant Galaxy Ever Discovered?
“Finally, beyond a certain distance, the Universe hasn’t formed enough stars to reionize space and make it 100% transparent.
We only perceive galaxies in a few serendipitous directions, where copious star-formation occurred.
In 2016, we fortuitously discovered GN-z11 at a redshift of 11.1: from 13.4 billion years ago.
But recent, indirect evidence suggests stars formed at even greater redshifts and earlier times.“
It was only a couple of years ago that we set the current record for where the most distant galaxy is: from 13.4 billion years ago, when the Universe was just 3% its current age. This record is unlikely to be broken with our current set of observatories, as discovering a galaxy this distant required a whole bunch of unlikely, serendipitous phenomena to line up at once. But in 2020, the James Webb Space Telescope will launch: an observatory optimized for finding exactly the kinds of galaxy that push past the limits of what Hubble can do. We fully expect to not only break the record for most distant galaxy ever discovered, but to learn, for the first time, exactly where and when the first galaxies in the Universe truly formed.
Until then, it’s lots of fun to speculate as to when and where they might be, but it will take the observations of a lifetime to smash this cosmic record!
Hubble’s Greatest Discoveries Weren’t Planned; They Were Surprises
“And if we head out beyond our own galaxy, that’s where Hubble truly shines, having taught us more about the Universe than we ever imagined was out there. One of the greatest, most ambitious projects ever undertaken came in the mid-1990s, when astronomers in charge of Hubble redefined staring into the unknown. It was possibly the bravest thing ever done with the Hubble Space Telescope: to find a patch of sky with absolutely nothing in it — no bright stars, no nebulae, and no known galaxies — and observe it. Not just for a few minutes, or an hour, or even for a day. But orbit-after-orbit, for a huge amount of time, staring off into the nothingness of empty space, recording image after image of pure darkness.
What came back was amazing. Beyond what we could see, there were thousands upon thousand of galaxies out there in the abyss of space, in a tiny region of sky.”
28 years ago today, the Hubble Space Telescope was deployed. Since that time, it’s changed our view of the Solar System, the stars, nebulae, galaxies, and the entire Universe. But here’s the kicker: almost all of what it discovered wasn’t what it was designed to look for. We were able to learn so much from Hubble because it broke through the next frontier, looking at the Universe in a way we’ve never looked at it before. Astronomers and astrophysicists found clever ways to exploit its capabilities, and the observatory itself was overbuilt to the point where, 28 years later, it’s still one of the most sought-after telescopes as far as observing time goes.
Hubble’s greatest discoveries weren’t planned, but the planning we did enabled them to become real. Here are some great reasons to celebrate its anniversary.
One Galaxy Cluster, Through Hubble’s Eyes, Can Show Us The Entire Universe
“There’s more gravity than the gas can provide, showing the presence of non-baryonic dark matter.
But all the mass, combined, contributes to gravitational lensing.
The bending of space stretches and magnifies the light from galaxies behind the cluster.
This is the whole purpose of the joint Hubble/Spitzer RELICS program, highlighted by this galaxy cluster.”
Want to see the most distant galaxy in the Universe? You don’t simply need the world’s greatest telescopes; you also need an assist from gravity. Galaxy clusters provide the largest gravitational sources in the Universe, thereby providing the largest natural magnification enhancements through gravitational lensing. While the internal dynamics of the galaxies tell us that there must be dark matter present, and that dark matter is something other than normal (atom-based) matter, the overall gravitational effects enhance any telescope-based views of the Universe. The joint Hubble/Spitzer RELICS program is imaging 41 of these massive galaxy clusters, hoping to magnify ultra-distant galaxies more distant than any we’ve ever seen before. When the James Webb Space Telescope comes online, these will be the places where our greatest target candidates for “most distant galaxy in the Universe” will come from.
The next step of our great cosmic journey is beginning right now. Come get a glimpse of the future for yourself!
This Is How The Milky Way Is Eating Our Galactic Neighbors
“New star formation is triggered by mutual gravitational interactions combined with the Milky Way’s tug.
The gas within these galaxies gets shunted into new clusters, including the local group’s largest star-forming region: 30 Doradus.
But these gravitational interactions also strip the gas away from these dwarfs, where the Milky Way will devour it.
The largest gas stream seems to connect both galaxies, but which cloud it originated from was a mystery.
Until, that is, scientists led by Andrew Fox looked at the absorption effects of this gas from background quasar light.”
While the visible Universe extends for tens of billions of light years, our local group of galaxies extends for only a few million. Around our own Milky Way are a handful of dwarf galaxies, including two bright ones: the Large and Small Magellanic Clouds. These two galaxies contain large numbers of young stars, show evidence of hot, glowing gas, and are destined to be devoured by our Milky Way in cosmically short order. But until that happens, they’re engaged in a cosmic tug-of-war with one another, battling to expel the gas from each other and capture it for themselves. Because the Milky Way is nearby, the expelled gas is getting stretched and drawn into our own galaxy, but which cloud, the Large or the Small, did it arise from?
Owing to new work by a Hubble team led by Andrew Fox, we finally know it’s the Small Magellanic Cloud. Here’s how, and here’s what it means for science.
Earliest Evidence For Stars Smashes Hubble’s Record And Points To Dark Matter
“And most importantly, this is a glimpse into what it’s like to push back the frontiers of science. The first evidence for anything new is almost always indirect, weak, and difficult to interpret. But these unexplained signals have the power to explain what we don’t yet fully understand: how the Universe came to be the way it is today. For the first time, the Universe has given us an observational clue of where and when and what to look for. It’s up to us to take the next step.”
Earlier today, a new study was released in Nature, showcasing the earliest evidence of stars in cosmic history. The previous record was held by Hubble, which had spotted a galaxy from when the Universe was just 400 million years old: 3% of its current age. Now, indirect measurements of starlight, through the technique of radio astronomy looking for a particular hydrogen transition, has shown us evidence for a tremendous population of stars from when the Universe was between 180 and 260 million years old. This could be, truly, the first stars and galaxies of all, and it’s occurring in exactly the range that the James Webb Space Telescope will be sensitive to. Moreover, the gas that we’re observing shows signs of being far cooler than we’ve anticipated, meaning that something strange is going on, and one leading candidate is that dark matter is interacting with and cooling the gas!
This is the earliest evidence for stars in the entire Universe, and it’s just smashed Hubble’s previous record. Come get the full story right now!
World’s Largest Telescope To Finally See Stars Without Artificial Spikes
“Compared to what we can presently see with the world’s greatest observatories, the next generation of ground-based telescopes will open up a slew of new frontiers that will peel back the veil of mystery that enshrouds the unseen Universe. In addition to planets, stars, gas, plasma, black holes, galaxies, and nebulae, we’ll be looking for objects and phenomena that we’ve never seen before. Until we look, we have no way of knowing exactly what wonders the Universe has waiting for us. Owing to the clever and innovative design of the Giant Magellan Telescope, however, the objects we’ve missed due to diffraction spikes of bright, nearby stars will suddenly be revealed. There’s a whole new Universe to be observed, and this one, unique telescope will reveal what no one else can see.”
When we take images of the Universe, we are so used to seeing the sight of spikes around the stars in our own galaxy, it frequently doesn’t even occur to us that stars are near-perfect spheres, without any spikes to them at all. These are simply image artifacts created by reflecting telescopes, since they require a secondary mirror to collect and focus the light that the primary mirror reflects. These secondary mirrors are held in place by “spider arms,” which cross the plane of the mirror and block some of the light, creating these diffraction spikes. Up until now, these spikes were unavoidable, and the best we could do was using imaging techniques to try and subtract them out. But due to a brilliant design feature, the upcoming Giant Magellan Telescope, due to be the world’s largest (for a time) at 25 meters, will be the first giant reflector to image the stars exactly as they are: without these spikes at all.
It’s an observational feat that could not only revolutionize astronomy and telescope design, but will allow us to observe faint objects near bright stars, unfettered, for the very first time.
The Pillars Of Creation Haven’t Been Destroyed, After All
“Moreover, the best evidence for changes comes at the base of the pillars, indicating an evaporation time on the order of between 100,000 and 1,000,000 years. The idea that the pillars have already been destroyed has been demonstrated not to be true. It’s one of the great hopes of science that any controversial claims will be laid to rest by more and better data, and this is one situation where that has paid off in spades. Not only has there not been a supernova that’s in the process of destroying the pillars, but the pillars themselves should be robust for a long time to come.”
In 1995, NASA’s Hubble Space Telescope observed the Eagle Nebula, identifying the now-iconic pillars of creation, where newborn stars are forming inside a gas-rich, dusty region of space. Outside of those pillars, thousands of stars shine brightly, working to boil the gas off, while inside, the radiation from newly-formed stars works to boil it away from the inside. In 2007, the Spitzer Space Telescope, observing in the infrared, suggested that these pillars were blown apart thousands of years ago by a supernova, and that the light hadn’t simply reached our eyes yet. This was controversial, however, and follow-up observations would be required to know for certain. Well, the data has come in, and guess what?
The pillars of creation haven’t been destroyed after all, as the supernova seems to never have occurred. Instead of ~1,000 years, we should have hundreds of thousands of years before the pillars disappear completely. Come get the full story.
How The James Webb Space Telescope Will Deploy (In An Ideal World)
“Once the launch vehicle reaches a distance of 10,000 kilometers from Earth, just a half hour into its journey, the telescope separates from the upper stage of the rocket. At this point, JWST is free from the launch vehicle, and is now on its own, on its way to its ultimate destination. Two minutes later, the first key, but difficult step must succeed: to deploy its solar array. James Webb has a battery on board, but will only need it until the array is deployed. The thrusters will then fire, pointing the solar panels towards the Sun and orienting the observatory properly for the next step. If the array fails, the battery will last only a few hours. This step, like a great many, is a single-point-of-failure for the entire mission.”
The James Webb Space Telescope is optimized for uncovering so many secrets of the Universe, it’s impossible to list them all in a single article. From the first stars and galaxies to atmospheres around Earth-sized worlds, from the molecules present in newly-forming planets to direct images of Jupiter-sized worlds in distant solar systems, and from the pristine material left over from the Big Bang to finding the majority of water in the Universe, James Webb will answer questions that no observatory has ever addressed before. But only if it successfully launches and deploys! This takes a tremendous amount of work from vastly separate teams, all coming together without a single failure. Yet the plans have been vetted and tested as thoroughly as possible from the ground, and once the final preparatory steps are taken later this year, all that remains will be to execute the plan.
What has to happen in order for James Webb to successfully launch, deploy, and get onto the science? Find out, in-depth, today!
New Dark Matter Physics Could Solve The Expanding Universe Controversy
“If either photons, neutrinos, or some new type of dark radiation (that interacts with dark matter but not any of the normal particles) has a non-zero cross-section with dark matter, it could bias measurements of the Hubble rate to an artificially low value, but only for one type of measurement: the kind that you get from measuring these leftover relics. If interactions between dark matter and radiation are real, they might not only explain this cosmic controversy, but could be our first hint of how dark matter might directly interact with other particles. If we’re lucky, it could even give us a clue to how to finally see dark matter directly.”
One of the biggest controversies in physics today is over the expanding Universe. Despite attempts to measure the Hubble rate for nearly 100 years, we still don’t know exactly how fast the Universe expands. Two independent classes of methods, from the cosmic distance ladder and the Big Bang’s leftover relic, give two very precise and incompatible results: 73 km/s/Mpc and 67 km/s/Mpc, respectively. There’s always the possibility that one class of methods gives a biased answer, and we simply haven’t uncovered the bias. But it’s also possible that new physics is responsible, that both teams are right, and that the discrepancy is a hint of the next great leap forward in our understanding of the fundamental properties of the Universe itself.
One exciting possibility is that dark matter has a new interaction with radiation: either photons, neutrinos, or a new type of ‘dark radiation.’ Come learn more about it today!