Once Again, Galaxies Look Surprisingly Mature Shortly After the Beginning of the Universe

A young galaxy with the catchy, roll-off-the-tongue name A1689-zD1 has experts in galactic formation talking. Recent observations show that this galaxy, seen as it would have looked just 700 million years after the Big Bang, is larger than initially believed, with significant outflows of hot gas from its core, and a halo of cold gas emanating from its outer rim. A1689-zD1 is considered representative of young ‘normal’ galaxies (as opposed to ‘massive’ galaxies), and the new observations suggest that the adolescence of normal galaxies may be more rambunctious than previous models suggest.

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If the First Black Holes Collapsed Directly, Could we Detect Radio Signals From Those Moments?

This artist’s impression shows a possible seed for the formation of a supermassive black hole. Credit: NASA/CXC/M. Weiss

The universe is littered with supermassive black holes. There’s one a mere 30,000 light-years away in the center of the Milky Way. Most galaxies have one, and some of them are more massive than a billion stars. We know that many supermassive black holes formed early in the universe. For example, the quasar TON 618 is powered by a 66 billion solar mass black hole. Since its light travels nearly 11 billion years to reach us, TON 618 was already huge when the universe was just a few billion years old. So how did these black holes grow so massive so quickly?

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Protogalaxy Cluster Found When the Cosmic Fog Was Starting to Clear, When the Universe Was Just 750 Million Years Old

Origin stories are a focus of many astronomical studies.  Planetary formation, solar system formation, and even galaxy formation have long been studied in order to understand how the universe came to be where it is today.  Now, a team of scientists from the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) consortium have found an extremely early “protogalaxy” that was formed approximately 750 million years after the big bang.  Studying it can provide insights into that early type of galaxy formation and everything that comes after.

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The galaxy with 99.99% dark matter isn’t so mysterious any more

Artist rendering of the dark matter halo surrounding our galaxy. Credit: ESO/L. Calçada

The dwarf galaxy known as Dragonfly 44 caused a stir recently: apparently it had way, way more dark matter than any other galaxy. Since this couldn’t be explained by our models of galaxy formation, it seemed like an oddball. But a new analysis reveals that Dragonfly 44 has much less dark matter than previously thought. In short: it’s totally normal.

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Elliptical Galaxy Messier 110 Has a Surprising Core of Hot Blue Stars

A new Hubble image of M 110 shows that these dwarf elliptical galaxies do contain some blue, hot young stars and that they may harbour areas of star formation after all. Image credit: ESA/Hubble & NASA, L. Ferrarese et al.

Messier 110 (NGC 205) is a satellite of the Andromeda Galaxy. It’s a dwarf elliptical galaxy, a common type of galaxy often found in galaxy clusters and groups, and it contains about 10 billion stars. Like all dwarf ellipticals, it doesn’t have the characteristic shape of galaxies like Andromeda or the Milky Way, with their vast, spiral arms. It has a smooth, featureless shape.

Dwarf ellipticals lack the blazing bright areas of active star formation that other galaxies display. In fact, astronomers think that they’re too old to have any young stars at all. But M110 appears to be different.

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Astronomers Uncover Dozens of Previously Unknown Ancient and Massive Galaxies

The ALMA array in Chile. Once ALMA was added to the Event Horizon Telescope, it increased the EHT's power by a factor of 10. Image: ALMA (ESO/NAOJ/NRAO), O. Dessibourg

For decades, astronomers have been trying to see as far as they can into the deep Universe. By observing the cosmos as it was shortly after the Big Bang, astrophysicists and cosmologists hope to learn all they can about the early formation of the Universe and its subsequent evolution. Thanks to instruments like the Hubble Space Telescope, astronomers have been able to see parts of the Universe that were previously inaccessible.

But even the venerable Hubble is incapable of seeing all that was taking place during the early Universe. However, using the combined power of some of the newest astronomical observatories from around the world, a team of international astronomers led by Tokyo University’s Institute of Astronomy observed 39 previously-undiscovered ancient galaxies, a find that could have major implications for astronomy and cosmology.

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What Will the James Webb Space Telescope See? A Whole Bunch of Dust, That’s What

With its helical appearance resembling a snail’s shell, this reflection nebula seems to spiral out from a luminous central star in this new NASA/ESA Hubble Space Telescope image. The star in the centre, known as V1331 Cyg and located in the dark cloud LDN 981 — or, more commonly, Lynds 981 — had previously been defined as a T Tauri star. A T Tauri is a young star — or Young Stellar Object — that is starting to contract to become a main sequence star similar to the Sun. What makes V1331Cyg special is the fact that we look almost exactly at one of its poles. Usually, the view of a young star is obscured by the dust from the circumstellar disc and the envelope that surround it. However, with V1331Cyg we are actually looking in the exact direction of a jet driven by the star that is clearing the dust and giving us this magnificent view. This view provides an almost undisturbed view of the star and its immediate surroundings allowing astronomers to study it in greater detail and look for features that might suggest the formation of a verylow-mass object in the outer circumstellar disc.

When it comes to the first galaxies, the James Webb Space Telescope will attempt to understand the formation of those galaxies and their link to the underlying dark matter. In case you didn’t know, most of the matter in our universe is invisible (a.k.a. “dark”), but its gravity binds everything together, including galaxies. So by studying galaxies – and especially their formation – we can get some hints as to how dark matter works. At least, that’s the hope. It turns out that astronomy is a little bit more complicated than that, and one of the major things we have to deal with when studying these distant galaxies is dust. A lot of dust.

That’s right: good old-fashioned dust. And thanks to some fancy simulations, we’re beginning to clear up the picture.

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The Milky Way is Actually Warped

Artist’s impression of the warped and twisted Milky Way disk. Credit: Chen Xiaodian/Kavli Institute of Astronomy and Astrophysics

For centuries, astronomers have been studying the Milky Way in order to get a better understanding of its size and structure. And while modern instruments have yielded invaluable observations of our galaxy and others (which have allowed astronomers to gain a general picture of what it looks like), a truly accurate model of our galaxy has been elusive.

For example, a recent study by a team of astronomers from National Astronomical Observatories of Chinese Academy of Sciences (NAOC) has shown that the large-scale structure of the Milky Way is quite warped. Based on their findings, it appears that this effect becomes increasingly evident the farther away one ventures from the core.

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We’re in the Milky Way’s Second Life. Star Formation was Shut Down for Billions of Years

Artist's impression of the spiral structure of the Milky Way with two major stellar arms and a bar. Credit: NASA/JPL-Caltech/ESO/R. Hurt

Since the birth of modern astronomy, scientists have sought to determine the full extent of the Milky Way galaxy and learn more about its structure, formation and evolution. According to current theories, it is widely believed that the Milky Way formed shortly after the Big Bang (roughly 13.51 billion years ago). This was the result of the first stars and star clusters coming together, as well as the accretion of gas directly from the Galactic halo.

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Globular Clusters Might not be as Old as Astronomers Thought. Like, Billions of Years Younger

A binary star system in a globular cluster. Credit: University of Warwick

Globular clusters have been a source of fascination ever since astronomers first observed them in the 17th century. These spherical collections of stars are among the oldest known stars in the Universe, and can be found in the outer regions of most galaxies. Because of their age and the fact that almost all larger galaxies appear to have them, their role in galactic evolution has remained something of a mystery.

Previously, astronomers were of the opinion that globular clusters were some of the earliest stars to have formed in the Universe, roughly 13 billion years ago. However, new research has indicated that these clusters may actually be about 4 billion years younger, being roughly 9 billion years old. These findings may alter our understanding of how the Milky Way and other galaxies formed, and how the Universe itself came to be.

The study, titled “Reevaluating Old Stellar Populations“, recently appeared online and is being evaluated for publication in The Monthly Notices for the Royal Astronomical Society. The study was led by Dr. Elizabeth Stanway, an Associate Professor in the Astronomy group at the University of Warwick, UK, and was assisted by Dr. J.J. Eldridge, a Senior Lecturer at the University of Auckland, New Zealand.

Within larger galaxies, like the Milky Way, globular clusters are part of the galactic halo. Between 150 and 180 are estimated to be part of the Milky Way alone. Credit: ESO

For the sake of their study, Dr. Stanway and Dr. Eldridge developed a series of new research models designed to reconsider the evolution of stars. These models, known as Binary Population and Spectral Synthesis (BPASS) models, had previously proven effective in exploring the properties of young stellar populations within the Milky Way and throughout the Universe.

Using these same models, Dr. Stanway and Dr. Eldridge studied a sample of globular clusters in the Milky Way and nearby quiescent galaxies. They also took into account the details of binary star evolution within globular clusters and used them to explore the colors of light and spectra from old binary populations. In short, binary star system evolution consists of one star expanding into a giant while the gravitational force of the smaller star strips away the atmosphere of the giant.

What they found was that these binary systems were about 9 billion years old. Since these stars are thought to have formed at the same time as the globular clusters themselves, this demonstrated that globular clusters are not as old as other models have suggested. As Dr. Stanway said of the BPASS models she and Dr. Eldridge developed:

“Determining ages for stars has always depended on comparing observations to the models which encapsulate our understanding of how stars form and evolve. That understanding has changed over time, and we have been increasingly aware of the effects of stellar multiplicity – the interactions between stars and their binary and tertiary companions.

An artist’s impression of a millisecond pulsar and its companion. The presence of binaries in globular clusters is a good means of providing age estimates of those clusters. Credit: ESA & Francesco Ferraro (Bologna Astronomical Observatory)

If correct, this study could open up new pathways of research into how massive galaxies and their stars are formed. However, Dr. Stanway admits that much work still lies ahead, which includes looking at nearby star systems where individual stars can be resolved – rather than considering the integrated light of a cluster. Nevertheless, the study could have immense significant for our understanding of how and when galaxies in our Universe formed.

“If true, it changes our picture of the early stages of galaxy evolution and where the stars that have ended up in today’s massive galaxies, such as the Milky Way, may have formed,” she said. “We aim to follow up this research in the future, exploring both improvements in modelling and the observable predictions which arise from them.”

An integral part of cosmology is understanding when the Universe came to be the way it is, not just how. By determining how old globular clusters are, astronomers will have another crucial piece of the puzzle as to how and when the earliest galaxies formed. And these, combined with observations that look to the earliest epochs of the Universe, could just yield a complete model of cosmology.

Further Reading: University of Warwick, arXiv