Nearby Supernovae Exploded Just a few Million Years Ago, Leading to a Wave of Star Formation Around the Sun

Artist's illustration of the Local Bubble with star formation occurring on the bubble's surface. Scientists have now shown how a chain of events beginning 14 million years ago with a set of powerful supernovae led to the creation of the vast bubble, responsible for the formation of all young stars within 500 light years of the Sun and Earth. Credit: Leah Hustak (STScI)

The Sun isn’t the only star in this galactic neighbourhood. Other stars also call this neighbourhood home. But what’s the neighbourhood’s history? What triggered the birth of all those stars?

A team of astronomers say they’ve pieced the history together and identified the trigger: a series of supernovae explosions that began about 14 million years ago.

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New Hubble Image Shows Dark Cocoons Where New Stars are Forming

This image shows knots of cold, dense interstellar gas where new stars are forming. These Free-floating Evaporating Gaseous Globules (frEGGs) were first seen in Hubble’s famous 1995 image of the Eagle Nebula. Because these lumps of gas are dark, they are rarely seen by telescopes. Image Credit: NASA, ESA, and R. Sahai (Jet Propulsion Laboratory); Processing: Gladys Kober (NASA/Catholic University of America)

Star formation is a complex process. But in simple terms, a star forms due to clumps and instabilities in a cloud of molecular hydrogen called a Giant Molecular Cloud (GMC). As more and more gas accumulates and collapses inward, the pressure becomes immense, the gas eventually heats up to millions of degrees, and fusion begins.

But what happens to the gas that remains as the young star forms? Some of it can form a type of dark halo called a frEGG—a free-floating Evaporating Gaseous Globule. And, proving that the Universe is indeed strange, the frEGG itself can contain another stellar embryo. The frEGG can be quite opaque, making it difficult to observe the star’s formation process in all its complexity.

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Are the Burned-Out Remnants of the First Stars all Around us?

An artist's illustration of the Universe's first stars, called Population 3 stars. Pop 3 stars would have been much more massive than most stars today, and would have burned hot and blue. Their lifetimes would've been much shorter than stars like our Sun. Image Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=1582286

The first stars to appear in the universe lived fast and died young. Today, none of them likely remain. But their remnants, the black holes and neutron stars, might still wander around the cosmos. Unfortunately, they’re extremely difficult to detect unless they merge, and according to new research the only way to see them would be to conduct an unprecedented survey of the local volume of the universe.

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Astronomers Find a Giant Cavity in Space, Hollowed out by an Ancient Supernova

A cavity of empty space was likely caused by a supernova. Credit: Alyssa Goodman/Center for Astrophysics | Harvard & Smithsonian

Star formation is a topic astronomers are still trying to fully understand. We know, for example, that stars don’t form individually, but rather are born within vast interstellar molecular clouds. These stellar nurseries contain gas dense enough for gravity to trigger the formation of stars. In spiral galaxies, these molecular clouds are most commonly found within spiral arms, which is why stars are most often born in spiral arms.

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The Galactic Beauty of Star Formation

Image of Galaxy NGC 3627 located in the constellation LEO. The golden gas glow corresponds to clouds of ionized hydrogen, while the bluish regions reveal the distribution of slightly older stars. Credit: ESO/PHANGS

I’d never seen galaxy images like this before. Nobody had! These images highlight star forming regions in nearby(ish) galaxies. There are still a number of unanswered questions surrounding how star formation actually occurs. To answer those questions, we are observing galaxies that are actively forming stars within giant clouds of gas. Until recently, we didn’t have the resolution needed to clearly image the individual gas clouds themselves. But images released by a project called PHANGS (Physics at High Angular resolution in Nearby GalaxieS) in a collaboration between the European Southern Observatory Very Large Telescope and the Atacama Large millimeter/submillmeter Array (ALMA) have provided never before seen detail of star forming clouds in other galaxies.

This image combines observations of the nearby galaxies NGC 1300, NGC 1087, NGC 3627 (top, from left to right), NGC 4254 and NGC 4303 (bottom, from left to right) taken with the Multi-Unit Spectroscopic Explorer (MUSE) on ESO’s Very Large Telescope (VLT). Each individual image is a combination of observations conducted at different wavelengths of light to map stellar populations and warm gas.. Image and Image Description PHANGS/ESO. Original Image
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One of the Brightest Star-Forming Regions in the Milky Way, Seen in Infrared

Certain parts of the galaxy are more magical than others.  There are barren wastelands where barely a particle strays through occasionally, and there are fantastical nebulae that can literally light up the sky.  But beyond their good looks, those nebulae hold secrets to understanding some of the most important features of any galaxy – stars. Now, for the first time, a team from the University of Maryland managed to capture a high resolution image of one of the most active star-forming regions in our part of the galaxy.  Data from that image are not only spectacular, but can illuminate the details of the star formation process.

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Star Formation Begins When Clouds of Gas Crash Into Each Other

another seyfert galaxy
The NASA/ESA Hubble Space Telescope has captured this vivid image of spiral galaxy Messier 77 — a galaxy in the constellation of Cetus, some 45 million light-years away from us. The streaks of red and blue in the image highlight pockets of star formation along the pinwheeling arms, with dark dust lanes stretching across the galaxy’s starry centre. The galaxy belongs to a class of galaxies known as Seyfert galaxies, which have highly ionised gas surrounding an intensely active centre.

To trigger star formation, you need to compress a lot of gas into not a lot of volume. To make a lot of stars at once, you need to really pack it in. Until now, astronomers haven’t been sure how to pull this off. But a collection of 20 papers outlines how to do it: make giant clouds of gas crash into each other.

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Young Stars can Evaporate Nearby Disks Before They can Form Planets

Artist's conceptualization of the dusty TYC 8241 2652 system as it might have appeared several years ago when it was emitting large amounts of excess infrared radiation. Credit: Gemini Observatory/AURA artwork by Lynette Cook. https://www.gemini.edu/node/11836

Many planetary systems may get snuffed out before they even get a chance to form, according to new research. The culprit: nearby stars, capable of evaporating entire protoplanetary disks just when they begin to form.

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