This is the Smiling Cat Nebula, aka Sh2-284. It's a stellar nursery of ionized hydrogen, powered by young stars in the center. If you can't see the cat, maybe you're more of a dog person. Image Credit: ESO/VPHAS+ team. Acknowledgement: CASU
A stellar nursery sounds like a placid place where baby stars go about their business undisturbed. But, of course, a stellar nursery is nothing like that. (Babies are noisy and cry a lot.) They’re dynamic places where powerful elemental forces rage mightily and bend the surroundings to their will. And this one, even though its name is the drowsy-sounding Smiling Cat Nebula, is no exception.
Artist's impression of the Milky Way Galaxy. Credit: ESO
Beginning in 1610, when famed Renaissance polymath Galileo Galilei observed the night sky using a telescope of his own manufacture, astronomers gradually realized that our Solar System is part of a vast collection of stars known today as the Milky Way Galaxy. By the 20th century, astronomers had a good idea of its size and structure, which consisted of a central “bulge” surrounded by an extended disk with spiral arms. Despite all we’ve learned, determining the true morphology of the Milky Way has remained a challenge for astronomers.
Since we, the observers, are embedded in the Milky Way’s disk, we cannot see through the center and observe what’s on the other side. Using various methods, though, astronomers are getting closer to recreating what a “birds-eye” view of the galaxy would look like. For instance, a team of researchers from the Chinese Academy of Sciences (CAS) used the precise locations of very young objects in our galaxy (for the first time) to measure the morphology of the Milky Way. This revealed a multiple-arm morphology consisting of two symmetrical arms in the inner region and many irregular ones in the outer region.
Massive planets can form around low-mass stars, but they're rare. Image Credit: NASA
Can low-mass stars play host to giant, Jupiter-sized planets? Theories of planet formation suggest that it’s highly unlikely. But a team of scientists in the UK found that it’s possible, though rare.
Image of the Carina Nebula (NGC 3324) captured by Webb’s Near-Infrared Camera (NIRCam), Credit: NASA/ESA/CSA/STScI
The powerful James Webb Space Telescope is a mighty technological tool. Astrophysicists first conceived it over 20 years ago, and after many twists and turns, it was launched on December 2st, 2021. Now it’s in a halo orbit at the Sun-Earth L2 point, where it will hopefully continue operating for 20 years.
It’s only been a few months since its first images were released, and it’s already making progress in answering some of the Universe’s most compelling questions. In a newly-released image, the JWST peered deep inside massive clouds of gas and dust to watch young stars come to life in their stellar cocoons.
The young star IRS 63 has baby planets forming around it while the star itself is still forming. Image Credit: Segura-Cox et al, 2020.
It looks like we may have to update our theories on how stars and planets form in new solar systems. A team of astronomers has discovered young planets forming in a solar system that’s only about 500,000 years old. Prior to this discovery, astronomers thought that stars are well into their adult life of fusion before planets formed from left over material in the circumstellar disk.
Now, according to a new study, it looks like planets and stars can form and grow up together.
This figure shows the dust rings around young stars captured by the Gemini Planet Imager Exoplanet Survey, or GPIES. The rings show a diversity of shapes and sizes, made more extreme by the different projections of the rings on the sky. (UC Berkeley image by Thomas Esposito)
Over the next decade, several very powerful telescopes will come online. Observing time on these ‘scopes will be in high demand, and their range of targets will span a whole host of topics in astronomy, astrophysics, and cosomology.
One of the topics near the top of the list is exoplanets.
But how will astronomers know where to spend their precious exoplanet observing time?
The fifteen images of protoplanetary disks, captured with ESO's Very Large Telescope Interferometer. CREDIT
Jacques Kluska et al.
Astronomy is advancing to the point where we can see planets forming around young stars. This was an unthinkable development only a few years ago. In fact, it was only two years ago that astronomers captured the first image of a newly-forming planet.
Now there are more and more studies into how planets form, including a new one with fifteen images of planet-forming disks around young stars.
Are baby planets responsible for the gaps and rings we’ve spotted in the disks that surround distant, young stars? Image Credit: C. Pinte et al, 2020
Astronomers like observing distant young stars as they form. Stars are born out of a molecular cloud, and once enough of the matter in that cloud clumps together, fusion ignites and a star begins its life. The leftover material from the formation of the star is called a circumstellar disk.
As the material in the circumstellar disk swirls around the now-rotating star, it clumps up into individual planets. As planets form in it, they leave gaps in that disk. Or so we think.
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.
The million-year-old star HL Tau and its protoplanetary disk. Image: Carrasco-Gonzalez et. al.; Bill Saxton, NRAO/AUI/NSF
The currently accepted theory of planet formation goes like this: clouds of gas and dust are compressed or begin to draw together. When enough material clumps together, a star is formed and begins fusion. As the star, and its cloud of gas and dust rotate, other clumps of matter coagulate within the cloud, eventually forming planets. Voila, solar system.
There’s lots of evidence to support this, but getting a good look at the early stages of planetary formation has been difficult.
But now, an international team of astronomers using the Karl G. Jansky Very Large Array (VLA) have captured the earliest image yet of the process of planetary formation. “We believe this clump of dust represents the earliest stage in the formation of protoplanets, and this is the first time we’ve seen that stage,” said Thomas Henning, of the Max Planck Institute for Astronomy (MPIA).
This story actually started back in 2014, when astronomers studied the star HL Tau and its dusty disk with the Atacama Large Millimetre/sub-millimetre Array (ALMA.) That image, which showed gaps in HL Tau’s proto-planetary disk caused by proto-planets sweeping up dust in their orbits, was at the time the earliest image we had of planet formation. HL Tau is only about a million years old, so planet formation in HL Tau’s system was in its early days.
Now, astronomers have studied the same star, and its disk, with the VLA. The capabilities of the VLA allowed them do get an even better look at HL Tau and its disk, in particular the denser area closest to the star. What VLA revealed was a distinct clump of dust in the innermost region of the disk that contains between 3 to 8 times the mass of the Earth. That’s enough to form a few terrestrial planets of the type that inhabit our inner Solar System.
On the left is the ALMA image of HL Tau. On the right is the VLA image showing the clump of dust near the star. Image: Carrasco-Gonzalez et al,; Bill Saxton, NRAO/AUI/NSF
“This is an important discovery, because we have not yet been able to observe most stages in the process of planet formation,” said Carlos Carrasco-Gonzalez from the Institute of Radio Astronomy and Astrophysics (IRyA) of the National Autonomous University of Mexico (UNAM).
Of course the star in question, HL Tau, is interesting as well. But the formation and evolution of stars is much more easily studied. It’s our theory of planet formation which needed some observational confirmation. “This is quite different from the case of star formation, where, in different objects, we have seen stars in different stages of their life cycle. With planets, we haven’t been so fortunate, so getting a look at this very early stage in planet formation is extremely valuable,” said Carrasco-Gonzalez.
