Hubble Reveals the Final Stages of a Dying Star

In April 2021 Hubble released its 31st-anniversary image. It’s a portrait of AG Carinae, one of the most luminous stars in the entire Milky Way. AG Carinae is in a reckless struggle with itself, periodically ejecting matter until it reaches stability sometime in the future.

Thanks to the Hubble, we get to watch the brilliant struggle.

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Astronomers Discover an Intermediate-Mass Black Hole as it Destroys a Star

Supermassive black holes (SMBH) reside in the center of galaxies like the Milky Way. They are mind-bogglingly massive, ranging from 1 million to 10 billion solar masses. Their smaller brethren, intermediate-mass black holes (IMBH), ranging between 100 and 100,000 solar masses, are harder to find.

Astronomers have spotted an intermediate-mass black hole destroying a star that got too close. They’ve learned a lot from their observations and hope to find even more of these black holes. Observing more of them may lead to understanding how SMBHs got so massive.

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Betelgeuse's Mysterious Dimming Solved. It was… Dust

At the beginning of 2020, the red giant star Betelgeuse started to dim significantly. Betelgeuse has been known to vary in brightness, but this one was unusual. It grew much dimmer than usual, and for a longer period. Since Betelgeuse is a star at the end of its life, it led some to speculate that perhaps it would go supernova. Astronomers didn’t think that was likely, and of course, Betelgeuse didn’t explode, and gradually its usual brightness returned. But astronomers were puzzled as to why Betelgeuse grew so dim.

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Massive Stars Mix Hydrogen in Their Cores, Causing Them to Pulse Every few Hours or Days

Main sequence stars fuse hydrogen in their cores. It’s how they produce the energy they need to shine and keeps them from collapsing under their own weight. As hydrogen is fused into helium, there is less hydrogen available in the core. This can pose a challenge for large stars. They need to fuse a tremendous amount of hydrogen to keep shining, and they can’t do that when core hydrogen is depleted. Fortunately, they can solve this problem by mixing more hydrogen into their core. A new study in Nature Astronomy shows us how this mixing happens.

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Newly Forming Stars Don’t Blast Away Material as Previously Believed. So Why Do They Stop Growing?

We thought we understood how stars are formed. It turns out, we don’t. Not completely, anyway. A new study, recently conducted using data from the Hubble Space Telescope, is sending astronomers back to the drawing board to rewrite the accepted model of stellar formation.

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VY Canis Majoris is “Like Betelgeuse on Steroids”

The disappearance of a star can take many forms.  It could go supernova.  It could turn into a black hole.  Or it could just fade away quietly.  Sometimes, the last of these is actually the most interesting to observe.  That is the case for one of the largest stars ever found – VY Canis Majoris, a red supergiant approximately 3840 light years away in the Canis Major constellation.  

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A New Study Says That Betelgeuse Won’t Be Exploding Any Time Soon

I have stood under Orion The Hunter on clear evenings willing its star Betelgeuse to explode. “C’mon, blow up!” In late 2019, Betelgeuse experienced an unprecedented dimming event dropping 1.6 magnitude to 1/3 its max brightness. Astronomers wondered – was this dimming precursor to supernova? How cosmically wonderful it would be to witness the moment Betelgeuse explodes. The star ripping apart in a blaze of light scattering the seeds of planets, moons, and possibly life throughout the Universe. Creative cataclysm.

Only about ten supernova have been seen with the naked eye in all recorded history. Now we can revisit ancient astronomical records with telescopes to discover supernova remnants like the brilliant SN 1006 (witnessed in 1006AD) whose explosion created one of the brightest objects ever seen in the sky. Unfortunately, latest research suggests we all might be waiting another 100,000 years for Betelgeuse to pop. However, studying this recent dimming event gleaned new information about Betelgeuse which may help us better understand stars in a pre-supernova state.

This comparison image shows Betelgeuse, before and after its unprecedented dimming
ESO / M. Montargès et al.
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This is a Simulation of the Interstellar Medium Flowing Like Smoke Throughout the Milky Way

How do stars form?

We know they form from massive structures called molecular clouds, which themselves form from the Interstellar Medium (ISM). But how and why do certain types of stars form? Why, in some situations, does a star like our Sun form, versus a red dwarf or a blue giant?

That’s one of the central questions in astronomy. It’s also a very complex one.

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Astronomers Discover Hundreds of High-Velocity Stars, Many on Their Way Out of the Milky Way

Within our galaxy, there are thousands of stars that orbit the center of the Milky Way at high velocities. On occasion, some of them pick up so much speed that they break free of our galaxy and become intergalactic objects. Because of the extreme dynamical and astrophysical processes involved, astronomers are most interested in studying these stars – especially those that are able to achieve escape velocity and leave our galaxy.

However, an international team of astronomers led from the National Astronomical Observatories of China (NAOC) recently announced the discovery of 591 high-velocity stars. Based on data provided by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and the ESA’s Gaia Observatory, they indicated that 43 of these stars are fast enough to escape the Milky Way someday.

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