Podcaster: Richard Drumm
Title: UNAWE Space Scoop – Watch out, Earth! A Dying Star Just Ate A Planet
Organization: 365 Days Of Astronomy
Link : http://365daysofastronomy.org/ ; https://spacescoop.org/en/scoops/2311/fast-and-furious-starring-dual-quasars/
Description: Space scoop, news for children.
For the first time astronomers found direct clues of a dying sun-like star eating an exoplanet. The star is in the constellation Aquila, the Eagle, and is called ZTF SLRN-2020, but for now let’s just call it 2020. So much easier to remember!
Using the NSF NOIRLab’s Gemini South Telescope in Chile, researchers observed a long burst of light coming from the star, a burst low in energy. This is a telltale sign of a planet skimming along near the star’s surface. This ‘long & low’ stellar outburst took place in our Milky Way nearly 13,000 light-years away from Earth.
Such events are estimated to occur at most only a few times each year and maybe only once a decade, across the entire Milky Way galaxy. So should planets like Mercury, Venus and Earth be worried?
Let’s find out!
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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Transcript:
This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
Today’s story is…
Watch out, Earth! A Dying Star Just Ate A Planet
For the first time astronomers found direct clues of a dying sun-like star eating an exoplanet.
The star is in the constellation Aquila, the Eagle, and is called ZTF SLRN-2020, but for now let’s just call it 2020.
So much easier to remember!
Using the NSF NOIRLab’s Gemini South Telescope in Chile, researchers observed a long burst of light coming from the star, a burst low in energy.
This is a telltale sign of a planet skimming along near the star’s surface.
This ‘long & low’ stellar outburst took place in our Milky Way nearly 13,000 light-years away from Earth.
Such events are estimated to occur at most only a few times each year and maybe only once a decade, across the entire Milky Way galaxy.
So should planets like Mercury, Venus and Earth be worried?
Let’s find out!
Stars like our Sun fuse Hydrogen atoms in their cores to form Helium, in a process called nuclear fusion.
This internal process literally holds the star up and allows the star to not be crushed by the weight of its outermost layers.
When its core runs out of Hydrogen, the fusion reaction begins to shift to the star’s outer layers, and the increased heat that’s generated causes the layers to expand and grow bigger.
The Helium in the core now begins to fuse, turning into Carbon, the core gets much hotter than before, and the star eventually grows into a red giant.
The increased heat from the core literally pushes the outer parts of the star away.
Think of the gravity well of the star as being like the flare of a trumpet’s horn.
As the star swells up, the outer parts are basically pushed up out of the gravity well.
Ultimately all that’s left is the core of the star, which we then call a white dwarf.
In about 5 billion years, our Sun will become a red giant!
Our parent star will grow so big as it dies, that it will eat up the inner planets of our Solar System.
Possibly even including Earth!
The law of conservation of angular momentum will have Earth slowly move farther away from the Sun as the Sun’s density profile changes.
The unknown bit is whether Earth’ll move far enough away to not get consumed.
Either way, it’ll be fried to a cinder!
Such dramatic star vs. planet interactions produce a huge outburst of energy and matter, causing planets to slip from their orbit when they encounter the resistance that comes from being in the star’s atmosphere!
This is like turning on retro-rockets, slowing down the planet, that then falls into the star.
The entry of the planet into the star gives the star a boost of new energy, causing it to brighten dramatically!
With this event that happened with star 2020, astronomers have captured just such an event!
It’s quite challenging to tell apart a planet-gulping event, like 2020, from the more common solar flares or coronal-mass ejections.
They can look a lot alike.
Thanks to the Gemini South Adaptive Optics Imager, or GSAOI, on the Gemini South telescope, the astronomers received essential data by which they could confirm that their real-time observations were indeed that of a ‘planetary-engulfment’.
With these results in hand, astronomers can now use improved techniques to look for similar events elsewhere in the cosmos.
This will help find the missing link in understanding what really happens during the final stages of planetary systems like our own.
Hey, here’s a cool fact!
The ‘long and low’ stellar fireworks lasted for 250 days.
Astronomers calculated that the ejected material from the burst is made of hydrogen that has 33 Earth masses – and dust that has one third Earth mass.
The team also estimated that the star in this event has 1 to 1 1/2 times the mass of our Sun and the planet it ate could have had 1 to 10 times the mass of Jupiter!
Our Sun will do this red giant business in about 5 billion years, so don’t worry yourself too much about it.
We’ve got time to make our plans.
We’ll just have to move to Mars, and then Jupiter’s moons to live.
No biggie!
Thank you for listening to the 365 Days of Astronomy Podcast!
365 Days of Astronomy
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