Why scientists are stoked about mysterious black hole stars

You've heard of black holes. You've heard of stars. But have you heard of the newly discovered black hole stars that may explain multiple mysteries of the universe? We just did and we're honestly freaking out about it. Learn everything you need to know about it in this episode. Plus, hear some other cool stories fresh off the presses: Which exercise can help reduce your risk of dementia and how shrews shrink — and then regrow — parts of their body throughout the year. Interested in hearing more reporting on space, scientific mysteries or other emerging science? We want to know! Email us what you'd like us to talk about at [email protected] mailto:[email protected]! Support public media with NPR+ and enjoy perks for over 25 podcasts like this one. This show’s perks include sponsor-free listening. Learn more at plus.npr.org http://plus.npr.org/. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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  Hey, Regina Barber here to ask if you're following Short Wave on the NPR app or whichever one you're using. It's a little action that goes a long way for our small team. OK, here's the show.

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  You're listening to Short Wave from NPR.

• 0:34Speaker 02

  Short wavers, Nate Rot here with my co-host Gina B.

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  Hey, Nate.

• 0:39Speaker 02

  We are back with our bi-weekly science news roundup with friend of the pod and host of All Things Considered, Elsa Chang.

• 0:46Speaker 01

  Are we really a friend?

• 0:48Speaker 02

  Oh, Elsa, you're family. OK, so our first topic is in Gina's wheelhouse, Elsa.

• 0:54Speaker 01

  Hmm.

• 0:55Speaker 02

  Space.

• 0:56Speaker 01

  Oh, of course.

• 0:56Speaker 03

  The whole universe is my wheelhouse.

• 0:58Speaker 02

  Yeah.

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  And it's a wild mystery that we're going to be talking about that's being described as a brand new object, a black hole star.

• 1:08Speaker 01

  A black hole star? I don't even know what that is.

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  Well, Elsa, to warm up for this discussion about the regular black holes of our universe, we are going to quiz you.

• 1:18Speaker 01

  Oh, my God, no, I'm already nervous.

• 1:20Speaker 02

  It's happening. On some black hole facts that Short Wave has covered in the past. So there's no excuses for you here.

• 1:26Speaker 01

  Oh, my God, I haven't committed everything that comes out of your mouth to my memory?

• 1:30Speaker 02

  Lock in. OK, first question.

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  Uh huh.

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  Black holes are not actually holes at all. What shape are they?

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  Triangle.

• 1:42Speaker 03

  Sadly, no, that's not correct. Black holes are spheres that are kind of squished. It's like three dimensional.

• 1:50Speaker 01

  They're spheres? I'd like to know if sphere is one syllable or two syllables. That's my conundrum.

• 1:55Speaker 03

  Spheres.

• 1:56Speaker 02

  I don't have an answer to that either. Second question.

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  Yeah.

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  If you were to fall into a black hole, Elsa, depending on the black hole, your body could be stretched like a noodle?

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  Ow.

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  Scientists have a name for when that happens. What is it?

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  Making pasta?

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  The clue is like a noodle.

• 2:20Speaker 03

  What?

• 2:21Speaker 01

  It's like a noodle.

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  Hold her hand.

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  Canoodling?

• 2:25Speaker 03

  I like that. No, space is not that romantic. It is spaghettification.

• 2:31Speaker 01

  I swear to God, I was about to say nudification. So I was like, almost there.

• 2:34Speaker 03

  You're so close. It doesn't actually sound fun. And another weird thing happens. Your perception of time and space flips. So, you know, time gets really weird.

• 2:44Speaker 01

  OK, what's my last opportunity for humiliation?

• 2:47Speaker 02

  You're going to get this one. Do we or don't we in part owe our existence to a black hole?

• 2:55Speaker 01

  I guess we do.

• 2:57Speaker 03

  Correct. Correct, Elsa. See, you did it. So the black hole that's at the center of our galaxy, the Milky Way, also helped it form. Astronomers don't know exactly how that works, but we all have ideas.

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  All right, Elsa, so you got one out of three answers, right? But your spirit was three out of three.

• 3:17Speaker 03

  That's right.

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  Your personality is three?

• 3:20Speaker 02

  Your personality is three out of three. So in our hearts, you've won.

• 3:24Speaker 03

  Yeah.

• 3:24Speaker 02

  And this has also given us, I think, a spectacular foundation for the next part of this episode. So today on the show, what is a black hole star?

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  Listen up.

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  We also reveal some surprising exercise findings when it comes to lowering your risk for dementia and talk about a mammal that can shrink.

• 3:45Speaker 02

  You're listening to Short Wave, the science podcast from NPR.

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• 5:21Speaker 03

  OK, Elsa, you must want to start with the black hole star, right? Like astronomy is awesome, you like it.

• 5:27Speaker 01

  Of course, especially after that miniature quiz. I'm ready for some redemption. I am so hyped to beef up my space knowledge even more. So what the heckety heck is a black hole star?

• 5:39Speaker 03

  Yeah, it's totally new to science. When the James Webb Space Telescope, or JWST for short, started sending back pictures from very, very far away, meaning very early in the universe, they noticed something strange. All of these tiny, little red dots, they've never seen in space before.

• 5:56Speaker 01

  Oh, and do they have any idea what these little red dots might be?

• 6:00Speaker 03

  I mean, they had ideas. They could have been galaxies or big stars or black holes, but nobody really knew for sure.

• 6:06Speaker 02

  And a recent study published in the journal Nature puts forward an answer for at least some of these mysterious red dots, a type of object that is a black hole star.

• 6:17Speaker 01

  Huh, what is that?

• 6:18Speaker 02

  Yeah, so it's a black hole with a super dense cloud of gas and dust around it, which is kind of like the atmosphere of a star.

• 6:26Speaker 03

  But here's the difference. A regular star has basically a fusion reactor in its center. That's what makes it shine. But a black hole star does not.

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  So instead, imagine if you had something like very dense layers of gas, but instead of nuclear reactions at the center, you had a glowing black hole, a rapidly feeding black hole that was holding up this whole enterprise together.

• 6:52Speaker 02

  That's astronomer and lead author of the study Rohan Naidu at the University of Hawaii. These are not technically stars, but their light is very star-like.

• 7:00Speaker 01

  Ooh, very cool. But why haven't we seen these before? You said these things are from the beginning of time. So what, did they go extinct or something?

• 7:10Speaker 03

  That's a really good scientific question. There's this longstanding mystery how supermassive black holes, like the one at the center of the Milky Way, become that giant, like millions of times the mass of our sun. These little red dots can provide an answer. Here's Anand DeGraff, another astronomer involved in this study.

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  So we think that little red dots could be this sort of, this early growth spurt of a black hole or possibly even the birth of a supermassive black hole. And that is the most exciting part.

• 7:40Speaker 02

  Yeah, and Elsa, this all points to a new era of astronomy and discovery that the James Webb Space Telescope has ushered in, you know, finding new things much more often and getting one step closer to figuring out how these supermassive black holes form.

• 7:53Speaker 01

  Very, very cool. OK, let's move on to the next topic. It's well-established, as far as I understand, that exercise can lower your risk of dementia. That's in part why I love to exercise. But now you're telling me there's some new studies saying only certain kinds of exercise? I hope I've been doing the right ones.

• 8:11Speaker 02

  Yeah, Elsa, I think you have.

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  I'm not a doctor, but yes, you have.

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  Because my brain is so good.

• 8:18Speaker 02

  So it might not be the type of exercise, per se, but why you do it. So a new analysis in the journal The Lancet Public Health looked at 74 studies with more than 4 million participants. And they found that people who exercised by choice in their free time, like you, Elsa, you know, biking, hiking, they had lower risk of developing dementia compared to people who got their physical activity while commuting or at work. So, for example, people in physically demanding jobs actually showed a higher risk of developing dementia.

• 8:51Speaker 01

  Wow.

• 8:51Speaker 03

  So lead author Nathan Feeder at the University of Southern California says this contradicts the popular belief that any exercise is good exercise.

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  In terms of dementia prevention, every move might not count.

• 9:04Speaker 01

  Man, this seems like really crummy news for people who have very, very physical jobs. So you're telling me that people who get their exercise from, say, physical labor at work do not get the same protection from dementia as someone who's just exercising in their leisure time? That seems so unfair.

• 9:21Speaker 03

  Yeah, Nathan says that this study seems to be uncovering some of the inequities between people who exercise for fun versus people who exercise for the job. People who exercise on the job, like lifting boxes or building houses, tend to be folks with lower socioeconomic status, which is associated with higher stress, more exposure to air and noise pollution, things scientists know are linked to a higher risk of dementia.

• 9:44Speaker 02

  Yeah, clinical researcher Teresa Lou Ambrose at the University of British Columbia, who is not a part of this research, says it may also have to do with choice.

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  There might be greater stress associated with the fact that you didn't choose to do this activity and that it's hard on you and you don't have a consistent break.

• 10:00Speaker 03

  And one thing this study might indicate is that some of these risk factors for dementia, we mentioned, like higher stress, more exposure to air pollution, might weaken some of the benefits people see from exercising on the job.

• 10:11Speaker 01

  OK, so this is probably stressful news for people who work in these jobs. Is there any silver lining?

• 10:18Speaker 02

  Yeah, so Teresa and Nathan do both point out that even though the analysis looked at over 70 studies, only a handful looked at work-related exercise. So they could be missing some nuances in here.

• 10:30Speaker 03

  And Nathan says, don't be stressed if you don't have much time or energy at the end of your day to exercise. Even just a few minutes is better than nothing.

• 10:38Speaker 07

  We know that if you increase five minutes a day of leisure physical activity, we still see some benefits.

• 10:46Speaker 01

  Well, let's move on now to our final topic, shrinking shrews. Not shrieking shrews, shrinking.

• 10:53Speaker 02

  Shrinking shrews. They do shriek, I would assume. But yeah, shrews are these tiny, mice-like mammals. It can be found all over the world. And some of them, including the long-clawed shrew, which this study focuses on, have this super wild way of getting through winter.

• 11:10Speaker 01

  What?

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  So instead of fattening up like a bear or a groundhog to store up energy, they reduce the amount of energy they need by getting smaller.

• 11:18Speaker 01

  How do they get smaller? They get like skinnier?

• 11:21Speaker 02

  They literally shrink, Elsa, like, honey, I shrunk the shrew.

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  Here's Dina Dekman, behavioral ecologist at the Max Planck Institute.

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  And this includes, for example, the brain, which shrinks by a quarter, and the skull, like the ossified bone, and many, many organs. And yeah, it's super crazy.

• 11:43Speaker 03

  But then, maybe even wilder, is that when winter is over, they regrow that bone and organ tissue.

• 11:49Speaker 01

  OK, I'm sorry, but this seems like a lot of work to save energy, which is ironic.

• 11:53Speaker 02

  Yeah, evolution is a beautiful thing, right? So this is actually called Danil's phenomena. And scientists have known about this since the 1950s. But Dina says research into it has really only taken off in the last, like, decade or so, in part because of interest from biomedical researchers.

• 12:09Speaker 09

  There's lots of interest from osteoporosis research people or people who want to regrow bone.

• 12:15Speaker 03

  And researchers or doctors who want to regrow brain tissue or livers, you name it.

• 12:20Speaker 01

  Are there any other shrinking animals besides shrinking shrews?

• 12:25Speaker 02

  Well, scientists have found that other animals that are small and have like high metabolisms, like moles and weasels, they can do this in the winter. But there's still a lot to learn about this whole process, which is what this new study published by the Royal Society really shows.

• 12:40Speaker 03

  Yeah, researchers in Japan found what they coined as reverse Danil's phenomenon in long-clawed shrews, where the organs and bone shrink, but the snout gets longer in the winter.

• 12:50Speaker 02

  So the lead author says they're not really sure why the snout grows, while other parts, like the skull, shrink, maybe to enhance their ability to thermo-regulate, regulate their temperatures. But it does show how highly adapted some of these tiny animals are to seasonal changes.

• 13:05Speaker 01

  If only we were so adaptive. True, Elsa. That is so true.

• 13:10Speaker 02

  Elsa, thank you, as always, for kicking it with Short Wave.

• 13:14Speaker 03

  Such a pleasure.

• 13:15Speaker 01

  Yeah.

• 13:15Speaker 02

  If you, like me, love having as much Elsa in your life as possible, check out Consider This, NPR's afternoon podcast about what the news means for you.

• 13:25Speaker 03

  And if you liked this episode, check out our stories on what it's like to fall into a black hole and how the brain cleans up its waste while you sleep.

• 13:33Speaker 02

  This episode was produced by Burley McCoy and Kai McNamie. It was edited by Rebecca Ramirez and Christopher Intagliata.

• 13:40Speaker 03

  Tyler Jones checked the facts. Jimmy Keely and Ted Mebane were the audio engineers. I'm Regina Barber.

• 13:45Speaker 02

  And I'm Nate Rot. Thanks for listening to Short Wave, the science podcast from NPR.

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