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May 20, 2010 14 mins

Like most things in the universe, stars begin as particles floating around in massive clouds of dust and gas. But what forces these particles to coalesce and form a star? Tune in and learn more about the birth of stars in this podcast.

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Speaker 1 (00:01):
Welcome to Stuff from the Science Lab from how stuff
works dot com. Wow, hey guys, and welcome to the podcast.
This is Alison I don't know, the science editor at
the how stuff works dot com, And this is Robert Lamb,
science writer at how stuff works dot com. Today we're

(00:23):
going to do the first podcast in a recurring series
that will look at how different celestial bodies get their start,
and we're gonna begin with stars. Yeah. Do you know
what a supergroup is, Alison? Tell me what a supergroup is, Robert,
But something like you two. No, no, no, okay, you
two is a group that you know, these guys came together,
you know, started small, and they became this, you know,
this awesome musical act. Right, Um, I don't know. I'm

(00:46):
talking about like established you know names, and they're they're
just pulled together by their own you know, awesomeness and
they form a supergroup. You know. It's kind of like
a like a voltron of music. Like a couple of
classic amples are like the Traveling Willbury's the eighties. This
is Bob Dylan, George Harris and Tom Petty, Jeff Lynn

(01:07):
of Electric Light Orchestra, Roy Orbison all come together and
really don't make anything memorable, but that they still they
come together in an awesome group, right the Highwaymen, that
was Wayalen Jennings, Johnny Cash, Chris Kristofferson, Willie Nelson. You know,
they come together just drawn together by and just become
something in theory awesome, you know, not like like Wu

(01:27):
Tang clan would not be an example because like those
guys all started off together as Wu Tang and then
they became awesome, and then you know, went off into
their own thing and then came back. But now these
are these are people are just drawn together and they
become a supergroup. So that's what I keep thinking of
when I was reading all about star formation and really
the formation of a lot of things in our in

(01:49):
our universe due to a process called accretion. Yeah, so
let's take it from the top, Shelley. In the process
of star birth. Yeah, like most things in our thirteen
points seventy five billion year old universe, stars begin as
just particles or began as particles just floating around in
these vast clouds of dust and gas um and these

(02:11):
clouds which we know as nebula. Uh, they don't do
a lot of anything for while they're cold, they're monotonous.
Nothing's happening, right, just little particles out there, you know,
like a little bitty you know, nobody's on the music scene,
just out there in space. Just play in the clubs
open for a big break. Yeah. Then what happens then?
Like some sleepy backwater town and a biker movie. I

(02:32):
think classic movie Wild One. That would be the film analogy.
And by the way, I don't think you've seen Wild One?
Have you film Star? No? No, I have not seen
seen that. Yeah, I do like ribbing that in because
you've seen pretty much every movie. What do you think
of that movie? And I have not seen any movies
including Wild One. Uh. But but the idea is pretty simple.
It's like sleepytown and the name comes the biker, right, everything,

(02:54):
everything gets all crazy when this newcomer speeds through. In
the case of a star, that disturbance might take the
farm of a streaking comment or the shockwave from a
distant superdova, rather than say Marlon Brando riding on a
Triumph Thunderbird and playing the leader of a motorcycle gang.
Have you seen it Triumph Thunderbird? We have a picture
of one on our side it's pretty it's pretty cool.
A thunderbird, you mean the classic like native American bird

(03:17):
that No, no, I mean like a cycle, like a
bike that all vehicles look the same to me. So
what happens next? Alright? So alright, so yeah, everything gets
stirred up by our you know, cosmic biker gang that
rolls through the town, through town. So all those particles
starts spinning around, right, and when you have all those
particles moving, suddenly you have collisions. Collisions occur. Now, this

(03:39):
is where creation begins because clumps. Yeah, you start getting
clumps and a clump of particles, just even a small
clump of particles um ends up having a gravitational pull
on other clumps. So they start, you know, clumping together
in fluence. And and this is actual the actual term.
Astrophysicists used the term clumps. So we're not it's highly scientistic.

(03:59):
We're not domine it on anymore than it I mean,
it's a clump. It's kind of like that game. I
have to mention this. Have you ever played Katamari Domacy? No, no, no,
what's up. It's a it's a video game that was
for PS two sixty. Number of these games all right,
So the idea is, you can't see me, but I'm
rolling my ass. That's a silly question to ask, but
it's a it's a Japanese video game and it it

(04:22):
involves the Prince of the Universe accidentally destroys the stars.
So he charges this young prince with creating new stars.
And you're the prince and you're very smallest, tiny little guy,
and you have this little ball and you roll it
around and as you roll it around, it starts other
objects starts sticking to it. And it starts off small,
so it's like paper clips stick to it, you know,
thumb tacks. And then the ball stars getting bigger and

(04:43):
it just rolls, you know, rolls up to your rolling
up say, mice, um erasers, m chairs, tables. Eventually you're
rolling up like whole houses. And if it gets big enough,
the King of the Universe is this big mustachio guy
with a fancy hat, takes it and turns it into
a star. And really that that's the process. It's one
of the silliest games I've ever played. And it's a blast.

(05:04):
But that's basically accretion, right, So it's more matter falls
into the clump. It's center is gonna grow denser, and
it's gonna and it's gonna grow hotter. Over the course
of a million years, the clump grows into a small
dense body and it's called a proto star. And this
protot star continues to draw and even more gas, and
it gets even hotter. Yeah, and eventually our protostar gets

(05:26):
hot enough. And we're talking seven million degrees kelvin um.
And remember that the sign signs use kelvin scale when
they're talking about very high temperatures, very low temperatures. Zero
kelvin is absolute zero. That you know, nothing can really
touch a theoretical temperature if you will, I will um.

(05:48):
So it gets hot enough, the hydrogen atoms. The hydrogen
atoms begin to fuse, producing helium in an outflow of energy.
All right, bang nuclear fusion. How he, the outward push
of its fusion energy is still weaker than the inward
pull of gravity. So you have this tug of war
going on with the opposing forces in the young star's life.

(06:09):
You made the point that it's kind of like a
struggling business that's still costs more to operate than it makes. Yeah,
it's still is still pulling in more than it can
push out, so it hasn't stabilized yet into a mature
adult star. But material continues to flow into the protostar,
providing increased mass and heat. And then, finally, after millions
of years, uh, some of these struggling stars reach the
tipping point. Sort of fireworks gone on. Yeah, if if enough,

(06:33):
if they reach enough mass, which is roughly point one
solar masses, And a reminder, one solar mass equals our sun.
You know, it's the closest star we have, so that's
our our measuring stick for everything else. Um, some point
one solar mass is obviously going to be smaller than that. Yeah,
reaches that point, it and it will collapse into the
protostar and it produces this thing called a bipolar flow,

(06:55):
and that just means two massive gas jets erupting from
opposite sides of the protostar and it just just blast
the remaining gas and dust clear away from the fiery
surface of the star and bang. Just like that, the
young star stabilizes and like a business, it finally becomes lucrative.
It reaches the point where its output exceeds its intake.
The Howard pressure from hydrogen fusion now counteracts gravity is

(07:18):
in a red pull. It's a main s you can
star and it will remain so until it burns through
all its fuel, which brings us to our next question. Yeah,
the lifespan of the stars. Got back to the business thing.
You know, some businesses are run very well um, and
some businesses, uh are run very poorly. UM. So it
it's similar with the stars. It depends on the mass
A star. The size of our Sun takes roughly fifty

(07:40):
million years to reach main sequence and maintains that level
for approximately ten billion years UM. Astronomers classify the Sun
is a G type main sequence star. The G indicates
the Sun's temperature and color. Right, Astronomers have to have
some way to classify all the stars in the sky,
so they invented Oh, be a fine girl, kiss me.
Have you heard this? This is cool. It's anemonic device,

(08:03):
and the first letter in each word of the pnemonic
device corresponds to one of the spectral classes. So for
the oh and O star is going to be the
hottest with temperatures between thirty thousand and sixty THO Kelevins
and an O star is blue. Yeah, that reminds me
the thing with the rainbows and the lebricn what's the
name of what's that lucky charms? No, no, no, he
talking about it's like like some words, some nonsense cool word.

(08:25):
It stands for all the different hues the Yeah, that's
nothing like that. I highly disagree. Um. So, after you
have your O star, then you have less odd B stars,
which have tempts between ten thousand and thirty thousand calevns,
and these are gonna be blue white. Then you have
your A stars. I won't tell you the temperatures here
because you're gonna forget him. This is a podcast. After all.
These A stars are why you have F stars. And

(08:47):
then you have GES stars. These are yellow like our sun.
And by the way, if you guys don't know it,
there is a podcast out on how the sun works
that Josh and checked it, so if you want a
little bit more background on the sun, that might be
a good one to listen to. After your stars, you
have K stars. These are gonna be yellow orange. And lastly,
all the way at the bottom of the list are
M stars, which are red and are less than thirty Kelvin's.

(09:09):
But you don't have to remember all that, Just remember, oh,
be a fine girl and kiss me. You can also
group stars depending on whether or not they have a
maine so a binary star, for example, or whether they
occur in clusters or otherwise, or maybe you're more interested
in measuring luminosity, radius, movement, mass or more. Uh. Now,
of course, the larger, brighter stars are going to burn
out faster. Um wolf rayet stars boast masses at least

(09:33):
twenty times that of our science. That's twenty solar masses
and burn four point five times. It's hot. Uh, they
go super supernova within a million years of reaching the
main sequence. It's more like Starlet, you know, rises up
fast on the Hollywood scene, makes a big splash and
band nobody's heard of him in five years exactly, flash
in the pan. That about wraps it up for starbirth.

(09:55):
You know that sounds a lot like starburst if you
say it fast. By the way, did you know that
starboard we're first called opal fruits. Yeah, they're when they
were first invented in the UK nineteen but when they
came to the US, the Americans changed the name to
star wars. I had to wonder if this had something
to do with the space race. Maybe, so I searched
the Google and I could not find anything. I wonder

(10:16):
Opal where? How Opal fruits taste? I know I want
to have one. I don't know. I think you should
go downstairs after we finished recording and get some Star
Wars and give me one. Please. You know what I'm
excited about. What are you excited about, Robert Um. I'm
excited about our Twitter and our Facebook. Tweeting is pretty fun.
What's our handle? Our handle on Twitter is lab stuff. Yeah,
and you can become a fan of us on Facebook two. Yeah,

(10:39):
where we're just stuff in the science lab. You can
just searches. You don't even have to put you in
around the starch and just start showing up. Yeah. We
got a brand spanking news stuff from the Science Lab
page on Facebook. Yeah, and yeah we're gonna we're keeping
that updated with you know stuff, We've written stuff, we
are writing stuff. We're thinking about writing queries for people
with genetics expertise, all sorts of good stuff. And about

(10:59):
a spy iter that eats tonails. What was that? Yeah?
That was pretty crazy, spider. So I think that's about it.
You want to do some listener mail, Yeah, I've got
some pretty cool listenermail here. Well, recently we did that
whole podcast about venom and things we can do with
venom such as turn it into medicine or or drink

(11:21):
it or drink it. Yeah, so this one here comes
from Paul in London. He says, Hi, Allison and Robert,
my name is Paul, and I live in London, England.
I just can you go back to you with a
British accent feast? I don't know. Was that be tasteful?
Maybe not? Okay, forget that. I thought you do a
pretty good British accent too. Okay, but sorry, I don't

(11:41):
I can do it. Just understand that there's no um,
you know, I wish I had a British accent. So
it's it's really more sad than it is distasteful. Um.
Hi Allison and Robert, my name is Paul. You know
I live in London, England. I've just listened to your
Virtues of Venom podcast and I thought I would email
you to let you know about my personal experiences with
snake wine. While traveling in Vietnam, I was convinced by

(12:04):
an older Vietnamese baki to consume a shot or three
of snake wine He said that it would make me
quote a strong man while he made a fish showing
how it would work as an half a daisy act.
I'll be honest, I'm not sure about the review you
read read out in the podcast. It didn't taste like
jin sing. I just remember it burning. I believe that

(12:26):
there's also snake blood and snake bile wine, but thankfully
I have not experienced either of these. Keep up the
great work, Paul. Yeah, so I'm I that wasn't It
was awesome to hear about even more snake than him
related beverages out there. And uh yeah, I mean and
and if anybody else, Yeah, send me more reviews because
I need to do a little research before actually order

(12:47):
a bottle. What else are you holding? Then you're in there?
Oh let's see, I've got one from Jeffrey and I
don't know where Jeffrey's froms like, just gonna use my
own accent. Hey, guys, just finished listen in to the
podcast on venom, and Robert mentioned the idea of venom
and energy drinks. I remember a couple of years ago
reading that reading this wasp in Korea whose venom is

(13:10):
used in energy drinks or at least a component of
the venom and it's raw state. The venom dissolves flesh,
and people that get swarmed who don't die are pretty
much disfigured for life. If I wasn't on my phone,
i'd send you a link, but I had to mention it.
Keep up a good work, Jeffrey sent from my iPhone. So, um, yeah,
that's that's awesome. I looked it up a little um

(13:32):
and um and yeah. Apparently apparently these energy drinks are
at least pretending to be made from some sort of
like crazy wasp juice, so it's pretty interesting. Cool. Well,
thanks for writing, as we always love hearing from you,
and as always, if you want to send us an
email about stars or anything else scientifics and it's an
email at science stuff at how strix dot com. For

(14:02):
more on this and thousands of other topics, is it
how stuff works dot com. Want more how stuff works,
check out our blogs on the house stuff works dot
com home page

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