🚀 Add to Chrome – It’s Free - YouTube Summarizer
Category: Astronomy
Tags: AstronomyBinaryDiscoveryHubbleStars
Entities: AntonHubble Space TelescopeMilky WayNGC 3603A1NGC 363R136 A1Sarah BodanskyTarantula NebulaWR21A
00:00
Hello wonderful person. This is Anton and today we're going to discuss another fascinating discovery from right here in the Milky Way galaxy.
Another record holder, but specifically what seems to be the most massive binary star system ever seen, at least within our one
00:16
galaxy. But in this case, a star system that's also kind of bizarre and doesn't actually make a lot of sense.
And so let's discuss this discovery and also briefly talk about some other massive stars already known to us with all of this based on the recent study from the research team you see right here that
00:31
use both archival footage and new observations mostly using the Hubble Space Telescope in order to precisely measure the properties of a binary system known as NGC 3603A1 and confirming that the system represents one of the most massive
00:47
binary systems ever discovered. Way way bigger than we thought.
And so I guess let's start with the exact properties. First of all, this is not close to us.
22,000 lighty years away and it's inside a very vibrant starburst region referred to as NGC 363.
01:03
The beautiful star forming region in the southern Milky Way that's known for a lot of massive young stars. And so this is an active cosmic factory producing huge amounts of stars.
And this is also the most massive visible cloud of gas in the entire galaxy, potentially making
01:19
this the most active region in the Milky Way, possibly producing the most stars. But this is also one of the closest such regions to planet Earth, making this extremely important for astronomy because it obviously teaches us quite a lot about star formation.
And quite a few really massive, very active stars
01:36
have already been discovered with a lot of these stars being very massive wolf ray stars responsible for very bright, very massive emissions and huge amounts of gas and dust released at all times. And some of these stars are super bright, millions of times brighter than
01:52
the sun. And there's actually quite a lot of them in this region.
But at least one of the objects here kind of stood out. You can sort of see it right here.
And at first it was believed to be just a single star referred to as HD97950. But it turned out to be at least three
02:08
different stars with one of these objects being the pair we're discussing today. And so here we have two stellar titans.
The primary star is approximately 93.3 solar masses and its companion is 70.4 solar masses. So this
02:23
whole system is over 163 solar masses in total which if compared to some of the other most massive stars discovered to date would make it like number five or so but number one in the Milky Way and that's because most of the massive stars known to us are all basically right here
02:39
the Tarantula Nebula. the large concentration of stars in the nearby large Melani cloud that contains some of the biggest record holders and some of the most massive, brightest, and most active stars ever discovered.
And all of the stars in the Tarantula Nebula and
02:55
this newly discovered binary are not just large stars. They're essentially at what seems to be the practical limit of stellar masses.
Or just to rephrase this, astronomers don't think stars can even get more massive than this. But what makes this system truly extraordinary is also the orbit of the
03:10
stars. The orbital period of these two bizarre giants is just 3.2 days which was recently confirmed in a study in a description.
And so this very close proximity and this enormous gravitational pool potentially creates very dynamic and very complex
03:26
relationship between these two objects. But this discovery and the analysis was relatively complex.
It involved years of careful work and the observations of NGC 363 star cluster which by itself is already pretty challenging mostly because many stars here seem to be
03:42
concentrated in a very small region and all of this required exceptional clarity from the Hubble Space Telescope. But the breakthrough came in 2020 when during the COVID lockdown, the undergraduate student Sarah Bodansky remotely used one of the observatories to look through
03:58
some of the older Hubble data and accidentally discovered something we've never seen before. She noticed that a lot of spectral features doubled when the stars had their greatest motion towards or away from us, which revealed that this was a binary system and not just a single fuzzy star.
And
04:14
specifically, she was able to identify that certain Balmer lines or certain hydrogen lines were clearly doubled and were clearly separated as if there was a certain orbital phase which allowed the researchers to determine the exact radial velocity even though it was disturbed by various stellar winds. And
04:30
this led to a very precise orbital parameters and a very precise mass measurements. And so by measuring radial velocity of both components and also determining the orbital inclination, by using Kepler's laws of planetary motion, we can then directly calculate the mass
04:46
of stars. But it's also important to note that these extremely massive stars are actually super rare.
And their study usually involves looking at very distant and very crowded regions such as the previously mentioned Tarantula Nebula. But based on a lot of previous discoveries now researchers are pretty
05:01
certain that for some reason most of these massive stars or basically over 70% of them seem to always come as a binary and they always undergo significant interaction during their lifetimes that then play a huge role in the evolution of stars, evolution of everything around them and the ultimate
05:19
fate of the cluster and any other stars in the vicinity. and specifically these very massive binary systems very often also serve as progenitors of very powerful supernova and binary black holes which eventually results in the gravitational wave detections we've been
05:34
detecting since 2015. And so here we get at least one chance to potentially predict what kind of a system this is going to create in the next million years.
But the weirdness of the system doesn't end there. Here, the most massive star, the one that's 93.3 solar masses, is currently filling its ro
05:51
surface. Or just to rephrase this, its outer layers are currently being gravitationally stripped away and transferred to the companion, the smaller secondary star.
with this kind of a mass transfer being a very critical process in the binary stellar evolution.
06:07
As a matter of fact, at some point they might even form what's known as the contact binary where both stars sort of kiss and touch each other. But this of course has a lot of effect on the secondary star as well.
The secondary star with the 70.4 solar masses has now
06:22
been observed to be spinning much much faster than its synchronous orbital speed. Here it seems to be spinning at 520 km/s, which is something like 40% of its theoretical breakup velocity.
In other words, if it starts spinning even faster, it's at some point going to
06:39
start falling apart. And this rapid rotation is a strong indicator that the secondary has now been spun up by consuming a lot of mass and angular momentum from the much larger companion.
Essentially confirming that the larger star is feeding the smaller one. But
06:54
here even the classification of these stars is also kind of strange. They're now identified as O2 WN/ stars indicating that despite being somewhat young and somewhat unevolved, their extreme luminosity is pushing them close to the absolute luminosity limit.
The
07:11
limit where the luminosity becomes so powerful and so bright that the radiation pressure generated by nuclear fusion starts to exceed gravitational pool or basically the star becomes so bright that the light starts to push everything away from it with the gravity unable to hold it anymore and this
07:28
usually leads to the formation of very dense optically thick stellar winds that then produce very beautiful nebula such as the one seen around wolfy stars but in this case it's just a case of very young stars appearing much more evolved than they should be. And all this just a
07:43
result of this extreme interaction and extreme activity. But the strangeness of these stars doesn't end there.
We also have something unexplained about the temperatures. For some reason, the secondary star is about 5,000 Kelvin hotter than the much more massive primary star.
Here, the smaller star is
08:00
42,000. The bigger star is 37,000 Kelvin.
And this is also maybe the result of the secretion or basically the star eating the mass from the other star which seems to have changed the thermal equilibrium. And that also seems to cause the larger star to now evolve much
08:16
faster than it would otherwise cooling down much faster than it should. But how exactly does the star compare to some of the other giant stars?
Well, right now in the Milky Way, this is literally the record holder with maybe one other system, WR21A, located in the Korean Nebula known to
08:33
have a somewhat similar primary star with 93.2 solar masses. But in essence, there are only like four such stars known to us in the entire Milky Way.
And though I guess the most famous is at Karina, the one that produced the infamous homunculus nebula. Even here,
08:48
the star system is a little bit smaller. Its mass is very likely much lower, but it's also currently impossible to measure because of this enormous eruption in the mid 19th century.
This is of course the famous Great eruption that you can learn more about in one of the videos in the description. But when
09:04
it comes to other star systems in the nearby Tarantula Nebula, there seem to be some stars that are even more massive with the most famous one R136 A1. Once again, you can learn about this in the description below.
Possibly having a total mass of nearly 290 solar masses
09:19
based on several observations. But here we don't actually know if this is a single star or a star system containing multiple stars.
Mostly because this is pretty far away from us in the large melanic cloud or danger. One of the recent studies confirmed that most of this mass is eventually going to be lost
09:34
through enormous stellar emissions over the next million years. And so even though these stars start with hundreds of solar masses, they'll eventually lose possibly up to half of this, creating a massive nebula around the system.
And so here by studying some of the more nearby such systems such as NGC 3603A1 we're
09:51
discussing today, it provides astronomers with a very unique opportunity to test ideas and various theories and to try to explain how stars evolve, how these massive giants affect various stars in the vicinity and how all of this mass loss eventually results in the formation of stellar dust.
10:08
Because as we know today, most of this dust actually produces organic molecules and a lot of this potentially ends up in various planets. And so in some sense, these really massive, really bright stars serve as a kind of a precursor to a lot of complex stellar systems, including systems with terrestrial
10:24
planets. And so the influence of these stars and their incredibly powerful interactions goes way beyond just a simple interaction and actually ends up enriching the entire region around them with many very complex elements potentially serving as building blocks of life.
And that's because the stellar
10:40
wind from these stars ends up producing a lot of organic molecules with this study revealing phenomena like rapid rotation and very specific spectral characteristics that seem to arise from very close interactions of very massive stars. But I'm sure in the next few months as this star is explored even
10:56
more, we'll probably discover something else, which means that we'll come back and discuss this more in some of the future videos. And until then, thank you for watching.
Subscribe, come back tomorrow to learn something else. Support the channel on Patreon where you can find additional videos, videos without any ads and can DM me directly or by joining channel membership that
11:12
grants you early access and a few more things. Alternatively, you can also buy the wonderful person t-shirt in the description.
Stay wonderful. I'll see you tomorrow and as always, bye-bye.
11:27
[Music] [Music]
11:48
[Music]
12:41
[Music]