12:11
so Brady you challenged me the other day to come up with an object to talk about for deep sky videos and I was actually kind of struggling without the Messier catalog to draw from and then it came to me there's a really nice object I don't think it counts as a deep Sky object because you can see it with your naked eye um but I thought it was worth talking about so this is the double star called alberio that is located in the constellation signis so signis is the swan it's one of the only constellations that actually looks like the thing it's supposed to represent you can actually see sort of the long neck and at the end of the neck is a bright star called beta signy also known as alberio and this
will be known to anyone who does a little bit of amateur stargazing because it's a really accessible Target if you look at it with a small telescope what appears to be a single star to the naked eye resolves itself into a really nice double but what really sets it apart are the Striking color differences between the two stars and you can see this when you look through the telescope so you've seen this book before constellations as seen in Southern India yeah so this was a book written by my great-grandfather also an astronomer and he wrote about this his name is Robert John pook was and he says Albero is a beautiful double star uh the colors of the two stars are golden yellow and sapphire blue and the
pair forms perhaps the loveliest contrast of colors to be found in the heavens so I thought we were going to do a little video about the colors of stars and we were going to talk about how the color actually tells us a bit about the temperature and that Bluer Stars tend to be hotter and red stars tend to be cooler relatively speaking um but the more I read about Albero the more uh intrigued and confused I became because what looks like a double star actually as we look more closely reveals itself to be a far more complicated system so pook didn't know this pook didn't know this nobody really knew this until quite recently because we didn't have the uh capability to make those kinds of
measurements so if we start I'm going to get my props out so I can keep things keep track of things we have our two stars so we're going to call them Albero capital A and Albero capital B these are the ones pook did know yeah these are the ones pook did know so a is the um yellow one it's slightly brighter B is the Bluer slightly dimmer one astronomers have been observing these objects for over a hundred years in fact when I went to look at the literature and pulled up all of the papers on this object to learn more about it the oldest one was from 1897 and because astronomers have digitized and archived all the published papers we can show you that paper and so there's a mystery around these
two to begin with which is they appear to be next to each other on the sky but are they actually a physical double do they actually orbit around one another and Keen viewers of this channel this will sound familiar to you because of course when uh we did M40 that was one of the questions in the Messier cataler there was one object that was a double star and the big question mark was uh is this is this a double well how could they not be one could be in the foreground yeah one could be in the foreground one could be a long way away and until you get um some sort of measurement on their actual distances uh you can't tell them apart M40 led to a very illustrious publication by Maryfield gray and Haron um actually
revealing from the Gaia telescope once sufficiently good data was released that in fact was not a double those stars were physically separate so these two bonded that's the question well still unclear so even with the great data from all of these telescopes from the guia mission which releases more and more data in separate releases it's still a little unsure part of the reason is that they're actually really bright and that can cause just as much problem for making good measurements as something being too faint the suggestion was unlikely if they were a pair they'd be a very long orbit but we hadn't actually pinned the error bars down those all important error bars to be sure but there's another problem
measuring the motion of this star Albero a becomes difficult because there are signs that it itself is a binary pair so if you think about measuring the relative motions of different Stars we call this the proper motion of stars this is comp licated by the fact that we're moving through the Galaxy they're moving through the Galaxy we're moving around the Sun and if they are in a binary pair they're wobbling as well so things get quite complicated quite quickly but there's indications that alberio a is in fact a double so I'm going to take this one away and I'm going to replace it with Albero a and Albero a c okay so these are too close together to be distinguished on the sky as separate objects but we can use lots of different
techniques to learn about them and so in a paper from 2021 and I really like this title um it's called a Celestial matoska you know those nesting Russian dolls basically the authors threw everything that they could at this system to try to learn about it and they discovered that this pair was made up of a red giant and a blue main sequence star so a star that's just normally fusing hydrogen and they had masses of 5.2 time the mass of our sun and 2.7 time the mass of the Sun and they orbit each other with a period of around 120 years Okay so we've learned something about this but there's always a butt it's still not satisfactory because if you do a separate analysis of the orbit of this pair itself the mass has come out the
wrong way so there's an indication that there's there's too much mass in this system and there's there's something else there and this is where this idea of nesting dolls come in and so it is quite possible that alberio AC is too massive that there's some hidden Mass there and so the question mark is what might that be and so perhap perhaps it itself has a companion and whenever we talk about hidden Mass we always raise the idea that it might be a little black hole um that has not yet been confirmed that's just a hypothesis but it's interesting because I think if I'm correct if it were confirmed that had a black hole orbiting around it that would be the closest black hole to Earth
because it is only a few hundred light years away but the story doesn't end there because uh another paper came out with another great title which was yet another star in the alberio system and so this paper again looked carefully at radial motions and this time suggested that there is an additional member of this system possibly in orbit around Albero AA which we're going to call Albero a d and this is likely to be a very low mass star indications come from the radial velocity measurements much smaller than the sun orbiting around this with a period of about 371 days so not too dissimilar from the Earth's orbit around the Sun so what was a beautiful double system now looks like quite a crowded system there's a
little bit more information coming W more widely one of these papers uh suggested that there are four additional sort of associated Stars nearby that might not be physically found in an orbit but might have some physical Association and also the analysis of The Originals AA and ab suggests that they were probably formed in the same place and at the same time they're what we call coeval so while they might not be an orbital pair they probably came from the same gas cloud when they formed and in fact what we might be seeing is the remnant core of a dissolving open cluster so an association of stars that all formed about the same time um but were not gravitationally sufficiently bound to retain uh a
physical Association and are just sort of drifting apart just so I'm clear B our dark blue one there one of the original two the og2 yeah that's the current thinking is that's not gravitationally bound to the others it's it's it's far away now like it's either in the foreground or the background yes that's the indication they're not too far away but they're probably too far away to be physically bound so let's move this over here we're not entirely sure the connection but it's unlikely to be part of this conglomeration that we see over here but visually what we're mainly seeing is AA the red one there and that one and the yellow the aqua one and the black hole we don't really see without some hardcore analysis yeah
so hidden behind the view of what looks like this in our telescope uh when we see our beautiful different colored pairs what is actually in reality behind it is something possibly that looks like this thanks for watching we'll put links in all the usual places including a link to our playlist of videos all about the messier objects and a playlist of videos I've made filming at telescopes all around the world like the one you see on the screen at the moment and speaking of things you see on the screen at the moment see these names these are some of our patreon supporters please if you can spare a dollar or two consider supporting us on patreon it helps us make more videos and we'll share extra
little stuff with you on bonus goodies and you know maybe put your name here too see your name floating through signus that's something you don't see every day
