Impossible Binaries

It’s not often that you see young Earth creationists trumpeting a study that on the face of it would seem to show a universe even older than is currently generally accepted. But that’s exactly what Brian Thomas’ Four Sets of ‘Impossible’ Stars does:

Astronomers just found four binary star systems that should not exist if the universe is only 13.7 billion years old. These stars look twice that old to secularists, because they are rotating around one another in less than four hours. Perhaps God placed them there in order to challenge the origins myth that is espoused by evolutionary scientists.

If the ICR suddenly went belly-up I could potentially re-purpose this blog to discussing, or simply listing things “that should not exist if the universe” were only 6000 years old – that would not be hard.

Now, what’s up? Binary (that is, double) stars slowly spiral into each other over a period of billions of years as while the conservation of angular momentum should keep them spinning at a constant rate there are forces that will, eventually, take away this momentum. For a certain type of red dwarf star there is a cut-off at an orbital period of 0.22 days (~five and a quarter hours) where no pairs have been observed as taking less time to circle each other.

It was theorised that there must be a minimum distance that these stars can form from each other least they merge during the process – this fact seems fairly solid regardless, I’ll note – and that binaries with periods of less than five hours would not have had time to decay to that state and thus should not exist. Simple!

Ruining the fun comes the discovery of four pairs of M-dwarf binary stars that have periods much shorter than .22 days, as low as .112 (2 hours, 40 minutes) in one case.

So how can this be? The “explanation” (really, consequence) that Thomas wishes to make the most of is that the universe is significantly older than 13.7 billion years. Needless to say, this is unlikely:

The research team spotted one pair of stars that orbits every 2.5 hours. The universe would have to be about 28 billion years old to accommodate such stars, assuming they followed the standard mass loss schedule. Nobody wants to accept that.

A point about this “28 billion years” figure: Thomas appears to have made that up himself (it appears neither in the paper nor in Thomas’ space.com article). The reasoning he most likely used is that as .112 is just under half of .22 then the necessary age of the universe would have to be just over twice what we think it is, i.e. 28 billion years.

Unfortunately for him, the decay in orbital period is not linear, and in fact increases as the distance gets smaller. This ruins his back-of-the-envelope calculation and suggests that Thomas may well not have so much as looked at the pretty pictures in this paper and is instead merely parroting Jason Lisle, who we will get to in time. That being said, you would indeed need to increase the age of the universe substantially to accommodate these stars – but 28 billion years is much too far.

So something needs to give, but if it’s not to be the age of the universe then what is it?

One explanation for this acceleration is called “magnetic braking.” It describes how stars could lose angular momentum through mass loss, a very slow process in theory.

By my reading this is a little off – I don’t think it’s the mass loss that is supposed to lose the momentum, but interaction between the magnetic fields of the stars. One possible explanation, therefore, is that this effect is much stronger in red dwarfs than in the stars that we are more familiar with:

Another possibility [aside from the stars having simply formed closer together in the first place] is that the evolution of M-dwarf binaries is faster than expected. M-dwarfs are known to be active and flaring stars. West et al. (2011) find an activity fraction of 40-80% for M4-M9 dwarfs, which implies that scaling solar type stars to M-dwarfs is not trivial. It is possible that because of the (near-) convective nature of midto-late type M-dwarfs that the ultra-short periods of our binaries, when synchronised with the stellar rotation, cause the magnetic field lines to be significantly twisted (the α2 dynamo; Radler et al. 1990). In other words, the topology of the magnetic fields could be significantly different from that of solar-type stars, which may directly affect the overall activity and as a consequence the rate at which angular momentum is lost.

We also have the possibility of unexpected funny-business in the formation of the stars:

Alternatively, the formation mechanism for M-dwarfs may be different from that of earlier type main sequence stars. It is possible that during the pre-main sequence phase an excess amount of angular momentum is removed which accelerates the orbital evolution. Possible sources of such enhanced evolution could be dynamical interactions with other stars, accretion of the surrounding material and/or interaction with a circumbinary disk (Pringle 1991; Artymowicz et al. 1991; Bate & Bonnell 1997). The hydrodynamical calculations of binary formation by fragmentation of Bate et al. (2002) indicate that proto-binaries potentially form with large separations (> 10 AU) and go through a phase of accretion and orbital evolution towards tighter orbits (∼ 1 AU). Less is known about the later phases of orbital evolution.

So there are a few options.

Thomas concludes his article with a quote from Lisle, coming from a recent “personal communication” of some kind:

The discovery of stars with a period of HALF the theoretical minimum is surprising from a secular point of view. It indicates (1) the universe is much, much older than the Big Bang allows (a conclusion that secular astronomers will immediately reject), (2) the magnetic braking mechanism is much more efficient than theoretical predictions, (3) some other natural mechanism is responsible, or (4) the universe was supernaturally created, with binaries already in place.

As you can see, the fourth option (which is what the creationists really want) is more than a little unlikely in and of itself. But consider it, for a moment, along with what Thomas said at the start:

Perhaps God placed them there in order to challenge the origins myth that is espoused by evolutionary scientists.

What they are effectively saying is that God planned for the creation of “evolutionary” theories and built a universe that would lead them on until the surprise of a few inexplicable data points is revealed? Seems a little odd, in the circumstances.

Do the creationists have an explanation for the observed phenomena, beyond “God did it and He moves in mysterious ways”? No. Their only answer to the observation of the cut-off with a handful of stars beyond seems to be that God is screwing with us. What a theology that would be.

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4 thoughts on “Impossible Binaries

  1. I love the way the fourth option stands out, and they kind of acknowledge it. They can offer no justification for picking the fourth one and don’t even try.

  2. Red dwarf stars are thought to be able to last hundreds of billions of years! The Milky Way is thought to be around £13 billion years old.
    “Early in their lifetimes, stars shrink in size, which suggests that the orbits of stars in these tight binary systems must have also shrunk since they were formed, the researchers said. If not, the stars would have interacted with each other early on, and would have likely merged.
    But, how the orbits of stars in these binaries shrunk by so much remains a mystery. According to the new study, one possible explanation is that cool stars in binary systems are much more active and violent than was previously thought.
    As the cool stellar companions spiral in toward each other, their magnetic field lines may become twisted and deformed. This powerful magnetic activity may help slow down the spinning stars, allowing them to move closer together, the researchers explained”.
    Loss of angular momentum.

    According to Mr Thomas: “”This suggests that evolution timescales are too long for M-dwarf binaries to decay into tight orbits within the age of the Universe,” according to the new finding”. However NO such sentence appears in the Abstract here: http://arxiv.org/abs/1206.1200

  3. YECs have never been ones for theology beyond the “plain reading of scripture” so their idea of God is pretty infantile and would include a god who is a stand-up comedian as well as judge, jury and executioner.

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