Just an amazing experience heading up to the beautiful Pilbara region of West Australia to speak about aboriginal astronomy. I was part of an amazing lineup of speakers and events for the Karijini Experience, featuring everything from indigenous basket weaving techniques to Opera in the Gorge by the incomparable Deborah Cheetham
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This new high resolution study of neutral hydrogen (HI) in local galaxies, led by Baerbel Koribalska has a great name LVHIS (almost pronounced Elvis... which is reason enough to look at this work). It's also a fantastically thorough and exhaustive study into the kinematic properties of 12 nearby dwarf galaxies. The study of galaxy rotations using the HI line isn't anything new of course, but the dataset presented here represents the quality of data that we can routinely expect from the forthcoming Australian Square Kilometre Array Pathfinder (ASKAP) and hence is a valuable guide into the uses (and pitfalls) of high resolution kinematic data.
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This is a summary of 3 papers released today by the above authors (who all shuffle in order dependent on the exact paper) but basically it's a way to improve the measurements of the Baryonic Acoustic Oscillation (BAO) using the Sloan Digital Sky Survey Data Release 7 sample of galaxies... So of course the first question is, what's the BAO?
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The latest 'citizen science' project to hit the astronomical shelves is a really fun investigation into the HII (ionised hydrogen) bubbles that form around young, ionising stars or Supernovae explosions. The issue here is that they can be very complex shapes as the shock wave around such ionising sources will typically flow around dense interstellar gas. This means that identifying such objects will be difficult for automated systems but easy for humans with our pretty impressive pattern recognition skills. This is the idea of the project - harness the power of people for a problem that we can uniquely solve.
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A series of N-body simulations (so gravity only, no worrying about computationally expensive, or indeed theoretically poorly understood gas and stellar physics) of objects that are of similar total mass to the Milky Way halo. So far so Aquarius (which indeed this paper uses) but the nice take on the problem is that the Dark Matter is assumed to self-interact. There's no theoretical reason why it shouldn't (and indeed they reference a Yukawa-like gauge boson interaction that might have just such a velocity-dependent interaction cross-section) but that's beyond my area of expertise, besides it's not a new idea so feel free to wiki it probably. Instead all we need to know is that this could happen and if so, what are the consequences of Dark Matter that can?
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