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Cougar
2014-Aug-06, 10:45 PM
I was looking at Martin acoustic guitars recently. They're still very expensive. A standard D-18 or D-28 dreadnought probably starts around $1,500 and can quickly reach $3,000 and higher. But Martin has come out with a much less expensive model, the D-1X. It's less expensive because it's a laminate acoustic. Laminates are very common in electrics, but considered an anathema to discriminating acoustic guitarists.

So now we've got word of a new "species" of Supernova Ia -- the Iax (http://hubblesite.org/newscenter/archive/releases/2014/32/full/). It's apparently a cheap imitation of the classic Sne Ia. :doh: What's somewhat disturbing is that these weaker supernovas originate from a white dwarf and companion star, just like Sne Ia's. Of course, the current paradigm with dark energy rests almost exclusively on the observation that, as Goldsmith put it, "The cosmological constant's claim to a nonzero value fundamentally rests on the finding that distant Type Ia supernovae reach maximum brightnesses approximately 25 percent fainter than the peak brightnesses they would attain in a universe with a cosmological constant equal to zero." We certainly wouldn't want to base our new world view on the misidentification of a new class of supernovas! I am confident, though, that our well-studied supernova hunters are no dummies, are much smarter than me, and they're amazingly clever in how they can shake out Nature's secrets. Distinguishing Ia's from Iax's may not be that hard. Apparently the Iax's leave a remnant of the white dwarf behind. And the elemental abundances might also be dispositive.

So instead of a Martin or an equally expensive Gibson, I decided to go with an Epiphone Masterbilt EF-500RA NS. Solid rosewood back and sides, solid sitka spruce top with natural satin finish, mahogany neck, rosewood fingerboard, abundant abalone inlay, bound neck and headstock, Grover 'old-style' 18:1 tuners, bone nut and bridge.... Made in 2010 - the last year Epiphone made them. Rare! You don't see these come up for sale very often. I had this sent down from a guy up in Anchorage.... Oh, It's a 000 style, not dreadnought, with a 1.75" nut - wider than the more typical 1.68" on dreads. Makes fingerpicking easier. Surprising how much difference that 1/16" makes....

Jerry
2014-Aug-07, 02:54 AM
Ya, I've never seen a researcher let empirical data get in the way of good theory. Seriously, the distant sample do have slightly shorter light curves (on average); and they tend to be bright in the UV, although I have not seen any correlative studies on local UV brightness and the distant sample.

New paper of Iax

http://arxiv.org/abs/1408.1089 A luminous, blue progenitor system for a type-Iax supernova

Shaula
2014-Aug-07, 04:28 AM
Ya, I've never seen a researcher let empirical data get in the way of good theory.
And I've never seen you let the content of a paper get in the way of your interpreting as more support for your ideas.

Essentially to make a significant difference the rate of these supernovae would need to increase nearly linearly with distance from us. Given that the proposed mechanisms for them is not really one that would appear to be any more likely in the past this seems unlikely.

Jerry
2014-Aug-07, 09:23 AM
And I've never seen you let the content of a paper get in the way of your interpreting as more support for your ideas.

Essentially to make a significant difference the rate of these supernovae would need to increase nearly linearly with distance from us. Given that the proposed mechanisms for them is not really one that would appear to be any more likely in the past this seems unlikely.
These are not the supernova events that are most likely contaminating the redshifted sample, quite the opposite, selection effects favor contamination by overly brilliant events, not the whimpy ones.

http://arxiv.org/abs/1303.0580 A Redshift Dependent Color-Luminosity Relation in Type 1a Supernovae


A positive value of beta would increase the redder-is-dimmer corrections with increasing z-shift (distance), as expected from increasing dust. Instead, we find beta < 0 a decreasing color correction and the opposite effect, which is not expected and not attributable to conventional dust. The color-redshift is consistent with evolution of intrinsic luminosity or sources.

The distribution appears to flatten-out at higher redshifts - virtually no over luminous events. Either the sample is evolving, or we don't understand what we are seeing.

Jerry
2014-Aug-08, 12:12 AM
Type Ia Supernova Hubble Residuals and Host-Galaxy Properties http://arxiv.org/abs/1401.3352 I post this paper, because it also highlights the "Hubble residuals", which are also apparent distance bias indice that we cannot seem to null out.



http://arxiv.org/pdf/1309.1182v2.pdf Evidence of Environmental Dependencies of Type Ia Supernovae from the Nearby Supernova Factory indicated by Local Hα Same time of Hubble residuals.

Hlafordlaes
2014-Aug-08, 10:15 AM
I just want to thank Cougar for mixing supernovae with a guitar discussion. Plucky! That's what makes CQ a unique place.

[I don't get the connection, unless string theory is being backdoored. ;)]

Cougar
2014-Aug-09, 01:11 PM
[I don't get the connection, unless string theory is being backdoored. ;)]

Haha, yeah, the connection is pretty tenuous - just the fact that they added the letter "X" to the end of the prior designation. I'm pretty jazzed about my new guitar, though. :D

publiusr
2014-Aug-09, 05:02 PM
Just don't let stay near a standard candle--bad on the varnish, that smoke....

danscope
2014-Aug-09, 05:38 PM
Hi Cougar, Yes, the extra width is welcomed, especially when you want to play a clean chord without accidently dampening an adjacent string. The more complex chords and music need better, careful technique , and the neck really helps.
Clear skies and happy picking.
Dan

Jerry
2014-Aug-09, 05:44 PM
Just don't let stay near a standard candle--bad on the varnish, that smoke....
Very interesting. I was just reading about lighthouses; and how important it was to keep all of the windows and lenses clean. Ships depended upon the uniform light to judge distances from the coast at night; especially during times of high seas, which often lead a storm, making it difficult to triangulate. I have had a similar experience closing too fast on a car or pickup in a fog with weak or dirty tail lights.

The most distant sample could be dominated by this X-class of overluminous-in-the-blue and under-luminous-in-the-red supernova; or it could be the over-luminous-in-all bands class, (sometimes called hypernova.) What is known is that the most distant events we observe tend to be bluer and have slightly shorter light curves, (after correction for relativistic effects.) If they are X-class, the evidence of universal acceleration disappears. If they are over-brilliant; ( selection effects predict they should be) then the shortened light curves are troubling. In either case, the bluing of the distant sample should put cosmic parameters on hold until we better sort this out: Evolved supernova, or a systemic failure in the data reduction?

Oh, and the guitar thing? This ties to supernova quite well: Are you stringing with lots of metal, nylon or gut?