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- From: dwells@fits.cv.nrao.edu (Don Wells)
- Subject: Re: B-O Effect (was Re: Proof of quasar non-locality?)
- In-Reply-To: metares@well.sf.ca.us's message of Sun, 9 Aug 1992 20: 31:56 GMT
- Message-ID: <DWELLS.92Aug22001037@fits.cv.nrao.edu>
- Sender: news@nrao.edu
- Organization: nrao
- References: <DWELLS.92Jul20230959@fits.cv.nrao.edu> <Bs0L2J.Lr4@well.sf.ca.us>
- <DWELLS.92Jul31224122@fits.cv.nrao.edu> <BsqH18.7Hy@well.sf.ca.us>
- Date: Sat, 22 Aug 1992 05:10:37 GMT
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-
- [I have been on vacation for the past two weeks]
-
- In article <BsqH18.7Hy@well.sf.ca.us> metares@well.sf.ca.us (Tom Van
- Flandern) writes:
- dwells@fits.cv.nrao.edu (Don Wells) writes:
- > ... [the B-O Effect] .. tells us that the Universe..
- > has evolved.. [which] implies that there was a creation..
-
- TVF> .. Your objection is that the universe at high *galaxy* redshift
- TVF> looks different than the universe at low *galaxy* redshift,
- TVF> implying considerable evolution within a relatively short time..
- TVF> such rapid evolution would be a big surprise for the Big Bang
- TVF> theory too, where it must also be assimilated ex post facto. So
- TVF> I do not describe your well-taken objection as support for the
- TVF> standard model.
-
- I agree that the B-O Effect should not be regarded as support for the
- standard model, but it also is not inconsistent with it.
-
- TVF> ... yours is the most serious objection posed to the Meta Model
- TVF> in the discussion so far. Such a vast change of form for our
- TVF> local large scale universe would be unexpected unless all
- TVF> visible matter were undergoing some sort of change.. what I
- TVF> think is going on is that we have [an] extension of the blue
- TVF> giant branch.. into the ultraviolet, which would be not so
- TVF> easily observable through our atmosphere.. when.. galaxies are
- TVF> farther away, the ultraviolet extension shifts into the visible
- TVF> range, making the net color blue.
-
- You are describing the technicality which is traditionally called the
- "K-Correction" in observational cosmology: it corrects broadband
- magnitudes and colors back to the rest frame. In a prior posting, I
- described a spectrum of a B-O "blue" galaxy. The x-axis of that plot
- was wavelength *in the rest frame*, i.e. it does not suffer from this
- technical problem. A plot of any nearby object with the same type of
- spectrum would look just the same. Therefore, the blue broadband color
- of the distant (B-O) object cannot be due to a putative UV flux which
- would be hidden in nearby objects.
-
- This particular spectrum is similar to integrated spectra of nearby
- "late" spiral and irregular galaxies; I myself have measured
- integrated spectra of such objects. The term "blue" as used in the B-O
- context apparently has caused you to get the impression that the B-O
- galaxies in the distant clusters have unusual spectra with strong UV
- emission. In fact, such galaxies have relatively little emission in
- the UV (check the cited spectrum). The B-O galaxies---just like nearby
- "late-type" galaxies---simply contain some hot, young B and A stars
- and associated H-II regions, in addition to the usual population of
- cooler, older stars. The hot stars and emission lines imply recent
- star formation.
-
- -*-
-
- Recently I received a relevant preprint: "High Resolution Imaging of
- Distant Clusters: I. Close Pairs, Interactions and the
- 'Butcher-Oemler' Effect at Z=0.4", R.J.Lavery (Dept. Terrestrial
- Magnetism, Carnegie Inst. Washington, 5241 Broad Branch Rd. NW,
- Washington, DC 20008) and M.J. Pierce and R.D.McClure. The
- conclusions section of the paper says: "New, high-resolution images
- (FWHM=0.45 arcsec) of the blue galaxies in A370 and Cl0024+1654 have
- been presented. These images reveal that a significant fraction of
- these galaxies are multiple systems, unresolved by previous
- ground-based observations. In addition, a number of these systems show
- signs of significant morphological peculiarities, suggestive of
- interactions/mergers. These new data provide support for the mechanism
- of galaxy-galaxy interactions/mergers as being responsible for the the
- intense star formation occurring in these blue galaxies... it would
- appear that the Butcher-Oemler effect is primarily produced by
- interacting/merging disk galaxies undergoing starbursts. These results
- imply that interactions and mergers of gas-rich systems play an
- important role in the evolution of rich clusters from z~0.5 to the
- present epoch."
- --
-
- Donald C. Wells Associate Scientist dwells@nrao.edu
- National Radio Astronomy Observatory +1-804-296-0277
- 520 Edgemont Road Fax= +1-804-296-0278
- Charlottesville, Virginia 22903-2475 USA 78:31.1W, 38:02.2N
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