Re: [Utah-astronomy] M22's Blue Stars (continued)
There is a long sad story that goes with this debate. Several years ago when astrophotography was starting to catch on in amateur circles there was a vigorous debate about whether pictures should reflect reality of the science or be interpreted solely for their beauty. The science side held the moral high ground but over time were swamped by events in the market place. The software vendors have no sympathy with scienctific realism and they install auto whitebalance routines all along the chain of processing. Starting with antiblooming gain on the chip and the color masks of popular DSLR cameras through the conversion to JPEG and into the world of photoshop. It is extremely difficult to get an accurate color balance with amateur equiptment. When it is achieved with much effort and special equiptment the results are less "pretty" than most people want to see. For the science, we know the color of M22 by brute force analysis of individual stars. lots of them. There are no vast populations of blue stars in the cluster. http://www.slas.us/gallery2/main.php?g2_itemId=2033 We know where the mainsequence cutoff is, it is redish, and you can see the spinkle of blue stragglers to the left of that. This is the reality of M22, the science. DT
Check out this schematic of M30, the red and blue dots need no explanation. The white dots are white dwarfs and green dots are horizontal branch stars. M 30 is out of the disk (Capricorn), so I wonder if you can say M22 would have a bigger population of blue stars. http://www.sns.ias.edu/~jnb/HST/Globclusters/m30.gif
There is a long sad story that goes with this debate. Several years ago when astrophotography was starting to catch on in amateur circles there was a vigorous debate about whether pictures should reflect reality of the science or be interpreted solely for their beauty. The science side held the moral high ground but over time were swamped by events in the market place. The software vendors have no sympathy with scienctific realism and they install auto whitebalance routines all along the chain of processing. Starting with antiblooming gain on the chip and the color masks of popular DSLR cameras through the conversion to JPEG and into the world of photoshop. It is extremely difficult to get an accurate color balance with amateur equiptment. When it is achieved with much effort and special equiptment the results are less "pretty" than most people want to see. For the science, we know the color of M22 by brute force analysis of individual stars. lots of them. There are no vast populations of blue stars in the cluster.
http://www.slas.us/gallery2/main.php?g2_itemId=2033
We know where the mainsequence cutoff is, it is redish, and you can see the spinkle of blue stragglers to the left of that.
This is the reality of M22, the science.
DT
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
You will notice the blue stragglers are brighter than the most of the other stars and their numbers are significant in the brighter magnitude ranges. If you cut off the diagram at about 16th magnitude you will see what an amateur CCD image will probably show since amateur exposures of globulars are typically many stacked images of short exposures. With such a cutoff the blue stars will show a much higher density than is actually the case. -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of daniel turner Sent: Saturday, June 13, 2009 1:21 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] M22's Blue Stars (continued) There is a long sad story that goes with this debate. Several years ago when astrophotography was starting to catch on in amateur circles there was a vigorous debate about whether pictures should reflect reality of the science or be interpreted solely for their beauty. The science side held the moral high ground but over time were swamped by events in the market place. The software vendors have no sympathy with scienctific realism and they install auto whitebalance routines all along the chain of processing. Starting with antiblooming gain on the chip and the color masks of popular DSLR cameras through the conversion to JPEG and into the world of photoshop. It is extremely difficult to get an accurate color balance with amateur equiptment. When it is achieved with much effort and special equiptment the results are less "pretty" than most people want to see. For the science, we know the color of M22 by brute force analysis of individual stars. lots of them. There are no vast populations of blue stars in the cluster. http://www.slas.us/gallery2/main.php?g2_itemId=2033 We know where the mainsequence cutoff is, it is redish, and you can see the spinkle of blue stragglers to the left of that. This is the reality of M22, the science. DT _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
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