A Picturebook of Very Red Stars (VRSs, Laura's Stars...)

Steve Bracker
September 7, 2005


A preliminary cut extracts from the Glimpse catalog only those stars having 
K - I8.0 > 3.0.  About 45,000 stars pass the cut; these are the VRSs.  
A VRS color-color plot is made: I3.6-I4.5 vs I3.6-I8.0.  See 01 below.

VRSs populate four regions in color-color space; each region is assigned a 
plotting color for the annotated images that follow:
1. lower peak (green)
2. upper peak (blue)
3. northeast fan, extending red-redwards of upper peak (yellow)
4. northwest fan, extending upwards close to I3.6 = I4.5 (magenta)
Some VRSs fall outside all regions and are not plotted. 

There are two color-color region definitions for each region:
1. Inclusive, which captures most of the stars in the region at the expense of 
including a significant number of interlopers as well. Inclusive regions do 
not overlap other inclusive regions, however.
2. Exclusive, which excludes most interlopers at the expense of missing a 
significant number of stars properly within the region. All exclusive regions 
are proper subsets of the corresponding inclusive region. See 02 below.

All images are jpeg files produced using DS9. All coordinates superimposed on 
the images are galactic. The picturebook images are 
/usr/users/ebc/bracker/redStars/pictbookNN.jpg   where NN is the picturebook 
image number 01, 02....

For color images, the association between rendered color and band:
red -- I8.0 (band 4)
green -- I5.8 (band 3)
blue -- I3.6 (band 1)
Single-band images are often rendered in black and white (b/w).


 

01--
Color-color plot of all VRSs; a few points are outside the plot bounds


 

02--
The color-color regions -- lower peak, upper peak, NE fan and NW fan.  The 
inclusive (larger) and exclusive (smaller) regions are shown.


 

03--
Overview: 8x2 degree mosaic, I8.0 band b/w, galactic coordinates, no VRSs 
plotted. (Compare to 04 and 05)


 

04--
Same as 01, with inclusive VRS positions superimposed. The lower-peak stars 
are strongly associated with IR dark clouds.  The rest are much more 
homogeneously distributed, though there is some clumping of upper-peak stars 
as well. (Compare to 03 and 05)


 

05--
Same as 02, with image suppressed. (Compare to 03 and 04)


 

06--
Same as 04, but with exclusive VRS positions superimposed instead. There 
seems to be a minor but robust clumpiness to upper-peak VRSs.


 

07--
Same as 06, with image suppressed.


 

08--
Color image of a small region near l=10.8.  There are several prominent dark 
clouds. No VRSs plotted; compare to 09.


 

09--
Same as 08, with lower peak (green) and upper peak (blue) VRSs superimposed. 
The association of the lower-peak VRSs with the dark clouds is clear.


 

10--
Magnified view of a portion of 09.


 

11--
Magnified view of another portion of 09.


 

12--
Another extensive area having dense black clouds near l=12.9. Note that the 
dark clouds extend into the next mosaic (below). No VRSs are plotted here; 
compare to 13.


 

13--
Same as 12, but with lower and upper peak VRSs superimposed.


 

14--
The extension of 13 to higher longitude (next mosaic). 


 

15--
The "Question Mark Cloud" near l=14.2. No VRSs are plotted.


 

16--
Lower and upper peak VRSs near the Question Mark Cloud.


 

17--
A complex region of dark clouds and bright emission near l=23.5.  No VRSs 
plotted; compare to 18.


 

18--
VRSs (lower and upper peak) near l=23.5.  Here the association of VRS clumps 
to dark clouds, though still apparent, is confused by intervening luminous 
material. It is helpful to have diffuse emission behind the dark cloud to 
silhouette it, but not helpful to have emission in front hiding it.