Jenn's Astronomy Project- Images and Analysis (16.280)

Jenn's 16.280 Project My Images

All images are processed, combined and scaled and are presented with North up and West to the right

Images taken through the Clear filter

Best Linear Display
Contrast= 1
Bias= .05
(In SAOimage contrast ranges from 0-10 and bias from 0-1)
Chosen to get the best overall idea of the galaxies

Bright Regions (Linear)
Contrast= 7.6
Bias=0.38
This image was displayed to show the detail in the bright areas. There really wasn't any detail to be seen in the bulges of either galaxy and so I chose to show how the bulge spirals out slightly into the arms and to show the bright region in the extended arm of UGC01810, the larger, face-on galaxy.

Faint Regions (Linear)
Contrast= 10.0
Bias= 0.38
This was manipulated to give the best idea of the faint regions of the galaxies. We can see in UGC01810 (the larger galaxy) that the arm actually continues all the way around and that there is a 'hole' between the arm and the bulge that is as fiant as the background itself. It also shows the bridge between the two galaxies where the larger galaxy is pulling the stars in the smaller companion towards it.

Log
Contrast= 4.4
Bias= 0.88
I used imreplace for this image as the holes were dominating the darker grays and washing out the object. I replaced all points 1100 or less (about 3 sigma less than the background) with a value of 1100.

Contours
Displayed over the Linear image.
There are 8 levels from 71-200 (I think SAOimage contours use level of greys and not actual pixel values. I know there are 256 levels of greys but anything higher than 200 didn't look any different than 200)
The contours show some structure in the bulge of my galaxy that I just couldn't bring out by changing the contast and bias in any of my images. It also shows the 'hole' between the arm and the bulge in the larger galaxy as well as the shape of the bridge.

Colour
Contrast= 1.5
Bias= 0.63
This colour scheme is called sls. I liked it because it showed the different levels of brightness the most clearly (and it looks pretty too ;)
I shows the brighter regions down the arms of UGC01810 nicely and also show how the bulge seems to spiral slightly into the arms. It doesn't show alot of detail in UGC01813 except the warp but none of the colour schemes at any contrast and bias really did.

Images taken through the Blue filter

Best Linear Display
Contrast= 2.0
Bias= 0.71
As we can see even the best stretch in blue is really noisy. Our CCD is not very responsive to blue wavelengths.

Bright Regions (Linear)
Contrast= 10.0
Bias= 0.7
This image was displayed to show the detail in the bright areas. There really wasn't any detail to be seen in the bulges of either galaxy. This shows the bright region in the extended arm of UGC01810, though it doesn't stand out quite as clearly as in the clear image. It also shows a bright region to the East (left) of the bulge in in the smaller companion UGC01813. This appears again in the contours

Faint Regions (Linear)
Contrast= 5.5
Bias= 0.57

Log
Contrast= 9.7
Bias=0.94

Contours
Displayed over the Linear image
The 8 contour levels here were between 105 and 209.
Like these levels because they show the brighter region in the arm of the larger galaxy, UGC01810 (by the star on the West) and also an interesting feature in UGC01813, the smaller galaxy; there appears to be two bright regions near the center of the galaxy.
The feature in UGC01813 appears only in the blue (once I found it I re-cheacked the clear image and watched for it when doing the contours on the red) and so is potentially a concentration of young stars. If true, this would seem to support the theory brought up in some of the more recent papers about this pair which says there is a starburst happening in the smaller companion, UGC01813.
Starbursts caused by interactions don't necessarily start at the same time in both galaxies. In fact there can be up to 2x10⁸ years between starburst starting in the minor (smaller) galaxy and starburst starting in the major (larger) galaxy. Starburst tend to start in the smaller galaxies first. (Bernlohr, K. Astron. Astrophys. 268, 25-34, 1993)

Colour
Contrast= 1.4
Bias= 0.7
This colour scheme is called aipso and is mostly included to show how little structure can be seen in the blue image. There is more dfinition in the noise than in the objects (I unfortunately couldn't find a colour scheme or contrast and bias setting that could bring out the second bright region in UGC01813 and not have the noise in the background be overpowering.

Images taken through the Red filter

Best Linear Display
Contrast= 1.7
Bias= 0.5
Chosen to get the best overall idea of the galaxies

Bright Regions (Linear)
Contrast= 4.8
Bias= 0.66
The bulge of the larger galaxy, UGC01810, simply went to a round dot and so I chose to show the detail in UGC01813, the smaller galaxy and how the one half is brighter in the red than the other.

Faint Regions (Linear)
Contrast= 7.7
Bias= 0.38

Log
Contrast= 6.4
Bias= 0.89

Contours
Displayed over 9 levels between 60-150
There really wasn't any details to see above a value of 150. The structure that was seen in the clear image isn't apparant here, the bulge is simply circular.

Colour
Contrast= 1.5
Bias= 0.65
This colour scheme is sls. It shows fairly little interesting detail in UGC01810 but this is significant because that means the brighter region in the arm seen in the clear image is due to blue light only as it was seen in the blue contours but not here in the red. It also shows that the West side of UGC01813 is brighter in the red than the East side, something that was only slightly apparent in the clear image This would lead me to believe that there are more young blue stars (or middle age green/visual stars) on the East side than older red ones to help balance the overall brighness in the clear image. Could this be taken as another indication of star formation or recently past star formation?

Back

Best Linear Display Contrast= 1 Bias= .05 (In SAOimage contrast ranges from 0-10 and bias from 0-1) Chosen to get the best overall idea of the galaxies
Bright Regions (Linear) Contrast= 7.6 Bias=0.38 This image was displayed to show the detail in the bright areas. There really wasn't any detail to be seen in the bulges of either galaxy and so I chose to show how the bulge spirals out slightly into the arms and to show the bright region in the extended arm of UGC01810, the larger, face-on galaxy.
Faint Regions (Linear) Contrast= 10.0 Bias= 0.38 This was manipulated to give the best idea of the faint regions of the galaxies. We can see in UGC01810 (the larger galaxy) that the arm actually continues all the way around and that there is a 'hole' between the arm and the bulge that is as fiant as the background itself. It also shows the bridge between the two galaxies where the larger galaxy is pulling the stars in the smaller companion towards it.
Log Contrast= 4.4 Bias= 0.88 I used imreplace for this image as the holes were dominating the darker grays and washing out the object. I replaced all points 1100 or less (about 3 sigma less than the background) with a value of 1100.
Contours Displayed over the Linear image. There are 8 levels from 71-200 (I think SAOimage contours use level of greys and not actual pixel values. I know there are 256 levels of greys but anything higher than 200 didn't look any different than 200) The contours show some structure in the bulge of my galaxy that I just couldn't bring out by changing the contast and bias in any of my images. It also shows the 'hole' between the arm and the bulge in the larger galaxy as well as the shape of the bridge.
Colour Contrast= 1.5 Bias= 0.63 This colour scheme is called sls. I liked it because it showed the different levels of brightness the most clearly (and it looks pretty too ;) I shows the brighter regions down the arms of UGC01810 nicely and also show how the bulge seems to spiral slightly into the arms. It doesn't show alot of detail in UGC01813 except the warp but none of the colour schemes at any contrast and bias really did.

Best Linear Display Contrast= 2.0 Bias= 0.71 As we can see even the best stretch in blue is really noisy. Our CCD is not very responsive to blue wavelengths.
Bright Regions (Linear) Contrast= 10.0 Bias= 0.7 This image was displayed to show the detail in the bright areas. There really wasn't any detail to be seen in the bulges of either galaxy. This shows the bright region in the extended arm of UGC01810, though it doesn't stand out quite as clearly as in the clear image. It also shows a bright region to the East (left) of the bulge in in the smaller companion UGC01813. This appears again in the contours
Faint Regions (Linear) Contrast= 5.5 Bias= 0.57
Log Contrast= 9.7 Bias=0.94
Contours Displayed over the Linear image The 8 contour levels here were between 105 and 209. Like these levels because they show the brighter region in the arm of the larger galaxy, UGC01810 (by the star on the West) and also an interesting feature in UGC01813, the smaller galaxy; there appears to be two bright regions near the center of the galaxy. The feature in UGC01813 appears only in the blue (once I found it I re-cheacked the clear image and watched for it when doing the contours on the red) and so is potentially a concentration of young stars. If true, this would seem to support the theory brought up in some of the more recent papers about this pair which says there is a starburst happening in the smaller companion, UGC01813. Starbursts caused by interactions don't necessarily start at the same time in both galaxies. In fact there can be up to 2x10⁸ years between starburst starting in the minor (smaller) galaxy and starburst starting in the major (larger) galaxy. Starburst tend to start in the smaller galaxies first. (Bernlohr, K. Astron. Astrophys. 268, 25-34, 1993)
Colour Contrast= 1.4 Bias= 0.7 This colour scheme is called aipso and is mostly included to show how little structure can be seen in the blue image. There is more dfinition in the noise than in the objects (I unfortunately couldn't find a colour scheme or contrast and bias setting that could bring out the second bright region in UGC01813 and not have the noise in the background be overpowering.

Best Linear Display Contrast= 1.7 Bias= 0.5 Chosen to get the best overall idea of the galaxies
Bright Regions (Linear) Contrast= 4.8 Bias= 0.66 The bulge of the larger galaxy, UGC01810, simply went to a round dot and so I chose to show the detail in UGC01813, the smaller galaxy and how the one half is brighter in the red than the other.
Faint Regions (Linear) Contrast= 7.7 Bias= 0.38
Log Contrast= 6.4 Bias= 0.89
Contours Displayed over 9 levels between 60-150 There really wasn't any details to see above a value of 150. The structure that was seen in the clear image isn't apparant here, the bulge is simply circular.
Colour Contrast= 1.5 Bias= 0.65 This colour scheme is sls. It shows fairly little interesting detail in UGC01810 but this is significant because that means the brighter region in the arm seen in the clear image is due to blue light only as it was seen in the blue contours but not here in the red. It also shows that the West side of UGC01813 is brighter in the red than the East side, something that was only slightly apparent in the clear image This would lead me to believe that there are more young blue stars (or middle age green/visual stars) on the East side than older red ones to help balance the overall brighness in the clear image. Could this be taken as another indication of star formation or recently past star formation?