At what temperature is the light in the B filter equal to the light in the R filter (i.e. the peak of the curves are the same height)? What is the lowest temperature at which U>B>V>R?
Which star is brighter in the B image? Which is brighter in the R image?
Send a screen shot of the 4 profiles to Chris Martin and post your analysis of which star is the hotter, A or B, on the blog.
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At a temperature of 5780K the B and R filter have the same size
ReplyDeleteAt the lowest temperature of 7810K U>B>V>R
In the R filter star B appears brighter
In the B filter star A appears brighter
R filter, star A, peak 22000
R filter, star B, peak 60000
B filter, star A, peak 11000
B filter, star B, peak, 8,000
It appears that star A has greater brightness than Star B in the blue region. It follows that star A is hotter than star B.
It was tough to determine max curve height, but at a temperature of 5730K the B and R filter appear to have the same size
ReplyDeleteAt the lowest temperature of 7520K the height of U>B>V>R
In the B filter both stars appear the same.
In the R filter star B appears brighter.
R filter, star A, peak 19811.6
R filter, star B, peak 61242.0
B filter, star A, peak 10520.1
B filter, star B, peak, 59517.4
It appears that star A has greater brightness than Star B using the blue filter – which allows the blue light through the best. It makes sense that star A is hotter than star B.
I spent the weekend at Kitt Peak observing, and on Friday night one of the Astrobits participants from the fall joined me. I wanted to remind all of you that this will be an invitation you will receive when you complete 6 modules. William ran the telescope and camera: I was there to help and answer questions. I dont' think I can post images here, but we have a lovely image of a distant galaxy called M 81: the image can be manipulated in Imagej.
ReplyDeleteMore later...
It appears that B = R at a temperature equal to 5730 K and U>B>V>R at T =7630 K.
ReplyDeleteI can say that A is brighter through the B filter and B is brighter with R.
A is slightly (~15%) brighter using the B filter, while B is around ~245%) brighter using the R filter
The peak in the B filter is the same as the peak in the R filter when T = 5720 K. This means the flux is the same at those points, but the amount of light at this temperature is not the same. The strength of the red filter is definitely higher in the little graphic at this temperature, which indicates there is more red light than blue light emitted from a star at this temperature. You can also see this visually by examining the area under the blackbody curve that corresponds with the R and B filters.
ReplyDeleteThe lowest temperature at which U >B >V>R is around 9710 Kelvin. In fact, all filters have the same magnitude at 2.7 when the temp is 9700 Kelvin which means that a star at this temperature is emitting the same amount of U, B, V, and R light.
In the star cluster M26, I guessed that star A is brighter in the B image and star B is brighter in the R image. Star A is hotter because it is brighter in the blue filter. According to Wien’s law, the shorter the peak wavelength, the hotter the star, so since star A appears bluer, it must be hotter. After using ImageJ to analyze the brightness of the two stars, I can conclude that star A is hotter because it is brighter in the blue filtered image.
The light in the B filter is equal to the light in the R filter around 5600K. The lowest temperature at which U>B>V>R is around 7600K.
ReplyDeleteI thought that star B looked brighter in both filters. But, my measurements showed that star B is brighter with an R filter and less bright in a B filter. Is gray value the way that astronomers measure brightness?
Star A must be hotter because it is brighter in the image taken with the blue filter.
The R filter will have the same peak as B filter at T = 5720K and the lowest temperature at which U>B>V>R is at T = 7610K.
ReplyDeleteWhen I did the profiling, it appears that star A is a little bit brighter than Star B using B filter and using R filter, Star B is brighter than Star A.
I conclude that Star B is hotter than Star A.
From John Webster
ReplyDeleteI got the temperature of 5730° K where the Blue and Red peaks were equal under the curve. The lowest temperature for the four filters was 9550° K with U at 2.78, B at 2.77, V at 2.76, and R at 2.75.
When I analyzed the images with the R filter, Image B was brighter than Image A. With the B filter, Image A was brighter than Image B. Since we saw that stars with more blue light are hotter, the B filter blocked more of Image B’s blue light allowing A to look brighter. More of A’s light was blocked by the R filter, allowing image B’s light to look brighter. This would appear to show that Image B has more blue light and is hotter.
In image R, star B definitely looks brighter than star A. But, in image B, both stars look exactly the same to me. When I did the quantification, the peak of star A in the b.fits image was about 12000 DM, while the peak of star B was about 8,000 DM. This contradicted the other image, where Star A had a peak around 20000, and Star B had a peak around 60000. Since this is a much more marked difference than in image b, where the values are virtually the same, it’s more reliable. So, star B is hotter.
ReplyDeleteFrom 9680 K to 9720 K, the B & R filters have a color index of zero (they are the same brightness). The lowest temperature at which U>B>V>R was 9850 K.
ReplyDeleteStar A appears brighter in the B image, while star B appears brighter in the R image. The hardest part of doing this was finding the stars on the screen!!! Since B’s gray values are much higher in the red filter, it’s brighter in red. In the blue filter. B’s values are still slightly higher! If it's giving more energy in the blue image, I'll go with B being the hotter star. I think.
The temperature that I got where the peaks of B and R are equal under the curve is at 5740K. The lowest temperature for the four filters where U>B>V>R is at 9540 where U:2.79 > B:2.77 >V:2.76 > R:2.75.
ReplyDeleteI observed that in R filter, image B (DN 21668) is brighter than A (DN20488), using B filter image B is still brighter (DN6669.903) than image A (DN3608.7978). Based on this results Images on R filter appears brighter than B.
The temperature at which the peak of the blue filter is equal to the peak of red filter is T=5750K and the lowest temperature at which U>B>V>R is T =7620K
ReplyDeleteStar A is 10% brighter than in Star B in blue filter and Star B is 60% brighter than Star A in red filter. Using the color index formula and the simulator, the color index of Star A is 0.8 and its temperature is 5710K. The color index of Star B is 2.0 and its temperature is 3600K. This results show that Star A is hotter than Star B. This also explain why Star A is brighter than Star B in blue filter
The temperature that I found the light in the B filter equal to the light in the R filter was 5710 K. The lowest temperatures at which U>B>V>R appeared to be 7590.
ReplyDeleteWith just eye-balling it, in Image B, Star A appears brighter and in Image R, Star B appears a lot brighter.
Comparing the brightness of the stars using the Analyze/plot profile:
Image R shows Star B to be three times brighter than Star A
Image B shows Star A to be 1.5 times brighter than Star B
With this information it is easy to see that Star A appears more blue and Star B appears more red, therefore Star A is hotter.
The temperature at which the B & R values are the same is 5720K. And the temperature at which the values for U>B>V>R is 7630 K.
ReplyDeleteObserving the two stars from different filters, I would say that Star B is brighter than Star A.
Using analysis of their profiles: Star A is brighter in Blue filter and Star B is brighter in Red filter
Since Star A is brighter in blue filter, I conclude that Star A is hotter than Star B.
Ok, we are delighted to see you all keeping up with this project! On this assignment , if you read through all the posts, you will see there is a disagreement in the second part about which star is hotter, star A or star B. Here is what I measure: in the B (blue) filter, star A peaks at 10,000 counts and star B peaks at 8,000 counts. In the R (red) filter, star A peaks at 20,000 cts, and star B peaks at 58,000 cts. Remember, its the ratio of the blue filter to red filter that tells you about the relative temperture of a star...
ReplyDeleteAt approximately 6460 K the curve has a shape such that the ultraviolet light is on one side of the maximum peak and the red light is on the other side of the peak. These two look to have approximately the same magnitude at that temperature.
ReplyDeleteThe lowest temperature for which U > B > V > R appears to be 7,620 K or thereabouts. How about 7,620 + 200ish?
When I do an analysis of the two stars in the red image star A is brighter and in the blue image star B is brighter. I conclude that star B is hotter than star A.