Messier 82 (NGC 3034)

Observatory / Course Archives / ASTR 212 Spring 2019 / Williams

Messier 82 , also known as NGC 3034 (seen above) is in the constellation Ursa Major and classified as an IO starburst galaxy. A starburst galaxy is a galaxy undergoing high rates of star formation. Its nicknamed the "Cigar galaxy" due to its firey imaging in the infrared wave length. It was first discovered by Johann Elert Bode in 1774 alongside its neighboring galaxy M81. M82 is located around 12 million light years from earth and is roughly 37 thousand light years in diameter. It used to be a spiral galaxy much like the milky way; but through strong gravitational interactions with other galaxies, has lost its spiral structure. This interaction also led to the mixing of gases and dust which is why there is such heavy star formation.

New stars in a galaxy are big and hot. They give off a blue color which can be seen around the edges of the galaxy. The center of the galaxy is redder due to older stars, which give off a red/yellow color, and the massive amounts of dust. The dust scatters the blue light but allows the redder light to pass through. This same scattering is how we get a blue sky during the day time, and red sky during sun set.

What else can we tell from this picture? Well, given the distance from earth to M82 in Mpc, we are able to find its diameter and compare to see if it matches! We first take the semi-major and major axis of the picture in terms of pixels (from our image). We then convert this to arc-seconds. Finally, using the distance, angular size, and the small angle formula we can determine the size of our object in light years. \theta =\frac{l}{d} where \theta is the angular size in radians, {l} is the physical size, and {d} is the distance. {l} =(.0024radians)*(1.35e7light years) = 32,400 ly which is close to the actual size of roguhly 37,000!

Non-optical cross-comparison:

Here (in the second image) we have is M82 observed in the x-ray spectrum. What astronomers thought was a block hole turned out to be the brightest pulsar ever recorded.

In the third image, we get an overlay of the x-ray imaging on top of the optical imaging. We can see that the source is at the galactic center. Knowing that super massive black holes are at the center of most galaxies, astronomers thought that matter falling into the black hole was the cause of the x-ray emmissions. As it turns out, the pulsation period of this object doesn't line up with those of black holes, but rather, rapidly rotating neutron stars.

The fourth image is an infrared view of M82. The (red) dust particles are being thrown out into space by the newly forming stars. The spectrograph of the dust contains a carbon-containing coumpound which can be found here on Earth in tailpipes, BBQ pits, and other places where combustion reactions occur.

The last image is taken in the radio wave spectrum by the Very Large Array. It shows a massive amount of star formation. These are shown as the bright points in the picture.

References:

Frommer, Hartmut. "Messier 82" Students for the Exploration and Development of Space. <www.messier.seds.org/m/m082.html>.

Wikipedia, "Messier 82".

NASA/IPAC Extragalactic Database "MESSIER 082" <ned.ipac.caltech.edu>

Right Ascension (J2000)	09:55:54
Declination (J2000)	69:40:47
Filters used	B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter	B(240s); V,R,C (120s)
Image dimension	473x329 pixels; 10.25x7.13 arcminutes
Date/time observed	March 18, 2019, 02:54 UT

In order to get our image, we have to reduce the data given to us by rehoboth. Reducing data refers to the process of taking the raw data and processing it to remove the effects of CCD bias, thermal noise, and nonuniform CCD sensitivity/illumination. First, visually inspect all of your calibration frames one set at a time. Open MaxIm, then 1. Highlight and drag all of the bias frames into MaxIm. 2. Go to the View menu and select Animate. 3. In the window that appears, click ‘Add All’, then OK, and then in the small control window that appears click the Play button and watch the movie. 4. Compare each to a typical bias frame shown above. If you see something that differs significantly from the image below, do not use it. Repeat the steps above for the darks and flats as well. For the flats scan through them one filter at a time. Create a Master Bias Start by closing all open images in MaxIm. Go to the Process menu and choose Stack. (a) In the Select tab, click Add Files and navigate to the directory that contains your biases. Select all of them, then click Open. (b) In the Combine tab, set Combine Method to Median. (c) In the Combine tab, set FITS Format to 16-bit Int. (d) In the Combine tab, set Normalization to None. (e) Click Go. Inspect the stacked bias frame that appears. Save the result as “Master Bias.fit” or something equally memorable. Verify that the settings are 16-bit Int format, Manual Stretch, and Uncompressed before clicking Save. Remember to save it in the “Calibration Files” folder. Then close it in MaxIm. Create a Master Dark, go to the Process menu and choose Stack. (a) In the Select tab, if a folder is visible in the window on the left side of the pop-up window, right-click on it and select Remove Item. (b) In the Select tab, click Add Files and navigate to the directory that contains your darks. Select all of them, then click Open. (c) In the Combine tab, set Combine Method to Median. (d) In the Combine tab, set FITS Format to 16-bit Int. (e) In the Combine tab, set Normalization to None. (f) Click Go.Inspect the stacked dark frame that appears. It should look similar to the individual darks. Save the result as “Master Dark.fit” or something equally memorable. Verify that the settings are 16-bit Int format, Manual Stretch, and Uncompressed before clicking Save. Remember to save it in the “Calibration Files” folder. Then close it in MaxIm. Create Master Flats In the Process menu, choose Set Calibration. In the window that appears: (a) Beneath the big white window in the center, on the left, is a drop-down menu. Set this to BIAS and click Add Group. (b) Click the Add button at the bottom-right portion of the window and select the Master Bias image you created in Section D.2. (c) Now set the drop-down menu to DARK and click Add Group. (d) Click the Add button at the bottom-right and select the Master Dark image you created in Section D.3. (e) With the DARK item highlighted in the big white window, set the “Dark Frame Scaling” menu to Auto-Scale. (f) Click OK. In the File menu, choose “Batch Save and Convert”. (a) Click Select Files, navigate to where your flats are held, select them all, and click Open. (b) Outside of MaxIm, create a new directory where you would like the calibrated flats to be held. (c) In MaxIm once again, click Path and navigate to that directory you just made. (d) Check the “Perform Calibration” box. (e) Verify the settings: File Format = FITS, Size Format = 16-bit INT, Auto Stretch = None, Compression Type = Uncompressed. (f) Click OK. Open only the calibrated flat frames for ONE PARTICULAR FILTER in MaxIm. This process should be done one filter at a time. In the Process menu, select Stack. (a) In the Select tab, if a folder is visible in the window on the left side of the pop-up window, right-click on it and select Remove Item. (b) In the Select tab, click Add Images (if not visible, this may be found by clicking the down arrow next to Add Files) and choose Add All. Click OK to close the tiny window. (c) In the Combine tab, set Combine Method to Median. (d) In the Combine tab, set FITS Format to 16-bit Int. (e) In the Combine tab, set Normalization to Linear, and set Area to 90. (f) Click Go. Inspect the stacked flat frame that appears. Save the result as “Master Flat x.fit” or something equally memorable, where ‘x’ is the filter label. Verify that the settings are 16-bit Int format, Manual Stretch, and Uncompressed before clicking Save. Remember to save it in the “Calibration Files” folder. Close all of the open flat field frames by going to the File menu and selecting Close All. Then repeat this process (previous Stack steps 1–3) with the other filters for which you have flats and data. Reduce Data Frames First, in MaxIm open all the data frames and visually inspect them using View+Animate as you did previously.Go to the View menu and select Animate. In the window that appears, click ‘Add All’. In the small control window that appears, set the timing menu to 0.5 sec or 1 sec, then click the Play button and watch the movie. You will see your star field move around with respect to the bright pixels that have not yet been calibrated out. You are first looking to see if any images are obviously affected by clouds or other bad lighting conditions that cannot be fixed. If you see these, close them and make a note about which ones these are. Go to the Process menu and choose Set Calibration. In the window that appears: (a) Beneath the big white window in the center, on the left, is a drop-down menu. Set this to FLAT and click Add Group. Leave the BIAS and DARK groups in there. (b) Click the Add button at the bottom-right portion of the window and select one of the Master Flat images you created in Section D.4 for that filter. (c) In the white window in the center beneath the Calibration Groups heading, click in the space in the Filter column for the FLAT group you just added. Type in the letter that corresponds to your filter (or “Clear” for the unfiltered flat). (d) Repeat the previous two steps for every filter you have. (e) Click on the Dark group and set the Dark Frame Scaling menu to Auto-Optimize. (f) Click OK to close the window. From the File menu, choose “Batch Save and Convert”. (a) Click Select Files, navigate to where your data frames are held, select them all, and click Open. (b) As you did with flats, outside of MaxIm, create a new directory where you would like the calibrated data frames to be held. (c) In MaxIm once again, click Path and navigate to that directory you just made. (d) Check the “Perform Calibration” box. (e) Verify the settings: File Format = FITS, Size Format = 16-bit INT, Auto Stretch = None, Compression Type = Uncompressed. (f) Click OK. 3. Open the calibrated images and repeat the View+Animate again and look for more images that are affected by clouds which may have passed your first inspection. If you find any, move them to the “Omitted” folder. You may also omit any that are obviously out of focus or that have very poor seeing. When going to the Final data Image Processing I did Red: 1 Green: 1 Blue: 5 with the Luminance weight at 50%. I then choose the saturation level to be 130%.