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Messier 38 (NGC 1912)

Thomas W. Brown

M38

Messier 38 or NGC 1912 is an open cluster in the Auriga constellation. It was first noted as a cluster by Giovanni Batista Hodierna before 1654. It is grouped with M36 and M37 at a distance of about 3440 ly (+/- 40 ly). M38 cannot be seen by the naked eye, but is bright enough to be visible through most binoculars. Open clusters are usually loosely bound groups of stars. This cluster is known for its (usually upside-down) loose π shaped cluster of bright stars at its center. The image shown does not account for the entire cluster, as it is too large for Calvin College’s Rehoboth camera, but, instead, accounts for the core cluster of stars.

For a full photo of the object please visit the Sloan Digital Sky Survey here - http://www.wikisky.org/?object=Messier+38&img_source=DSS2.

HR-Diagram Analysis:

An HR-Diagram analysis was also undertaken on this star cluster using the above photo. An HR-Diagram analysis is useful for telling the types of stars that are in a system and the age of those stars. This can be done by comparing to the Main Sequence shown below. Most stars will fall on this sequence with the more massive stars in the top left, the lowest mass ones in the bottom right. Our own star, Sol, can be found at G2. This image was taken from the Department of Astronomy from Mount Holyoke College.

hrdiagram

By splitting up the image taken of Messier 38 into nine quadrants and cataloging the brightness of the 197 brightest stars in the image an HR-Diagram could be made. The brightness of each star was calibrated using the three brightest. These are the three large stars in the middle left of the above image. Each object was located in the Blue filter and the Visible filter to two values that could be graphed and compared to other HR diagrams of this cluster. The image below is of the results of the data taken in this survey.

bvimage

It is easily seen that the majority of the stars graphed fall on a negatively sloped line from the top left corner to the bottom middle. This corresponds to the Main Sequence of stars. Stars that do not fall on this sequence are most likely foreground or background stars. As stars leave the Main Sequence they will curve upward towards the top right corner before dying in a Supernova.

The image below is another HR diagram of Messier 38, taken by astronomers from the Aryabhatta Research Institute of Observational Sciences, which can be compared to the above diagram. It can be noted that the shape is similar even if the below image contains more stars from the cluster. CMD stands for Color Magnitude Diagram and NGC 1912 is the other name for Messier 38 (Stellar Contents).

cmd

 

Image Processing:

The image was manipulated to change the initial, colorless photos into the final image above. The photos had to be colored, combined and then modified to bring out the actual colors. The photos were first manipulated using the Bias, Dark, and Flat photos taken the night of the observations. Once these took out all the 'noise' in the image that was not supposed to be there, the photos were combined by stacking them using the Sigma Clip method. Once this was done for all 4 filters, the photos were combined into a single color image of luminance weight 10%. The color sensitivity matrix was manipulated to bring out the accurate colors and can be seen in the table below. Next the image bleeding and bloom were removed to prevent these from obscuring the photo. Finally, the color saturation and the brightness scale were adjusted to give the photo the proper color spectrum. The results can be seen at the top of this page.

Red 2 - -
Green - 1.5 -
Blue - - 8

Infrared:


M38infrared

This is an infrared image of open cluster M38 in Auriga. This image was created from photographic data obtained with the 2MASS infrared telescopes. False colors were used to map different IR wavelength bands. The size of the infrared stars lines up perfectly with the size of the stars in the visible wavelength image taken by Calvin's Rehoboth telescope.

For more information see http://messier.seds.org/more/m038_more.html

References:

Espenak, Fred. "M38." AstroPixels. N.p., 28 June 2011. Web. 20 Apr. 2015. http://astropixels.com/openclusters/M38-01.html

"Messier 38 – M38 - Open Cluster." freestarcharts.com. N.p., n.d. Web. 20 Apr. 2015. http://www.universetoday.com/34302/messier-38/

Plotner, Tammy. "Messier 38." Universe Today. N.p., 6 July 2009. Web. 20 Apr. 2015. http://freestarcharts.com/20-guides/messier/144-messier-38-m38-open-cluster

"Stellar Contents of Two Intermediate Age Clusters." Oxford Journals. N.p., n.d. Web. 4 May 2015. <http://pasj.oxfordjournals.org/content/59/3/547.full.pdf+html>.

 

Data Label

Value Unit
Messier 38 N/A

NGC

1912 N/A

Collinder

67 N/A

Right Ascension (J2000)

05:28:42.00 Hr/Min/S

Declination (J2000)

+35:51:18.0 °/Min/S

Magnitude

7.4 N/A

Apparent Size

21x21 arcmin

Radius

25 ly

Stars

~100 N/A

Object Type

Open Cluster N/A

Observing Location

Rehoboth-, NM, USA, Earth (Terra) N/A

Observer

Controlled Remotely Programmed

Image Processor

Thomas Brown Human

Filters Used

Clear B V R Unit

Time Length (Each Exposure)

60 60 60 60 s
Exposures 2 50 12 12 #

Date

March 21 March 21 March 21 March 21 N/A

Time

8:40 8:50 9:50 10:15 PM

 

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