NGC 4214

Observatory / Course Archives / ASTR 212 Spring 2019 / Smith

Far off in the universe (roughly 10 MILLION light-years!) lies a tiny little dwarf galaxy categorized as NGC 4214. Specifically, it is a dwarf barred irregular galaxy. The 'dwarf' part of its description describes this galaxy's stellar mass as ranging from 100 million to several billion stars (NASA/IPAC). Some dwarf galaxies (such as this one) are thought to originally be barred spiral galaxies that have been distorted by the tidal interactions between galaxies. This particular galaxy can be found within the Canes Venatici constellation. Interestingly, it is quite the hotbed for new star formation and is classified as a starburst galaxy (Ubeda).

We can see that NGC 4214 is quite a bright galaxy for its size and the color of light that it gives of indicates a young stellar population. This is indicative of a large amount of star formation, which coincides with Ubeda's classification as a starburst galaxy. The image also shows the irregularity of this galaxy. It is difficult to discern any specific form within the galaxy. One can see, however, that this galaxy is 'barred' as it clearly does not form a uniform circle (though this could simply be because we are not looking at the galaxy head-on).

The second image taken with the Hubble Space Telescope does a better job of displaying the ongoing star formation within this galaxy. The large blue area near the center shows that the stars within this galaxy are young and hot. The vast amount of gas within the galaxy also helps to feed star formation here. The clouds of gas within this galaxy are glowing due to the hot UV light being emitted by the young stars (R. O'Connell). The hot UV light ionizes the hydrogen gas within the clouds, causing the clouds to grow a pinkish-red hue.

NGC 4214 can be seen to be very small. From the image created for this course, it was measured to have a major axis length of 23,000 light-years and a minor axis length of 17,000 light-years (measured with an estimated distance of 8.10 Mpc according to NASA). For comparison, the Milky Way is roughly 100,000 light-years across (Frommert and Kronberg). Quite the difference in size!

In an attempt to verify the irregularity of NGC 4214, a de Vaucouleurs profile was developed for this galaxy. The de Vaucouleurs profile is applicable for elliptical galaxies. It is defined by several variables, one of which is the parameter Re, which represents the radius which contains half the luminosity of the galaxy. The de Vaucouleurs profile and curve fit was created using Logger Pro.

The "C" value on this curve fit corresponds with the variable Re. This graph gives an Re of 4910+/- 2504px, which corresponds to 830 +/- 423 kilolight-years. Obviously, this number is incorrect as it is an order of magnitude larger than the actual size of the galaxy. Additionally, the high uncertainty of this value shows that the system does not fit well into a de Vaucouleurs profile. This was expected given its classification as a dwarf barred irregular galaxy.

References:

 "NASA/IPAC Extragalactic Database" http://ned.ipac.caltech.edu/byname?objname=NGC%204214&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1

Ubeda, L.; Maíz-Apellániz, J.; MacKenty, J. W. (2004). H.J.G.L.M. Lamers; L.J. Smith; A. Nota (eds.). "Massive Young Star Clusters in NGC 4214". The Formation and Evolution of Massive Young Star Clusters, ASP Conference Series.

NASA, ESA, Hubble Heritage Ack. R. O'Connell, "Dwarf Irregular Galaxy NGC 4214 Imaged by Hubble WFC3"; http://hubblesite.org/image/2846

Frommert, Hartmut and Kronberg, Christine, http://www.messier.seds.org/more/mw.html

 

Right Ascension (J2000)	12:15:38.8
Declination (J2000)	36:19:39.0
Filters used	B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter	B (300s x 15); C (60s x 28); R (60s x 7); V(120s x 5)
Image dimension	377x321 pixels; 8.17x6.96 arcminutes
Date/time observed	03/05/2019, 5:53 A.M.

The raw images were calibrated using combined bias files and flat files only. The calibrated images were then combined by filter, and color-combined using MaxIm DL Pro 5. The infrared image is displayed as "Red," the red image as "Green," and the green image as "Blue," and the balance values were set to 1.5, 1, and 1.9, respectively. The luminance weight was set to 70% and the saturation set to 150%. Finally, the image was converted to JPEG format and cropped to a size of 377x321 pixels.