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Messier 63 (NGC 5055)
Isaac Embertson

Messier 63

Located a little more than 25 million light-years away from our solar system, M63 (also known as the Sunflower Galaxy) is a bright galaxy with a recognizably spiral shape at a inclined angle. The Sunflower Galaxy was first discovered on June 14, 1779, by Pierre Méchain and is currently classified as a SA(rs)bc spiral galaxy according to the NASA/IPAC Extragalactic Database. Possessing many young blue stars and emission nebulae, M63 is energetic and has several spiral arms emphasized by large amounts of dust. M63 is a significant member of the Canes Venatici constellation, sharing the constellation with the famous "Whirlpool Galaxy", M51.

As is apparent from the image that the visible part of the spectrum corresponding to the color yellow is emitted from the center of the galaxy, suggesting a dense core of older stars with a super-massive black hole in the center. There are numerous blue stars in the outer edges of the spiral arms, showing that new star formation is occurring along the spiral arms. The largest amount of light seems to be coming from the dense core of older stars and these younger stars, but there also seems to be some emission from nebulae in the spiral arms. The patchiness of the spiral arms suggests that the galaxy is a flocculent galaxy and infrared observations show a two-armed spiral structure present in the galaxy. In addition, a faint arc-loop was detected in 1979, which since then has been attributed to a merger with a small dwarf satellite galaxy.

In addition to multiple exposures taken of the galaxy, the size of the object was calculated. Given the distance to the galaxy, it is interesting to find out just how large the Sunflower galaxy is despite its small apparent size. For this calculation, the longest axis was measured on the clear filter image (shown below) and was found to be about 337 pixels long. The shortest axis was also measured and found to be about 185 pixels long (shown below). The data given was binned 2x2, so a scale of 1.32 arc-seconds/pixel was used. The new calculation generated a result of about 445 arc-seconds for the long axis and 244 arc-seconds for the short axis. Given the distance to the Sunflower Galaxy is approximately 25.3 million light-years and the small angle formula ( arc-seconds = physical size divided by the distance), the physical size of the long axis of the galaxy is about 54,000 ly across and the short axis is about 30,000 ly across. According the NASA/IPAC Extragalactic Database, the estimated long axis distance is approximately 26.14 kpc (~85,000 ly) and the short axis distance is approximately 15.16 kpc (~49,000 ly). The inaccuracy of the calculated measurement may be due in large part to inaccuracies and apparent borders of the images used. It can be difficult to determine an exact edge of a stellar object and even more so if the object is very distant.

The angle of inclination was also calculated, as it is apparent that the galaxy is positioned at an angle relative to us. Both axis measurements were used from the size calculations and are shown below.

Long Axis Measurment

Long Axis Measurement

Short Axis Length

Short Axis Measurement

Using the formula for angular inclination (cos (i) = a/b), the angle of inclination was calculated to be 56.7 degrees. This appears to correspond well with the images, as a galaxy with its rim facing our solar system would be at a 90 degree angle and this galaxy is angled a little more than halfway from a flat-on appearance.


Astronomy Picture of the Day. M63: The Sunflower Galaxy from Hubble <>

Constellation Guide. Constellations: A Guide to the Night Sky. Sunflower Galaxy - Messier 63


NASA/IPAC Extragalactic Database. NGC 5055 <>

Right Ascension (J2000) 13:15:49
Declination (J2000) +42:01:45
Filters used B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter B and V (300s); R (180s); C (60s x 5)
Image dimension 1092x736 pixels; 23.8x16.1 arcminutes
Date/time observed March 15, 2017, 4:31 UT

The image shown at the top is the final image of a process. Using a number of bias frame exposures, a combined average bias frame was created. The bias frames were used to remove the read noise that exists in every exposure taken by the telescope. A final flat frame was generated to remove uneven field illumination from existing frames. A dark field frame was created to remove the thermal noise from the exposure frames. The combination of all were used to modify the filtered exposures corresponding to the Blue, Clear, Red and Green filtered exposures. After the final image was compiled from the exposures, the color was adjusted using 1, 1, and 6.5 for the R, G, B values, respectively. A final default Kernel filter was used to refine the details of the image.



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