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Messier 90 (NGC 4569)
Stephen Sykora

Messier 90

Messier 90 (M90), or NGC 4569, is a spiral galaxy in the Virgo cluster discovered by Charles Messier in 1781 . The galaxy is about 12.2 Megaparsecs, roughly 40 million Light-years away, and is currently moving towards us within the Virgo cluster at 383 meters per second, the second fastest blueshifted galaxy in the Messier catalog.

Messier 90 is inclined at an angle of 62 degrees to Earth, found by taking the arccosine of the major axis of 9.5 arc minutes divided by the minor axis of 4.4 arc minutes. Because the galaxy is seen at an angle, it appears smaller than the galaxy would be if the galaxy was observed face-on, even so, M90 is one of the larger galaxies in the Virgo cluster, with a major axis of 109,960 Ly and a minor axis of 50,929 Ly, found by multiplying the major and minor axis in radians by the distance to M90 in Light-years.

With M90 being a spiral galaxy, an astronomer would expect to find some regions of active star formation, normally indicated by small pink blobs, or young blue stars in the spiral arms. But M90 has been fossilized, most of its gasses have been stripped away, leaving the galaxy almost entirely white and yellow. While the small irregular galaxy orbiting it, IC 3583, has a blue shade that indicate recent star formation.

2.6mm band

The picture above is of M90, targeting light in the 2.6 mm wavelength. Carbon monoxide emits light at this wavelength and CO is often found with Hydrogen gas. The picture is 1x1 arc seconds across, so this is just an image of the core. This shows that the only areas of the galaxy that has some star formation is inside the core, where all optical signs are hidden.


This is a near-infrared image of M90. Light in the near-infrared wavelength is not scattered by dust as easily as visible light. In other words, objects can be seen in the near-infrared spectrum when they would be blocked by the clouds of dust that are in nebulae and the arms of a galaxy. This image shows that spiral shape of the arms in M90 comes more from the dust than from stars.


Guy McArthur, Hartmut Frommert, Christine Kronberg. "Messier 90." Messier Object 90. N.p., n.d. Web. 08 May 2017. "Spotlight on IC 3583." N.p., n.d. Web. 08 May 2017.
Interstellar Medium and the Milky Way. N.p., n.d. Web. 08 May 2017.
Interstellar Medium and the Milky Way. N.p., n.d. Web. 08 May 2017.
"NASA/IPAC Extragalactic Database." By Object Name | NASA/IPAC Extragalactic Database. N.p., n.d. Web. 08 May 2017.
Your NED Search Results. N.p., n.d. Web. 08 May 2017.


Right Ascension (J2000) 12:36:50
Declination (J2000) +13:09:46
Filters used B (Blue) V(Green/Visible) R(Red) C(Clear)
Exposure time per filter B(300s x 15) V(180s x 10) R (120s x 6) C (60s x 248)
Image dimension 972x722 pixels; 21.4x15.9 arc minutes
Date/time observed March 17, 2017 March 18, 2017 March 18, 2017 April 5, 2017
Processing Details The images where calibrated with bias, dark, and flat fields, then combined into master images for each filter. In each master image, dead pixels where blended in by hand, then the masters where combined into a single LRGB image, with color adjustments.



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