Image credit: NASA, ESA, and Judy Schmidt

Key Takeaways

  1. Messier 100 (M100), also known as NGC 4321, is a captivating spiral galaxy located in the constellation Coma Berenices.
  2. As part of the Virgo Cluster of Galaxies, M100 can be observed by “galaxy hopping” from the M84/84 pairing in the core of the cluster.
  3. M100 boasts two distinct arms of young, massive stars, which shine brightly in blue.
  4. The galaxy’s unique features, such as its asymmetric H I distribution and the presence of a nuclear bar, provide valuable insights into its dynamics and evolution.
  5. Astronomers have made fascinating discoveries about M100, including its interaction with a companion galaxy and the observation of a supernova, SN 1979C, that continues to shine brightly in X-rays.

Messier 100, also known as M100 or NGC 4321, is a breathtaking spiral galaxy that resides in the constellation of Coma Berenices. As part of the illustrious Virgo Cluster of Galaxies, locating M100 requires employing the technique of “galaxy hopping.” One must first identify the M84/84 pairing in the heavily populated core of the Virgo Cluster, and from there, sweep the telescope northward until the grand spectacle of M100 is revealed. This face-on presentation of M100 offers a round patch of nebulousity, making it a delightful sight for both amateur and experienced stargazers, especially under dark, clear skies or with binoculars.

The spiral structure of M100 closely resembles that of our own Milky Way. Its two distinct arms, adorned with young, hot, and massive blue stars, are the result of recent interactions with neighboring galaxies. Interestingly, M100 displays an asymmetric distribution of hydrogen gas (H I), indicating possible deviations from circular motions in the outer disk. This could be attributed to a close passage of the companion galaxy NGC 4322, which also accounts for the observed asymmetry in the total H I distribution. M100’s dynamics are further intriguing due to the presence of a nuclear bar, deduced from the velocity field, revealing gas streaming around the bar in elongated orbits.

Moreover, M100 has made history by harboring the remains of the supernova SN 1979C. Unlike typical supernovae, which fade rapidly, SN 1979C continues to emit bright X-rays even after more than two decades. This enigmatic behavior allows scientists to study the star’s history, including its stellar wind dating back 16,000 years before the explosion, providing unique insights into the phenomenon. The European Space Agency’s XMM-Newton observatory played a pivotal role in observing and capturing this rare occurrence.

First discovered by Pierre Mechain in 1781 and later confirmed by Charles Messier, M100 has fascinated astronomers throughout history. The contributions of distinguished astronomers like Admiral Smyth and Sir William Herschel have shed light on its extraordinary features and its place within the grand stratum of nebulae that stretches across the night sky. Today, Messier 100 continues to be a captivating subject of study, offering a glimpse into the fascinating dynamics and evolution of spiral galaxies.

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This very detailed image shows the main features expected in a galaxy of this type: huge clouds of hydrogen gas, glowing in red patches when they re-emit the energy absorbed from newly born, massive stars; the uniform brightness of older, yellowish stars near the centre; and black shreds of dust weaving through the arms of the galaxy. Credit: ESO


The spiral galaxy M100. Credit: ESO


Messier 100 spiral galaxy in the Virgo Cluster, imaged using the 24 inch Schulman Foundation telescope on Mt. Lemmon, AZ. The satellite galaxies are NGC 4323 (bottom center) and NGC 4328 (bottom right). Credit: Jschulman555


This image, taken with the high resolution channel of Hubble’s Advanced Camera for Surveys demonstrates the continued evolution of Hubble’s capabilities over two decades in orbit. This image, like all high resolution channel images, has a relatively small field of view: only around 25 by 25 arcseconds. Credit: ESA/Hubble & NASA


Credit: Bart Delsaert


Messier 100, also known as NGC 4321, is one of the largest and brightest spiral galaxies in the sky, located at about 50 million light-years from us. A composite VRI image obtained on March 3, 2002. The individual exposures lasted 180 seconds, image quality 0.7 arcsec FWHM; field 7 x 7 arcmin2 ; North is up and East is left. Credit: ESO


The galaxy Messier 100, or M100, shows its swirling spiral in this infrared image from NASA’s Spitzer Space Telescope. The arcing spiral arms of dust and gas that harbor star-forming regions glow vividly when seen in the infrared. CREDIT: NASA/JPL-Caltech


This picture is a combination of images from the Apogee Aspen CG16M CCD instrument mounted on CofC’s 24 inch telescope , taken with red (R), green (V) and blue (B) filters. Exposures R: 3x300sec, V: 3x300sec, and B: 3x300sec

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