                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2019 October 3

                         The Hydrogen Clouds of M33
     Image Data: Subaru Telescope (NAOJ), Hubble Space Telescope - Image
                         Processing: Robert Gendler
    Additional Data: BYU, Robert Gendler, Johannes Schedler, Adam Block -
              Copyright: Robert Gendler, Subaru Telescope, NAOJ

   Explanation: Gorgeous spiral galaxy M33 seems to have more than its
   fair share of glowing hydrogen gas. A prominent member of the local
   group of galaxies, M33 is also known as the Triangulum Galaxy and lies
   a mere 3 million light-years away. The galaxy's inner 30,000
   light-years or so are shown in this magnificent 25 panel telescopic
   mosaic. Based on image data from space and ground-based telescopes, the
   portrait of M33 shows off the galaxy's reddish ionized hydrogen clouds
   or HII regions. Sprawling along loose spiral arms that wind toward the
   core, M33's giant HII regions are some of the largest known stellar
   nurseries, sites of the formation of short-lived but very massive
   stars. Intense ultraviolet radiation from the luminous, massive stars
   ionizes the surrounding hydrogen gas and ultimately produces the
   characteristic red glow. To enhance this image, broadband data was used
   to produce a color view of the galaxy and combined with narrowband data
   recorded through a hydrogen-alpha filter. That filter transmits the
   light of the strongest visible hydrogen emission line.

                     Tomorrow's picture: pixels in space
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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