NASA’s Hubble Space Telescope brings the vastness of space into perspective in this mosaic image of the Triangulum galaxy (M33), our neighbor in a collection of dozens of galaxies called the Local Group.
The unprecedentedly detailed portrait of Triangulum is composed of 54 Hubble fields of view stitched together, revealing nearly 25 million individually resolved stars. The borders of individual Hubble images trace the jagged edge of the mosaic, which spans 19,400 light-years across. Striking areas of star birth glow bright blue throughout the galaxy, particularly in beautiful nebulas of hot, ionized hydrogen gas like star-forming region NGC 604 in the upper left.

Triangulum is oriented with its face toward us, ideal for studying the distribution of stars and gas in its well-defined spiral structure. While astronomers are still delving into the immense trove of data collected by Hubble, a few characteristics stand out immediately, inviting key comparisons and contrasts with our own Milky Way galaxy and the third large spiral in the Local Group, the Andromeda galaxy.

“My first impression on seeing the Hubble images was, wow, that really is a lot of star formation,” said astronomer Julianne Dalcanton of the University of Washington in Seattle, who led the project. “The star formation rate intensity is 10 times higher than the area surveyed in the Andromeda galaxy in 2015.”

Astronomers think that Triangulum has been an introvert, avoiding disruptive interactions with other galaxies, instead spending the eons tending its well-ordered spiral and turning out new generations of stars. Further research may determine if Triangulum is actually a newer member of the Local Group of galaxies, and perhaps its quiet days will soon be over.

This mosaic was created from images taken by Hubble’s Advanced Camera for Surveys between February 2017 and February 2018. The panoramic image will be presented at this week’s 233rd meeting of the American Astronomical Society in Seattle, Washington [https://aas.org/meetings/aas233].

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Text & Graphics: http://hubblesite.org/news_release/news/2019-01