The Hubble Space Telescope has captured the best-ever image of the galaxy next door, the Triangulum galaxy (M33). He subsequently documented when in their history these Local Group dwarf galaxies stopped making stars, or "quenched", and how this was affected by the proximity of the larger galaxies, including the Milky Way. See the full image here. The galaxy is usually visible as a faint, blurry object under dark-sky conditions. It is massive in size, as the above image is estimated to contain between 10 and 15 million stars, "an order of magnitude less stars than the Milky Way and two orders of magnitude less than Andromeda", according to Hubble's website.
Triangulum, also known as Messier 33 or NGC 598, is part of the Local Group - a collection of more than 50 galaxies, including the Milky Way, that are bound together by gravity.
It measures only about 60,000 light-years across, compared to the 200,000 light-years of the Andromeda Galaxy; the Milky Way lies between these extremes at about 100,000 light-years in diameter.
The runt of the litter also lacks the conventional bright bulge at its heart and does not have a bar connecting its spiral arms to the center. That huge amount of gas and dust allows for rapid star formation, at a rate of approximately one solar mass every two years.
The Andromeda Galaxy was mapped by Hubble in 2015, creating the sharpest and largest image of this galaxy and the largest Hubble image ever. Hubble has just released its most detailed view yet of that galaxy, which is known as Triangulum (can you see why?). Today, September 9, 2009, NASA released the first images taken with the Hubble Space Telescope since its fix in the spring.
He received the 2019 Newton Lacy Pierce Prize "for his transformational work on the star-formation histories of dwarf galaxies in the Local Group, our galactic neighborhood". "By counting up all the stars of different ages in a galaxy, it's possible to reconstruct a galaxy's star-formation history - that is, how many stars formed at a given time - over the entire history of the universe".
Astronomers think that Triangulum has avoided disruptive interactions with other galaxies, instead spending the eons tending its well-ordered spiral and turning out new generations of stars.