New moon weekend is back - and we're free to go deep sky observing from nearly dusk to dawn! This weekend, let's visit some interesting views of galaxies that contain star birth regions, also known as HII regions. (Pronounced H-Two). We have these in our own Milky Way, most notable among them is the winter favorite: the Great Orion Nebula - M42. When viewing these HII's in your telescope, imagine them as they might be seen from only a few thousand light years, rather than their actual distance tens of millions of light years away. Find the first two galaxies in the early evening, then the last later at night, the weekend of August 2 and 3, 2013.
M101 is the classic example of a big galaxy full of star birth regions. It is 21 million light years distant, and appears faint visually due to its large size. Many of the HII regions in it were thought to be distinct objects apart from M101, and assigned their own number in the New General Catalog. In a dark sky you can see the HII's in M101 - NGC 5462, NGC 5461 and NGC 5447. These will look like small grayish brightened lumps in the arms of the galaxy. I find it convenient to use the Big Dipper to star hop to M101. Starting at the handle star of the bow, I draw an arc from star 1 to 2, to 3, then arc slightly to M101 at 4.
M82 is paired with the spiral galaxy M81. They sit 12 million light years distant. Sometimes called the Cigar Galaxy for its elongated shape, M82 appears bisected by a dark intrusion across the near center of its minor axis. On both sides of the dark intrusion are glowing HII regions, where active star birth is taking place. I hop to these galaxies by crossing the bowl of the Big Dipper (1 to 2), extending a bit more than that distance to a naked-eye star (3), then move just a bit north. A wide field eyepiece may provide a nice view of both galaxies in a single field!
M33 is called the Triangulum Galaxy - a nearby member of our own Local Group of galaxies (of which our Milky Way is the second largest member), and only 3 million light years from us. This time of year you can see it low in the northwest soon after dusk. With good conditions in a dark sky, you may glimpse M33 naked-eye as a faint large glow. Hop from Beta Andromeda (off the Great Square of Pegasus) to the point star in the constellation Triangulum. M33 is about 2/3rds the distance, and a touch west. Four NGC HII regions are in M33, most notable is NGC 604, which is equivalent to our own Orion Nebula.
Mark Wagner is a life-long astronomy enthusiast and deep sky observer. He has spent the past twenty years popularizing amateur astronomy in the San Francisco bay area through his writing and community building. A past president of the San Jose Astronomical Association, he founded what is now the annual Golden State Star Party in California. Please post if you have comments, questions, sketches or images you've taken of the targets mentioned above.