Hubble’s famous images of galaxies typically show elegant spirals or soft-edged ellipses. But these neat forms are only representative of large galaxies. Smaller galaxies like the dwarf irregular galaxy Holmberg II come in many shapes and types that are harder to classify. This galaxy’s indistinct shape is punctuated by huge glowing bubbles of gas, captured in this image from the NASA/ESA Hubble Space Telescope.
ESO astronomers have used the Wide Field Imager on the MPG/ESO 2.2-metre telescope to capture an image of NGC 6744. This impressive spiral galaxy lies about 30 million light-years away in the southern constellation of Pavo (The Peacock). But this view could almost be a picture postcard of our own Milky Way, taken and sent by an extragalactic friend, as this galaxy closely resembles our own.
In today’s Nature, astronomers discuss the highest resolution imagery taken by the Chandra X-ray telescope of our own Milky Way galaxy. You’ll need a subscription, but there is a interpretive summary of the peer-reviewed paper available online now here (Nature has a great x-ray/visible composite image of M82 on the page), and if you want to see the astronomers’ data itself, you’ll find that online here. The Chandra mission team also has an announcement (available to all) about this published paper, here.
In a paper appearing in today’s Nature, astronomers report on evidence which apparently contradicts the current models of the formation of the most massive galaxies. Most astronomers today feel that galaxies initially formed from density anomalies within the emerging universe as indicated by the most recent cosmic microwave background radiation measurements of the WMAP satellite. As stated by these authors “findings suggest a new picture in which brightest cluster galaxies experience an early period of rapid growth rather than prolonged hierarchical assembly.” Read more about the formation of the most massive galaxies in the universe online now here.
In a press release yesterday, coinciding with their announcement at the American Astronomical Society’s 213th National Meeting in Long Beach California this week, scientists from the Harvard Smithsonian Center for Astrophysics announced that the Milky Way galaxy is larger and rotating faster than originally thought. Observations made with the radio telescope system known as the Very Long Baseline Array (VLBA), forced astronomers to resize the Milky Way and increase its known rotation rate. To learn more about this, see the press release at http://www.cfa.harvard.edu/press/2009/pr200903.html Now don’t jump the gun and conclude that everything is further away than we thought. Just today, astronomers at the National Radio Astronomy Observatory in Socorro, New Mexico, utilizing the same VLBA, recalculated the distance to a celestial object called IRAS 00420+5530 and determined that it is actually about half the distance than originally thought. Read these astronomers results online at http://xxx.lanl.gov/PS_cache/arxiv/pdf/0901/0901.0517v1.pdf