Pretty Pictures
sb admin | June 29, 2007NGC 7331 is a spiral galaxy, probably not too dissimilar from our own (except that it lacks a bar), which is relatively nearby. (At a mere 49 million light-years, it's not in our own back yard, but it's just down the block.)
Image: Paul Mortfield and Dietmar Kupke/Flynn Haase/NOAO/AURA/NSF
Several years ago, the first time I thought Astronomy 253 ("Galactic Astrophysics"), I had an entire problem set entitled the "NGC 7331 problem set." In fact, this was a general problem set about the properties and dynamics of spiral galaxies, but I chose NGC 7331 as the example that was referenced in…
sb admin | June 22, 2007NGC 5135 is a barred spiral, similar in some ways to NGC 1365. Both galaxies are members of the IRAS "Bright Galaxy Sample," meaning that they are very luminous in the infrared as a result of vigorous star-forming activity. Both have very strong bars. Both harbor an active galactic nucleus at their core. (All large galaxies are believed to have a supermassive black hole at their core, but only a small fraction of those black holes are actually being fed; it is the feeding of the black hole that triggers the AGN.) And, both have been observed by Katie Chynoweth and I as part of our (sadly…
sb admin | June 8, 2007The image below is an image taken in 1994 with the Hubble Space telescope of galaxy NGC 4526:
Image: NASA, ESA, The Hubble Key Project Team, and The High-Z Supernova Search Team
The bright spot in the lower left is the supernova known as SN1994D. This is a Type~Ia supernova, type type of supernova that has been used by several times (initially two, the one that I was in, and the one that this image is credited to) to measure the expansion history of the Universe, and to discovery that the expansion is accelerating (requiring that there be that which we now call "Dark Energy" filling the…
sb admin | May 25, 2007VV114 is a very interesting galaxy. It's a major merger of at least two big galaxies. If I might go out on a limb, it may even be an advanced merger (on the left) currently strongly interacting with another galaxy (on the right).
The left galaxy is extremely dusty. Sunsets are red because particles in the atmosphere preferentially scatter away the bluer light. Redder light penetrates the dust better. Just before the Sun sets, we're looking at it through as much atmosphere as we ever see it, so it has to go through the most number of particles in the atmosphere. similarly, very dusty…
sb admin | April 27, 2007Are you ready for this? This week's Friday Galaxy is Mk509:
DSS2 image from Skyview
Admittedly, the image of this galaxy does not rank very high on the "wow, what a cool and pretty looking galaxy" scale. However, this is an interesting galaxy because of what's going on at the nucleus. Like all large galaxies, there is a supermassive black hole at the core of this galaxy. The black hole in this galaxy is being fed, giving rise to what we call an Active Galactic Nucleus (AGN). If you drop gas down into an accretion disk near a supermassive black hole, a tremendous amount of gravitational…
sb admin | April 16, 2007Here are images of two more galaxies. These weren't taken during the current run, but in a previous run. Last November, I was also down at CTIO with some students. I was doing blazar work on the 1.0m telescope (not to be confused with the 0.9m telescope I'm using right now), and shot off some images of the galaxies that Katie was observing spectroscopically. The two galaxies below are those galaxies.
The first is NGC 1614:
This galaxy has what we in the biz call a "disturbed morphology." It's not just a clean spiral galaxy, and it's certainly not an elliptical galaxy. Sticking off…
sb admin | April 14, 2007I apologize for my silence of the last few weeks; real life gets busy at times. This time, I was in a crunch finishing up things before running off to an observing run at the CTIO Observatory in Chile. That's where I am right now. I'm at the 0.9 meter telescope doing imaging of "blazars," a class of active galactic nuclei that sometimes vary on timescale of minutes (which is surprising if you know how big galaxies are). My graduate student Katie Chynoweth is observing on the 1.5 meter telescope, doing spectroscopy of infrared-luminous galaxies.
Below is an image — really, a composite of…
sb admin | March 23, 2007M82 is a galaxy that's relatively near to the Milky Way. It's not in our own local group, but it's in a nearby group of galaxies (the "M81 group"), and is only about 12 million light-years away (which is close for a galaxy). It's notable because it's a "starburst" galaxy— it's undergoing a burst of rapid star-formation, producing large numbers of stars in big clusters in a relatively short period of time. A lot of this activity is near the nucleus of the galaxy.
M82 is a favorite target for infrared astronomers. My cohort in graduate school, James Larkin, wrote his first grad school paper…
sb admin | March 16, 2007This is an image of NGC 6744, taken with the South African Large Telescope.
NGC 6744 is a classic spiral galaxy, and appears similar to how the Milky Way would look if we were able to get outside of the Milky Way and look back at it. Notice that there is a bar at the center of the galaxy (oriented vertically in this picture). That is a feature that you see in a lot of spiral galaxies, and which indeed is present in our own spiral galaxy.
This image isn't exactly how the Milky Way would appear to our eyes. First of all, the surface brightness of the galaxy is low enough that our eyes…
sb admin | March 10, 2007It's called "The Milky Way" because if you don't know what you're looking at, it looks like a hazy, nebulous path across the sky.
But try this : go down to Chile, or somewhere else in the Southern Hemisphere. Go outside at a nice, dark site, and stay out there so your eyes adapt. If the galaxy is passing overhead, you will see something like this:
This is a picture taken by an all-sky cloud monitor camera at the Cerro-Tololo Inter-American Observatory. Around the edge of the picture is the horizon; you can see the silhouettes of the telescope domes. And, directly overhead, is the big…
sb admin | March 2, 2007This is face-on spiral galaxy IC 342, taken with the Mosaic-1 Camera on the 4m Kitt Peak telescope by Travis Rector and Heidi Schweiker. (Image credit: T.A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN, and NOAO/AURA/NSF).
It was released by NOAO a week ago at a symposium in Washington, DC on light pollution. Here is the NOAO press release.
sb admin | February 23, 2007In the tradition of "Friday Cat Blogging" (in which I will doubtlessly indulge at some point, what with being a nutty cat person), I intend to establish my own tradition of putting up some pretty picture or another of a galaxy each Friday. Today is barred spiral galaxy NGC 1365.
The spiral arms in this galaxy are apparent, as is the bar; this is one of the classic examples of a barred spiral galaxy. It was also the subject of a poster presented a month and a half ago at the AAS meeting in Seattle by my grad student, Katie Chynoweth. These images were taken by me with the 1.0m SMARTS…