Eta Carinae

Eta Carinae is a massive star within the Milky Way. It is about 100-150 times the mass of the sun, and has only been documented for a few hundred years. With such a young massive star in our own galaxy, Astronomers have been able to find out a lot of information about the life/behaviors of massive stars. This one in particular, has a secondary star that orbits in a 5.5 year cycle, creating an interesting up-down effect of X-rays. When the stars are in the closest part of their orbit, their solar winds cross paths and produce an interesting pattern in their X-rays that appears every 5.5 years.Eta Carinae has also been known because of its giant Humunculus nebula, a cloud of dust and gas that erupted from Eta Carinae's 'great eruption' - an event from the 1840s when it shot to a magnitude -1 in a matter of months. The nebula continues to move outward, heating up to millions of degrees and reflecting the light from this first major explosion.

The white center of Eta Carinae is deemed the 'heart' of the star, where the maximum brightness is almost luminous enough to overturn its own gravity, otherwise known as the 'Eddington Limit.' The light blue areas directly encircling the 'heart' are the areas of radiation shining through the Homunculus nebula. The next layer, of yellow-orange is some of the matter from the 'great eruption,' a total of about ten solar masses. The dark red that serves as the outer ring is the lasting matter from the 1840 explosion, slowly moving into space.

Kalei Sabaratnam
& Devon Ingraham-Adie

The Helix Nebula

What will our sun look like after it dies? Above is the picturesque Helix Nebula, sometimes referred to as ‘the Eye of God.’ A planetary nebula, such as the Helix, is the remnants of a dead star. At the center of this nebula lies a white dwarf, which is a small, hot, dense star, that’s so powerful, it’s the cause of the illumination of the surrounding gas. The green area around the center contains cometary knots—globs of gas that look like comets with their tails pointing toward the center of the nebula. The rest of the nebula is made up of gas and dust left over from the star’s death.

In this false-color composite, the nebula's SII gas is shown in pink and the HaNII gas is blue. These colors combine to make the purple. Towards the interior, as mentioned, the knot-like filaments are shown in green. This is primarily Hb gas.

Omega Centauri

Omega Centauri is the largest and brightest globular cluster in the Milky Way galaxy. At 100 million light years in diameter, it is certainly a colossal being. However, Globular clusters are in fact quite small in the scheme of the universe. What makes Omega Cen, as it's commonly known, so interesting is its varied composition and the history behind it. There are two different populations of Globular clusters, denoted metal rich and metal poor, but Omega Cen actually has stars of both within its cluster; this begins to articulate its wide and varied history as a denizen of galactic space.

Globular clusters are satellite groups of stars that, although primarily found in a galaxy's center, can also be found in a wide and distant halo around a galaxy; sometimes at distances where no other debris or star systems lie in orbit of that galaxy. Because of their relatively small size, but inherent stability as a single unit, globular clusters are commonly traded between galaxies throughout galactic history; our own galaxy is in the process of stealing two globular clusters from nearby dwarf galaxies. Globular clusters are fascinating to astronomers because, even as galaxies collide and are consumed, these clusters remain relatively unaffected, only keeping bits of their pasts within themselves. Presently the most promising source for an unabridged compendium of the universe are these globular clusters.

The Seven Steps of Podcasting

We're going to start talking about actually producing a podcast next week, so it's useful at this point to introduce you to the basics. Jeffrey Daniel Frey works for a university and talks a lot about how to use podcasts in an academic environment. His "Seven Steps of Podcasting" is a nice place to start when we're thinking about the technical side of things.

Research for your Papers, Part II

Some of you have asked about the references that you should/shouldn't use for your papers. Here are my thoughts on that.

If you're a Junior or Senior and a Major or a Minor, you should use the peer-reviewed literature. This means journals like the Astronomical Journal (AJ), the Astrophysical Journal (ApJ), Astronomy & Astrophysics (A&A), Monthly Notices of the Royal Astronomical Society (MNRAS), Publications of the Astronomical Society of the Pacific (PASP), Nature, Science, etc.

If you're not part of that group, you can use those references, but you can (and should) also use references like Sky & Telescope, Astronomy, Scientific American, etc. Some web sites are also good references, but you need to be a savvy consumer of web content; if you have any questions about whether a reference is appropriate, just ask me.

If you don't have much experience reading journal articles (or much experience in Astronomy), you'll probably find that journal articles are a challenge to read. In particular, journals like AJ, ApJ, A&A, MNRAS, and PASP are written for professional astronomers, so there's a certain amount of jargon that's used. Here's a strategy that's useful to use when you're reading these astronomical journals: try starting with the Abstract (which will give you a one-paragraph summary of the paper), then reading the Introduction, then the Discussion & Conclusion. If you want to go deeper, you can read the "Observation" or "Analysis" section, but most of the information that will be most useful to you is in the other sections.

Nature and Science tend to be a bit less "jargon-y", since they're written for the general scientific community, so if you can find an article in one of those journals, so much the better.

Research for your Papers

For the research papers you are writing, you need to go track down resources to help you write your paper. Most major astronomical journals are indexed by the "Astrophysics Data System" (ADS, for short), administered by the Harvard-Smithsonian Astronomical Observatory and NASA. See their search form here:

ADS at Harvard

Note that these link directly to journals, so they are subject to the subscription that each school's library has. If you would like a copy of a paper and your school doesn't have a subscription, let me know and I can get it for you. In particular, if you'd like PDFs of the pages from Scientific American or Sky & Telescope, I have access to the full pages (i.e. including pictures and figures).

Also, before journal articles are published, many authors put them up on the Astrophysics Preprint Server. This is strictly voluntary, so many papers may not be up there. But, as opposed to the Journals, it is completely free to access from anywhere in the world:

Astrophysics Preprint Server ("astro-ph")

Professionally Produced Podcasts

The field of astronomy is changing incredibly quickly. Just over 10 years ago, our view of the universe fundamentally changed with the discovery of Dark Energy. As fast as the science is changing, however, the ways of communicating that science are changing even faster. Just a few years ago, podcasts about astronomical topics were virtually nonexistent (OK: podcasts were virtually nonexistent, but still. . . ). Now, there are hundreds of science podcasts, and (at least) dozens of astronomy podcasts. Here are a few:

• Astronomy Cast is a professionally-produced podcast that typically interviews astronomers about "big ideas." These are a little longer than a typical "podcast," but they do a nice job of showing how an informal approach can work well.
  
• The 365 Days of Astronomy Podcast is produced as part of the International Year of Astronomy (2009) where anyone who wants to can contribute a podcast. Some of these are better than others.
• Slacker Astronomy has a definite informal vibe to it (as suggested by the name); they interview some interesting people and discuss many recent results in Astronomy.
• Some of you may be familiar with Stardate, which are short bits played on a number of public radio stations. Not all of the pieces are similar to what we will be producing in our class, but when they have one about science and physics, they do a good job.
  
• Although it's not exclusively astronomy, the UK-based Naked Scientists also produce a podcast about recent developments in science research and about science in general. One thing that you'll notice about this podcast is that it has much more of a "professional" feel, likely because they also produce this show for radio stations in the UK.
• Sciencepodcasters.org is a collection of several interesting science podcasts from all over. This is mostly just a collection of podcasts produced elsewhere and isn't specifically astronomy-focused, but it's a good place to look to find some good podcasting examples.

Finally, it's worth pointing out that some of the best work in audio presentation is done for the radio. It's usually more long-format material than a typical 5-10 minute podcast, but it's a great place to get inspiration. Radiolab, out of WNYC in New York, is a really excellent science show. It's not specifically about Astronomy, but they really set a gold standard for what can be done with a smart yet informal presenation of complex science topics.

Please mention any science/astronomy podcasts you like in the comments.

The Timescale of the Development of Life

Salman pointed me to a nice example of the expression of scales over at the blog of Seed Magazine. The style is a mash-up between an updated version of Sagan's Cosmic Calendar and the "Kinetic Typography" style that's recently become popular. Much as we talked about in our scales assignment and in the cosmic calendar, it really shows how much "nothing" there is between the start of things and everything that we as humans are aware of.

Powers of 10

As part of your reading/viewing work for next week, I'd like you to look at the "Powers of 10" video. This is a classic example of expressing large numbers in a way that is understandable to the general public. As with Sagan's cosmic calendar, the production values are a little dated, but it's still a great example of expressing large numbers in an interesting way.