We invite you to join us, and ask you to please announce the Astronomy Cast Live Feed on your blog if you have one. This is going to be a Spring Break AstroFest like no other. While you won’t be seeing any bikini clad astro babes, we may bring you some naked facts and uncover some planetary surfaces along the way.

Enjoy!

Case in point, let’s consider that “Largest Planet.” When I see the word largest, I tend to think high mass and high radius. This new world, discovered by an international team using the Trans-atlantic Exoplanet Survey (TrES) network of telescopes, is in fact lower in mass than Jupiter, but sports a radius 1.67 times larger than Jupiter’s. So, it is large in radius but well below average in mass. In fact, the paper could have just as easily been titled “Lowest density exoplanet found.” So, it’s exciting, but confused. And what’s more, as we get more data on other worlds we may find some of the other planets are actually larger in radius! With today’s technology we can only measure the radius of planets that transit their host star. This is a small part of the total population. With future missions, like Darwin or the Terrestrial Planet Finder, it will be possible to start to image planets directly, and we’ll be able to get better measurements of planetary radius.

So, at the end of the story, it was just another bloated hot Jupiter (admittedly way more bloated than normal). None the less, it made the news (I heard about it on NPR). If it bleeds it leads, and if its a planet its at least printed.

Turning away from the planet of false promises (it would have been so cool if it was the most massive – then I’d be able to compare it to the smallest brown dwarf and have a neat discussion on the boundary lands between planets and stars), I popped open the piece on a Black Hole feeding frenzy. I have to admit, my mental image of a feeding frenzy comes from National Geographic specials on sharks. When I read this headline I imagined gas and dust being messily gobbled with bits of material getting flung about even if most of the matter was getting consumed. As strange as this may sound, my mental image perfectly matches this scenario. It appears some galaxies periodically gravitationally suck in large clouds of gas and dust or small gas rich galaxies. When these systems get sucked in, they fall apart, with much of their mass falling into the galaxy’s central supermassive black hole. While feeding, the supermassive black hole lights up and becomes a quasar. As the material streams in, some of it’s torn off and ejected in a new direction, like the bits of fish flung in a aquatic feeding frenzy.

Astronomers had believed this was how quasars were fueled for a long time, but they’d had problems proving the consumed material came from outside the quasars. What is new in this work, done by Hai Fu and Alan Stockton of the University of Hawaii, was the discovery that the larger galaxy had lots of heavy atoms that had been produced in stars while the consumed gas was basically pure hydrogen and helium. This made it clear the consumed material had to have come from outside the galaxy – proof that the theorists got it right.

This leaves us with one more Monster tale. Using the Spitzer Space Telescope and WYIN telescope, astronomers Rose Finn (Siena College) and Alexey Vikhlinin (Harvard-Smithsonian CfA) discovered 4 giant galaxies – galaxies that have an average mass larger than out Milky Way – in the process of merging. All previously imaged mergers had either involved smaller galaxies or fewer galaxies, or most likely both fewer and smaller galaxies. If you are willing to go with the “A large truck is a monster truck,” then it’s not a stretch to say a large galaxy is a monster galaxy, and these monster galaxies are piling up in the center of this cluster.

So, at the end of the day, we have one misleading use of the word “large,” one good use of feeding frenzy, and one stretched analogy involving monsters. And, the authors sucked me into reading all their stories, one potentially abused word at a time.

• Scientists have (again) found new tidal streams of material around the galaxy from a previously unknown, now shredded galaxy
• Scientists have (again) found a new explanation of how the Sun heats its chromosphere
• Scientists have (again) dated the Crab Nebula explosion to 1054 AD

New results, new press conferences and press releases, and, well, the same old same old. Science moves forward in incremental steps, and sometimes things circle and circle as they slowly move forward.

Part of moving forward is building bridges between communities, forming partnerships, and creating collaborations. As well a blogging this meeting, I’m spending a lot of time talking. I’m going to save discussing how these new results with recycled headlines move science forward until I can spend time talking in detail.

While you wait (if you are waiting – others are blogging remotely and locally too), tune in to The Universe on the History Channel (check you local listings). As the ad in the upper right shows, I’ll be the official blogger for the series.

Flipping over to the arXiv e-print service, a different picture emerges. The couple dozen submitted works for Wednesday, May 9, spanned subjects from string theory to CMB Anisotropies and the outer Solar System (1, 2). Some papers are still in peer review, and others will never be submitted to journals. All the papers are sitting there waiting to be read and learned from, and hopefully someday cited by someone not on the author list.

A quick survey of the pdfs finds information on the following topics (warning: my choice of grouping may not match yours): satellite orbits, observatory sky brightnesses, high redshift galaxies (2), computer models (3), the sun (2), the CMB, black holes (3), gamma ray bursts (3), star formation, dark matter, star clusters, theoretical astronomy (3), masers, compact objects that aren’t black holes (3), rare star types, galaxy formation, dark energy, supernovae, and galaxy evolution. The authors range from students (including someone I was at the University of Texas with), to senior faculty, to one potential crazy. The field of astronomy is alive and well, and it’s exploring many things that almost no one will ever know about.

I don’t know the exact statistics on how many people are likely to read the typical astronomy journal article within the first year after its publication. I expect that stating a good paper has its abstract read by a few hundred people is probably fair. I suspect that same paper might be read in its entirety by maybe a few tens of people. There are two simple reasons these articles get so little coverage: 1) There are dozens of papers published a day and no one has the time to read all of them and accomplish anything else, 2) Many of these papers are so highly technical that someone not actively doing research in the specific sub-field of the paper won’t be able to understand the content without reading many of the papers referenced as well. So… Except when someone does something that just sounds really cool, or when someone does something picked up by the media, most of what is getting discovered gets ignored.

The media (and the press officers who feed us content) tend to latch on to specific types of content. Anything that can have an adjective like largest, smallest, nearest, farthest, youngest, oldest, is fair game. For whatever reason, Guinness hit on a great thing with their book of world records – People are inherently interested in extremes. Stories related to extremes can sell a magazine/newspaper/TV show, so… That is what gets written about. Almost anything related to a planet (in our solar system or another solar system) can also be made media sellable, as can almost any discovery related to the beginning and end of the universe. These stories touch on the questions we ask as 5-years olds and still hope to have answered as adults: Can we explore other worlds, is there life beyond our Earth, where did we come from, and where are we going? To try and sate their curiosity, people will pay for planet-related publications and ignore the cost of cosmology-centric content. So, the press feed gives the public what they will purchase – in this case planets and cosmic prognostications – and the rest of the cosmos gets ignored.

That’s not to say everything on arXiv is worth publicizing. There is a lot of mind-numbing adding of decimal places to results and theoretical work that just may not result in anything. There is also really good science that is just filling in of details. This is hard and worthwhile research, but not necessarily the stuff Joe Public really needs taking up space in his head. Still, in the midst of all that is going on, there are cool things getting missed.

For instance, there were three neat results potentially worth knowing about in today’s news. In order of upload, the first paper that caught my eye looked at the nearby Leo A Dwarf Galaxy. This little system is a member of our local group, and lurks about 800,000 parsecs (2,600,000 light years) away from the Milky Way. It shows evidence of multiple epochs of star formation and still has hydrogen gas waiting to make some future generation of stars. By carefully measuring the velocities of a dozen carefully chosen stars, a team of Smithsonian Astrophysical Observatory observers lead by Warren Brown determined that Leo A also has significant levels of dark matter. Specifically, Leo A appears to be made of at least 80% dark matter. This result comes from carefully adding up the stars’ luminous mass and then theoretically determining how much additional mass is needed to make the observed stars and previously observed gas orbit Leo A with their measured velocities. This isn’t the first system found with this level of dark matter, but that’s what makes this result so neat for me. High levels of dark matter are typically found in dwarf spheroidal (dSph) galaxies – the little guys that dance in the halos of giant galaxies like the Milky Way and Andromeda. dSph galaxies are generally dead, with no current star formation, and in some cases only one identified past generation of star formation. Leo A isn’t a dSph. It’s a dwarf irregular. I know, subtle difference only an astronomer can love and all that… BUT, Brown and his team point out that as Leo A ages and fades, it will look progressively more like a dSph. We are seeing in this little system what a lively dSph may look like, and demonstrating dark matter is always there in the same proportion. A new evolutionary link is built stronger as this paper works to flesh out how galaxies move through the Hubble classification system.

In a separate result, Kalirai et al. used Keck Observatory to discover unusual white dwarf stars in the old open cluster NGC 6791. This star cluster was formed roughly 8 billion years ago and is one of the oldest known star clusters. It also has an unusually high metal content (which means the gas that formed the stars had been enriched with a lot of material from supernovae and mass loss. In this case, the stars have roughly twice the amount of heavy elements the Sun has.). For complex reasons, many of the red giants in this cluster had high mass loss rates. Normally, red giant stars burn hydrogen in shells around their helium cores (these cores were formed while the stars were on the main sequence and were burning hydrogen to helium like the Sun.) Generally, this hydrogen dumps enough helium onto the core and burns hot enough that eventually the helium core ignites and burns helium into carbon. In stars like our Sun, the carbon core will eventually become the seed of a future white dwarf with a mass greater than 0.46 solar masses. In NGC 6791, however, high mass loss rates prevented the helium from ever igniting, and the stars died as helium-core white dwarfs with masses well under 0.46 solar masses. This is neat to me for a couple of reasons. First, this is a cool path for stellar evolution that doesn’t generally crop up in Astronomy 101. I like being able to point out flaws in text books. Second, this means that in really metal rich systems whole classes of stars, like Mira variables, may not form in large numbers because their progenitors just won’t live long enough. This means that as our universe becomes more and more enriched with heavy metals, the Mira variables so often observed by amateur astronomers may become more rare. It’s a bit of a downer, but still cool.

Just to have full disclosure, the final paper that caught my eye is co-authored by one of my friends from graduate school, David Fisher (primary author is Niv Drory). I have to admit I looked at the paper first because of the topic, and then had a “Cool – I know him” moment when I looked at the author list. The science that caught my eye is a potential new way to use galaxies’ colors to get at additional information. Spiral galaxies can be loosely grouped into those that are blue (actively forming stars and coming in all sorts of “shades” (not a scientific term, exactly) of blue, and red systems that are all very similar in color (falling on the red sequence, scientifically speaking)). Measuring galaxy colors is, in the grand scheme of things one can do with a telescope, fairly easy. The trick comes in understanding what these colors mean beyond the bland “Star forming” and “Not star forming (a lot)” labels. Using the Hubble Space Telescope, Drory and Fisher discovered that spiral systems that are red have classic bulges indicating some sort of a violent event in the past that created this elliptical structure in the middle of the disk and cut off some star formation. In blue systems, however, there is what is called a pseudo-bulge – a stirred up part of the disk – that is blue and indicates the system has thus far escaped harms way. Now, this isn’t a universal rule. A red spiral system that has some dust and gas can be made blue through violent collisions that trigger new star formation, but this color changing event also changes the systems morphology. With these results, it is possible to say that when you find a red, undisturbed spiral, you are finding the survivor of a past collision.

In selecting these stories, my own personal biases come out. I am personally drawn to stories of evolution. We live in a dynamic and changing universe, and we are learning more each day about how each type of object will grow and change throughout its lifetime. The universe, like a forest, is a changing thing whose structure is dictated by the life cycles of its parts. Just as biologists can better understand the rain forest by understanding the life cycles of certain parasites, astronomers can better understand the cosmos by tracing the sometimes odd and unusual life cycles of the stars and the galaxies they live within.

Using the INTEGRAL satellite, astronomers discovered 20 new binary systems that consist on neutron stars orbiting supergiant stars. These findings were presented by Dr. Sylvain Chaty (University Paris 7 / Service d’Astrophysique) at the first GLAST Symposium in Palo Alto, California. Using multi-wavelength observations, he and his team identified 20 sources of X-Ray light, and then did followup observations in optical and infrared light using ESO facilities (image above, credit: Paris 7). The IR and optical observations showed that the X-Rays originated from neutron stars passing through clouds of material surrounding super giant stars. The super giant stars 30 times the mass and 20 times the radius of the sun, and are at a stage in their life when they are puffing off roughly one Earth mass of material per year. This material forms a circumstellar cloud around the supergiant that blocks the majority of the giant stars light from reaching us here on Earth. Instead of a giant star, what we see is a cloud of hot dust and gas radiating in the infrared. (all warm things – including human readers of this blog – emit thermal energy in the form of infrared light). When a neutron star enters this gas cloud, its extreme gravity compresses and heats the gas around it until the material emits X-Ray light. In some of the observed systems, the neutron star’s entire orbit keeps it within the gas and dust cloud. In other systems, the neutron star’s orbit is shaped more like the orbit of a comet, and it spends some of its time in the cloud emitting X-Rays, and other time outside of the cloud. There is a really neat movie of this available on Chaty’s website.

In a second announcement at the same GLAST Symposium, a team of astronomers who operate the High Energy Stereoscopic System (HESS) in Namibia described how gamma-ray light can now be convincingly associated with star forming regions that contain massive young stars. These stars, Wolf-Rayet stars, are some of the highest mass stars known, and they live very short lives that are punctuated with a supernova burst and the formation of a black hole or neutron star. The HESS team found diffuse X-Ray emission surrounding a binary system of two Wolf-Rayet Stars. This system is the highest mass binary system known. The diffuse gamma rays come from an area roughly 28 pc in diameter – these is several 1000 times greater than the separation between the two stars! They suggest that the gamma-ray emission may be created by when accelerated particles from the high-energy region around the binary interacting with slower moving materials from the star forming region surrounding the binary. In this scenario, the binary Wolf-Rayet stars blow open a blister in the star forming region in which they reside. Particles within these region are shocked and accelerated. At the skin of the blister, surrounding material is able to leak in, and when it collides with the higher energy particles it is shocked into emitting gamma rays. This scenario has theorized for for a long time and was detailed in 1997 by Whiteoak and Uchida, but this is the first time all the pieces – gamma rays, Wolf-Rayet stars, and a star forming region – have all been found together.

So, what about the lobster? Currently we live during a period biologists refer to as the Holocene extinction. This is an extinction event that is largely driven by man. As we eat things, build things, and chemically treat thing we are killing off vast numbers of animals. It (may have) started with the wooly mammoth, a favorite cuisine of early man, and it continues today with sharks, sword fish, and modern elephants. I could continue my “We’re killing our planet” tirade, but others do it more effectively (see here, here, and here). So, back to the lobster. In a world where so many species are dieing off, it is really cool to find a new type of lobster, and indications that in the Philippines there may be 1000s of new critters just waiting to be classified. And, on a morbid note, each critter we find is one more critter whose genetic structure we can collect and save. Several groups have suggested DNA should be collected from as many life-forms on earth as possible so our planet can someday be re-populated with lost species. Admittedly, this would require cloning, and science still doesn’t know how to clone things consistently, but . . . You can’t clone species you don’t have dna for, so, I’m all for freezing genetic samples.

So, another day, another addition of species not covered in a text book that increase the diversity of our universe. Go science, go.

Today’s press conferences spanned a wide gamut, talking about everything from dwarf galaxies to disk formation to, I kid you not, hot chocolate. The highlight for me was the press conference on new supernovae results. As often happens at these things, three very different results on the same broad class of objects were presented together.

In brief:

• Dr. Stephen P. Reynolds (North Carolina State University) presented results obtained using the Chandra showing that Kepler’s Supernova Remnant (see image above, credit NASA/ESA/JHU/R.Sankrit & W.Blair) resulted from a Type Ia supernovae (the type of supernova created by an exploding white dwarf). In this case of forensic astronomy, they learned that it is possible for exploding white dwarfs to be surrounded by the type of circumstellar material normally associated with higher mass stars going through a period of mass loss via stellar winds. This implies that perhaps larger mass stars are able to loss enough mass to become white dwarfs. If these stars occur in binary star systems, they can gravitationally steal mass from a companion star until they become so fat they explode as supernovae. It has been unclear for a long time what limits there are on which stars can become white dwarfs. We can say with certainty the sun will become one because it is so small there are no other options. This is true of everything up to a couple solar masses. Above this limit however, it is possible for a star to become a neutron star or perhaps even, for the largest stars, a black hole or a supernova that leaves behind nothing at all. ‘Possible’ and ‘certain’, however, are words with different meaning. Now it appears that some larger than previously expected stars are becoming white dwarfs. This has the neat implication that type 1a supernovae may have been able to occur earlier in the universe than was previously expected, allowing Iron, which is created in the explosion, to get distributed around the universe earlier than expected. This means planets may have been able to also form earlier than expected. And, that means, life may also have been able to start forming earlier than previously expected. I’ll explain why that is cool in a later blog entry.
• Dr. Nathan Smith (University of California Berkeley) reported on the discovery of 3 luminous blue variables (LBV) that have surrounding ring structures similar to those seen around the famous Supernova 1987 A. In pre-supernova images of this star it was discovered that SN1987a’s progenitor star was a LBV. This result was a bit shocking because LBVs were supposed to go through a red supergiant phase before going SN, and no one was quite sure how to explain this discrepancy between theory and data (and some really Rube Goldberg theories I won’t go into were made up to fit the situation). The three LBVs that Smith and the research team he works with discovered all resemble SN 1987a’s progenitor (see image at right of HD168625. credit: NASA, JPL-Caltech, Nathan Smith/UC Berkeley), and they believe that perhaps stellar evolution has a never before suspected branch, and that in certain situations LBVs just go supernova. This adds a new branch to the possible paths of stellar evolution, and this result also has neat implications for the future of the nearby LBV Eta Carina. While it was previously believed this star would have to go through one more evolutionary stage before it exploded (becoming a Wolf-Rayet Star), it is now believed Eta Carina may just explode. Boom. While not harmful to life on Earth, this explosion could destroy all the satellites around our planet. While I’d love it if Eta Carina exploded in my lifetime, I have to admit the economic implications are a bit scary. (And it will be hard to study if all the on-orbit observatories bite the dust.)
• Dr. Nicolas Flagey (Institut d’Astrophysique Spatiale, Orsay, France) discussed how the beloved “Pillars of Creation” in the Eagle Nebula may actually not exist anymore. The Eagle Nebula is located roughly 7000 light years away. They have found evidence that in the year 6000BC a supernova exploded, sending shockwaves through the nebula. They estimate the shockwave encountered the Pillars of Creation in 4000 BC, causing them to crumble apart, with the densest material forming stars while the less dense material was dispersed by the shock. Because of the travel time of light, that original supernova may have been observed in 1000 AD, and in roughly 3000 AD future astronomers will be around to find out if this papers results are correct, as they do or do not observe the falling of the pillars. Today we see the supernovae shockwave as red in the image at right (credit: NASA/JPL-Caltech/N. Flagey (IAS/SSC) & A. Noriega-Crespo (SSC/Caltech))

I’m sure that Phil Plait, an expert on SN1987a, will be blogging about the results later, so keep an eye on Bad Astronomy.

In a completely separate press conference, Dr. Michael Ireland (CalTech) announced that it has been discovered that the giant star Mira, a favorite variable for amateur astronomers, is contributing to the formation of a disk around its companion star. As material streams off of Mira, lost to its stellar wind, its companion gravitationally pulls it into a disk. This may be a new way to create a new planetary disk in an old system.

And here is where I admit that I missed the earliest press conference of the morning because I had a breakfast meeting with Dr. Sarah Maddison of Swinburne Astronomy Online. She is a great lady and we did a great little interview, but it means I missed a bit of news. Luckily, one of the other reports, Govert Schilling, was there to cover it. Check out his story at Science Now.

There is so much more I want to write, but there are also people to interview, and I can’t do both at once, so this is it for now.