Monday, January 30, 2012

Game of Thrones Season 2 Trailer

Everyone is talking about it: the trailer for season 2 of Game of Thrones is out. The season premiere is April 1 for the US, at least. Here is the YouTube video for those few who haven't seen it yet:

Season 1 neatly covered the events in Book 1 (A Game of Thrones) of A Song of Ice and Fire by George R.R. Martin. I'm sure all of us hope that season 2 will be likewise faithful to the second book- A Clash of Kings. Even if there are substantial differences, I know HBO will produce an amazing second season worthy to watch and remember.

Westeros has screen grabs from the trailer with comments on what we are seeing.

Saturday, January 28, 2012

Solar Activity

Over the past few weeks I've heard a bit of talk on the Sun and its recent activity. So I figure I'd give a short description of what's going on.

Why is the Sun active?
Most of the time the Sun sits there quietly producing light. However, from time to time, parts on the surface of the Sun will suddenly increase, or flare, in brightness. A lot of light, usually in the form of ultraviolet (UV) and X-ray radiation is produced, but charged particles like electrons, protons, and other ions are also ejected in these events. Flares occur when charged particles are accelerated with the help of magnetic fields in the region. The amount of energy involved is huge, at least thousands of times the entire nuclear arsenal in our planet, and produce the high energy light that we see and accelerate particles that travel 150 million kilometers before reaching the Earth. These flares occur in sunspot groups on the surface of the Sun.

Sunspots are so called because they appear darker than the rest of the Sun. They are much cooler than the rest of the Sun with temperatures of order 3000 Kelvin (2727 Celsius, 4940 Farenheit). In comparison, the rest of the Sun is about 6000 Kelvin. So to say that they are 'cool' is only relative- the surface, or photosphere, of the Sun is quite hot whether or not you are in a sunspot. These spots are actually quite large, the smallest are about the size of the Earth, with many being many Earth-diameters across. The Sun is absolutely huge when compared to our planet: just over a hundred Earth's would be needed to span the Sun's diameter. These sunspot groups are the sites of strong magnetic activity and can lead to flare events or coronal mass ejections (similar explosions that eject a large amount of material out to space). Here is a satellite ultraviolet image of the solar flare event that took place January 27, 2012:
Notice the solar flare on the upper right edge of the Sun. Photo: NASA / SDO / Helioviewer.org.
See a video and discussion here.

One thing to bear in mind is that the Sun has an 11-year sunspot cycle. At some times we are at solar minimum with very few sunspots and associated activity (like solar flares). At others, we are at solar maximum and can expect lots of sunspots and flares. The peak in solar activity was supposed to occur sometime around 2011, but the cycle can be a bit irregular. It looks like now things are starting to warm up and we can expect a peak in activity around 2013 and 2014.

How does this affect the Earth?
During a flare event, UV and X-ray emission is produced. However, compared to other stars (see below) this isn't a huge amount. Also, the Earth's atmosphere is very good at blocking this high-energy radiation. You've probably heard of the ozone layer. This is a layer in the Earth's atmosphere which serves to stop most of the harmful UV light from reaching the surface. In fact, when astronomers want to study stars or galaxies at these wavelengths they have to use satellites in order to avoid the blocking effect of Earth's atmosphere.

However, in addition to the light there are also high-energy particles- protons, electrons, and a few small nuclei, that are produced. As these are particles, they cannot travel at the speed of light and take a bit longer, usually a few days, to reach the Earth. When they do, they encounter two things around the Earth- the magnetosphere and the atmosphere.

The magnetosphere. The blue depicts magnetic field lines surrounding the Earth, in greenish yellow are the charged particles from the Sun. Credit: NASA

The Earth is surrounded by a magnetic field, what we refer to as the magnetosphere, produced in the interior of the planet. Many of the solar system's planets, and even some of the moons, are known to possess these magnetic fields. These magnetic fields interact with charged particles (protons, electrons, etc) and deflect their paths. Some of these charged particles become trapped in the magnetic field and are channeled to the north and south magnetic poles. There they slam into the Earth's atmosphere.
The result, is the aurora. The impact of the charged particles on oxygen and nitrogen atoms cause these to emit light. Because of the magnetosphere's influence, though, these lights only are seen near the Earth's poles and so are generally called northern (or southern) lights. Or in more technical terms- the aurora borealis and aurora australis. During very strong (and rare) solar flares, these may occur much farther from the poles and be visible at latitudes closer to the equator.

The aurora borealis above Bear Lake, Eielson Air Force Base, Alaska. Photo by Senior Airman Joshua Strang.
The aurora are harmless and serve to remind us that life on Earth is protected from these cosmic events by a variety of mechanisms. The same, though, cannot be said for electronic equipment. Satellites in high Earth orbit are not as well protected and can be damaged by the incoming particles (the same would be true of astronauts far from Earth). If you know something of electromagnetic theory, you'll remember that a wire passed under a magnetic field will have a current induced on it. A strong solar storm will induce currents on electric grids on Earth, which can destroy power transformers and cause widespread blackouts.

Flares on Other Stars
Other stars also experience flares, particularly low-mass stars or young ones. As mentioned before, the mechanism behind producing such activity is tied to the magnetic fields at the surface of the star. The mechanism that controls the strength of such fields involves the rotation of the star and the convection going on in the outer layers. Well, it turns out that stars rotate faster when they are young and they continuously slow down as they age. Also, stars of lower mass have much larger convective envelopes. In fact, once you get below a certain mass, the entire star is fully convective. There is indeed a class of star, flare stars, that are known to undergo these events quite frequently. They can also be more energetic than our Sun- the energy released in a flaring event can be about a hundred times more than that released by a Sun's flare.

One particular project I've worked on is the search for young, low-mass stars. We make use of precisely this mechanism to search for candidates: young, low mass stars should be bright in UV and X-ray light. By looking at X-ray and UV source catalogs we can identify nearby stars that exhibit too much emission and can observe them in more detail to figure out what's going on. In many cases, these turn out to indeed be young, low-mass stars. Why is searching for young, low-mass stars important? You'll have to wait for a future blog post to find out...

What does this imply about life around flare stars?
This is actually a big issue in ongoing discussions. Lower mass stars are more common than higher mass ones. An active area of research is to figure out how often planets form in stars of different masses. Most initial studies focused on solar type stars, but we've since expanded to searching for planets among lower and higher mass stars. Even without a good handle on frequency of planets as a function of stellar mass, though, one would still expect that many planets could be around potentially active, low mass stars.

More telling, however, are the requirements for life around these worlds. In order to have life similar to that of Earth's, water is a key requirement. However, these lower mass stars do not produce the same amount of light as the Sun. Hence, a planet would have to be much closer to the star in order to be warm enough to have liquid water on it's surface. That certainly can happen, but we're considering stars that can potentially flare up and release X-ray and UV radiation much stronger than that of the Sun's. Being so close to the stars, these potentially habitable planets would be frequently bathed in this energetic radiation. The outcome is unclear: perhaps this will just drive the rate of mutations of any organism there or perhaps this will sterilize the world of any life. A further complication is that by being so close to the star, the planet may be tidally locked so that one side faces it all the time (similar to how the Moon always show the same side towards the Earth). It's not clear if life could develop and survive in such a scenario, but it's an interesting concept to think about.


For some continued reading on the Sun and some cool images, check out:


Monday, January 23, 2012

Santiago a Mil: El Encanto del Rio Amarillo

Santiago a Mil is an international theater festival that's been going on in Santiago (and a few other cities in Chile) for the month of January. This past weekend was the end of the festival and I had the chance to go see Titanic (see my thoughts here) and El Encanto del Rio Amarillo (The Charm of the Yellow River).

Sunday evening I set out to the Parque Araucano, which is not too far from where I live. This is the first time I went there, but it was not difficult to find and the stage was under a big Santiago a Mil balloon. I'll have to check out the park more carefully in the future. What I saw looked nice, but I hear there's also an aviary and rose garden. Also, I saw a family of bears with Coca-Cola:

But enough about the park. What I went to see was a performance by the Shanxi Song and Dance Troupe. This was a set of 12 dances and songs typical of the Shanxi province in northern China. It's sort of fitting considering the Chinese New Year started on Monday January 23, hence this was like a New Year's Eve.
There were plenty of seats at the park so it was more comfortable than the Titanic showing and the stage was high up so everyone could see. However, the music was a bit loud and slightly painful for the high-pitched instruments. I had a mild headache by the end of the (slightly over) 1-hour show.

We were given a program with the twelve parts, so I'll just go over each part with my opinions and pictures/videos. Remember that you can click the pictures to see them larger and that videos on YouTube also can be seen larger. The videos aren't too long and are only meant as a preview to emphasize what you missed.

First up: Tambor y Danza Oriental (Oriental Drum and Dance).
Nothing really stands out about this one in particular. Many of the dances and music performances were either about the harvest (or farming), about weddings, or just about being happy.

Second, was a solo drum performance by Cao Yan. Here's a video of part of it:
This was quite impressive. Parts were excruciatingly slow, but others were so fast I thought he would break the sticks. This was supposed to be about harvest, but I don't see how.

Next up was Linterna Roja (Red Lantern), which I think of as the main piece of the show:
Lots of happy girls jumping around with their lanterns. Santiago a Mil has an official 5-minute recording you can see here.

The next one, I could have done without. This was Rio Amarillo-Nuestro Rio Materno (Yellow River- Our Maternal River).
The man in blue-green on the left is playing the suona. What the video fails to capture is that this went on for 7 minutes, making it one of the longer pieces. The blaring of the suona for that long gave me a mild headache that did not improve with the following performances. I saw some people covering their ears. The music was really too loud and not helped by the suona.

Disfrute del Yangee (Enjoy the Yangge)
If I hadn't recorded this video I would have no memory of this one. This was one of the few pieces with vocals in the music. 

Next was a two-piece music performance. A solo of the erhu performed by Liu Hongshu.
My video captures the first part: Caballos Galopando en la Llanura (Horses Galloping on the Plain). My only regret is that this isn't really a solo: there's a pre-recorded orchestra in the background. That makes identifying the erhu much more difficult. Still, it was nice and fast paced. At the end, the musician actually make the instrument neigh like a horse. Impressive.


The following was one of the many wedding pieces: Al Compas del Tambor (To the Rythm of the Drum):
The drummers were all joyously jumping around and playing pranks on the bride and groom.


Another wedding, but more unusual: La Boda del Raton (The Rat's Wedding):
This was not a dance, just the 5 musicians performing. It was actually quite nice, a few parts reminded me of the music of the anime Mushi-Shi, which is one of my favorites series. At the end, a cat shows up (ie, one of the musicians 'miaus') and the song ends.


La Camara Nupcial (The Bridal Chambor) was the next piece. No good video, but I have a picture.:
This is what goes on when the bride and groom meet to consumate their (pre-arranged) marriage. The guy was all excited and quickly got into the proper attire. The girl was a bit shyer and it didn't help that she was wearing 3 or 4 shirts. Here she is trying to hold on to the first shirt. It was actually a pretty funny piece.

We follow that with one of the harvest-related dances. Cantaros de Comida (Food Jars)
This depicts the women bringing food to the men working out in the fields. However, with all the dancing around they do the food would have gotten cold by the time they reach them...


Next up is (yet another) wedding piece: Cancion de Boda (Wedding Song). No video, just a picture:
What's that in the table? Why yes, it happens to be some Chilean wine. It is declared good and the music continues. It's a bit ridiculous in that the two main musicians use funny sounding instruments and then their own voices to make very high-pitched, cartoonish noises as they argue.

And the last piece of the night harkens back to the Yellow River with Tambor del Rio Amarillo (Drum of the Yellow River).
One of the best parts, which I alas did not capture, was when they lined up and did a wave with their cymbals. It was like a river flowed through the stage.

And it's over and the musicians and dancers bow before the audience.

Overall Impression
It was a nice show. Some pieces were very good, others, not as much. I did have a mild headache from the loud, high-pitched music, but nothing too unbearable. It was worth it to go (it was free) and was a fun way to spend the evening. This (and a few separate plays throughout town) officially marked the end of Santiago a Mil, though this group would go on to perform on a few other cities in Chile.

I will definitely pay more attention to Santiago a Mil when it comes along next year and I encourage anyone in Chile during January to do the same.

Sunday, January 22, 2012

Santiago a Mil: Titanic

Last night (Saturday, Jan 21 2012), I attended a showing of Titanic, as part of Santiago a Mil. Santiago a Mil is an international theater festival that takes place in January and primarily in the city of Santiago. Plenty of performances are given, some free some not, but I was busy and didn't get to it until the last weekend. Still, the show I saw was fantastic.

Titanic was produced by the German group Theater Titanick and tells the story of the famous voyage across the Atlantic. You can see some information here, but the be warned that the website is in Spanish. The event was held at the Plaza de la Constitucion, which is where La Moneda, the presidential palace, is located. It started at 9PM, but I got there about half an hour earlier and picked a great spot to see the show. I believe it was recorded and passed on to local TV as well, but nothing beats the experience of seeing it live. I took some pictures and some videos and I'll include them below as I describe what went on.

Here we go, the show hasn't started, but people are gathering at the Plaza for the Santiago a Mil festival.

My view of the stage:
I latter stood up to see better (as everyone was doing), but you can tell I had a good spot. The stage is not built yet, as the first part of the show deals with the construction of the Titanic.

Here is my video on (part of) the Titanic's construction (Remember that you can see these videos larger or full-screen at YouTube):
This is less of a play and more of a show. There were plenty of pyrotechnics (see below), music, and lots of action with very little dialog. However, you can still tell what's going on.
Here we're seeing some of the engineers goofing around as they move the wheel into position. Despite the serious nature of the event, there were plenty of light, humorous moments like these.

The Titanic is fully built and sailing across the Atlantic. Notice the streams of water near the bottom (the bow); this ship is going fast. Unfortunately, I cut off the video right before they hit the iceberg (you can hear the music start to change).

Here is a picture, moments after the hit the iceberg:
You can see the engineer at the bow of the ship working to stop the water coming in.

Here's video #3:
The nobles among the ship are feasting and dinning, oblivious to what's going below decks. The engineer is still working hard (and alone) to stop the ship from sinking.
While this scene was lighthearted, I still felt sad. Instead of focusing on the problem, the rich and powerful just ignore it and hope it goes away, while the poor suffer through it.

Eventually, even the folks topside realize things aren't going well:
Signal fires are lit and flares (fireworks!) are set off. Let's hope some nearby ships stop these and don't think we are just partying. Like I said: plenty of pyrotechnics going on in this show.

One last call for help:
This are looking really bad on the Titanic. The crew takes these signal fires to try to call for help, but, as we know, this does not help them.
The fire-net they raise near the bow is over exposed in the video, here's what it actually looked like:
I assume this was just another way to signal the ships, though it could represented the fires going on below decks as things have gotten out of control.

And finally, after just over an hour, the Titanic sinks:
The stage is dismantled before our eyes (with lots of fire and water effects). The wheel crushes the engineer (alas, not depicted in the video), and the smoke stack catches fire. Everyone dies.

Here's the ruins of the set, at the end of the show:


Overall Impression
This was a fantastic show. Practically no dialog, everything is told by the characters interactions on set. The set itself was amazing: it gets constructed and dismantled on-show as part of telling the story. The show touches on the blind faith in technology and briefly on the disparity between the social classes. Lots of special effects (fire, water, music) make this a memorable experience. I would highly recommend any Santiagians catch the final show Sunday Jan 22.

Update: the following day I went to see El Encanto del Rio Amarillo. You can read my summary/review here.

Friday, January 20, 2012

Book Review: The Path of Daggers by Robert Jordan

The Path of Daggers is the 8th book in the Wheel of Time series and as such is very difficult to review for it's own merit. I have been re-reading this series, but had stopped for some time.

Overall Impression
This is yet another good book in the Wheel of Time series. Being nearly in the middle of the series (book 8 of 14) means that it still plods along tidying up some plot lines and adding new complexities. The book itself is fine, but it feels incomplete by itself. You really need the prior and future books to really get at the story.
The plot section in this review will have some spoilers on the story up to this point. The characters are the same ones we've grown to love, though this book focused more on the women- Egwene, Elayne, Nyneave, and Aviendha feature prominently. Rand and Perrin do have viewpoints, though, and their plot lines advance too. As always, Rober Jordan features very strong women, a natural consequence of the world building. Hence, the women's thoughts can seem progressive and modern when placed in a middle-ages type world.


Plot
Spoilers in this section.

When I first read the Wheel of Time series, I went very fast going directly from one book to the next. Hence, I have a hard time remember which events took place in which book.
Last book (or was it two ago?), we saw the girls acquire the Bowl of Winds in Ebou Dar. In this book, we see them finally use it to fix the weather. This is the event depicted in the ebook cover, which is the version I used. We also see the assimilation of Illian into Rand's 'empire' after the battle with Sammael in the previous book, his attach against the Seanchan forces on Ebou Dar, and the attempt on his life by the Asha'man. A lot of pressure is on the Dragon Reborn to coalesce his forces and ready for the Last Battle, though that is still many books away. Perrin is a cool character, but I always felt his plot to be a bit dull (at least compared to Mat's and Rand's). I just don't care that much about the Prophet and Faile. It's impossible for me to recount here all the tiny, but significant, plot events that occur in books like these.

Characters
Part of the book focuses on the girls and some of the Aes Sedia, but we also switch to Perrin and Rand in their separate plot lines. Rand has started getting harder and harder, an ongoing process for the next few books, the consequences (and resolution) of which we learn in The Gathering Storm (Book 12). Egwene finally starts to get some respect, but she still has a ways to go.

One particularly thing I like in this series is that the character's style of speech is clearly distinct and heavily influenced by their country of origin. Very subtle changes in word order or in phrasing sentences go a long way to establish these patterns. The Illianer way of speech do be one of my favorites. Taraboners, they also possess a unique style, yes?

Setting / World Building
This is a Wheel of Time book, so the setting is already well established. We know the countries and how the magic system works. At this point in the series very little is being introduced, though we do get some more insight into the Warder bond and learn of the difficulties on learning second versions of weaves you are already familiar with. We also learn some interesting tidbits on Callandor and can see the gears moving in Rand's head about saidin and the most powerful sa'angreal.

Final Thoughts
Another fine addition to the Wheel of Time series. It is not my favorite, but it does have some cool moments. It's very difficult to judge a book like this on it's own worth since it depends so much on the prior books and promises so much for books to come. I'll be continuing my reread, but with many other books between these.

Next up is a break from epic fantasy by reading Anathem by Neal Stephenson.

Wednesday, January 18, 2012

Chilean Anti-Sunset: 1/18/2012

A few weeks ago I posted this horrible picture of the Eastern view from my apartment:

This was around sunset, but the Sun sets in the west, so it's more of an anti-sunset picture. The picture fails to capture the eerie red glow from all the haze and smog (and clouds).

Today, I am pleased to offer you a similar view at about the same time of day:

As you can probably tell, conditions are much better. There's been some wind today and the views are very clear.

SOPA: Stop Online Piracy Act

As you have undoubtedly heard by now, many websites on the internet, including Wikipedia, were blacked out today in protest of the Stop Online Piracy Act (SOPA) and the Protect IP Act (PIPA). The goal of the bill is to go after pirates distributing copyrighted material, however, the provisions in the bill severely encroach on freedom of speech liberties. Basically, it allows for the censorship of websites and material on the internet.

I'll direct you to a few places to get more information:
Here's a good summary of what's going on with ways on how you can sign up against SOPA: http://americancensorship.org/
Here's a great video explanation.
Here's some more information as well.
And here's the Wikipedia article on SOPA and Google's End Piracy, Not Liberty page.

I am opposed to the bill, but as a citizen abroad I'm not sure how well I am represented. Still, it's good to hear that my comrades in the States are also against this and have been calling their representatives to make their voices heard.

If media corporations want to fight piracy, here's what I suggest: provide affordable alternatives worldwide. You remember back in the day when people would download music illegally? Well, if you want some music now, you can use Amazon, iTunes, and a number of other services to get your music legally and reasonably priced. With easy alternatives like that, there's no incentive for average people to resort to piracy.
Ideally, this should also extend worldwide. Our society has become globally connected, we hear about news and events from all over the place and can talk to people across the planet in an instant. Yet it is annoying when I go to Hulu and find out I can't watch some TV episodes because I am in Chile. The reasoning behind this is copyright restrictions on different countries. Perhaps when you start having piracy problems, these corporations should look to the source. I would say the solution is not to tighten your grip and lash out at your consumers, but to explore new ways to release your products.

This is part of some drastic and alarming changes taking place in the US ever since 9/11. It's as if people collectively (or, perhaps more accurately, those in power) are afraid and are happy to give up freedom and basic rights in exchange for a little safety. Remember the days when you didn't have to take of your shoes at the airport to board a flight? It seems to me that rather than 'innocent until proven guilty', we've been changing it to 'assume they're guilty... just in case'.
While this isn't 100% related to SOPA/PIPA, I think all of these things are pointing to a very dark future ahead of the US in terms of civil liberties. I recommend reading 1984 by George Orwell, to see how a heavily censored police state works.

Sunday, January 15, 2012

Planets in Binary Star Systems

The Kepler space telescope has been staring at a patch of sky to look for the dimming of light when a planet passes in front of a star. One of the interesting results coming from Kepler is the discovery of planets orbiting pairs of stars, more commonly known as binaries. These circumbinary planets are exciting because star formation tends to produce stars in pairs or groups. These binary stars are common, so finding planets among them is encouraging as it suggests planetary systems are also quite common. In this blog post I'll talk about some of the recent Kepler results and prior research on planet formation in binary star systems.
The Kepler-35 system. Credit: Lynette Cook / extrasolar.spaceart.org

How do planets form?
Planets are believed to form in gas and dust disks around stars. When we first started thinking on how the Earth and the solar system formed we realized that all the planets lie roughly in the same plane, what we call the ecliptic. The big planets were far from the Sun, whereas the smaller ones were close in. We developed the disk hypothesis to explain this scenario. Here's how it goes: the early Sun was surrounded by a disk of gas and dust. The material in the disk was used to form planets, but far from the early Sun the disk temperatures were low allowing many ices like water ice and carbon dioxide ice to exist. This facilitated the formation of large planets like Jupiter and Saturn, whereas close to the Sun the disk lacked these ices and the planets, like Earth and Venus, ended up smaller. Since the planets all formed from the disk, they all share the same plane, similar to the rotation axis of the Sun, all as a consequence of conservation of angular momentum.

This picture is nice and simple, but it has been challenged since we started finding planets in the mid-90s. One of the first problems was that most extrasolar planets (or exoplanets) orbited very close to their stars, but were very massive. These 'hot Jupiters', as they are called, have masses comparable to that of Jupiter in our own solar system, but orbit much closer than Mercury is to the Sun, whipping around their stars in a matter of days. For comparison, Mercury takes 88 Earth-days to go around the Sun, whereas Jupiter takes about 11 Earth-years. These hot Jupiter are very easy to detect and so were the first such exoplanets detected. We've revised the disk model of planet formation to include things like planet migration, where planets form far away and drift inwards, to explain how these objects form.

The HAT-P-11 system.
Credit: Subaru Telescope,
National Astronomical Observatory of Japan (NAOJ)
More recently, we've started to measure the plane of exoplanet orbits relative to the spin axis of their stars. We expected these to be aligned, but much to our surprise some systems are very different or are orbiting in the opposite fashion as the star is spinning. This again challenges the simple disk model I outlined in the first paragraph. Planets migrating inward wouldn't change their orbital plane, so perhaps dynamical interaction between multiple planets is more important here.






As more and more planets are discovered, we find new ways to challenge our models. This is how science grows: we develop a model, test it, and refine it, continuing until we can satisfactorily explain the phenomenon we observe. Here's one other system that's difficult to explain:
The Kepler-20 system. Credit: David A. Aguilar (CfA)
Kepler-20 depicted above hosts 5 planets, but the radius and masses of these cycle between big and small rather than having all of them nearly equal size or having them segregated by mass. This is yet another scenario that challenges our ideas on planet formation.
But enough about planet formation, let's talk about binaries.

What do we know about disks in binary systems?
Many young stars possess these gas and dust disks, also known as protoplanetary disks. Furthermore, roughly half of all stars are in binary or multiple systems. These systems possess more than one main star and the secondary star(s) will influence the formation and evolution of any other objects in the system.

Theoretical and numerical studies suggest that secondary stars will disperse protoplanetary disks as the gravitational influence of the secondary creates gaps or truncates the disks. This has also been seen in observations. Studies of binary protoplanetary systems do show lower disk masses than around single stars and more widely separated binaries. The cutoff appears to be in binaries with separations of 100 astronomical units or less. An astronomical unit, or AU, is the distance between the Earth and the Sun and corresponds to about 150 million kilometers. This defines the scales for studies of planetary systems and disk studies. For comparison, in our solar system Mercury is at 0.39 AU and Neptune is at 30 AU from the Sun.

My own research has dealt with debris disks, which are older disks on planetary evolution timescales. I wrote a brief blog post about debris disks some time ago. They also show similar trends as the younger protoplanetary disks and are consistent with the theoretical picture. Most stellar binaries have separations of order 20-40 AU and would very readily disrupt any disks forming in the system. If a planet is to form in a binary system, the two stars must be very widely separated (hundreds of AU) or very closely separated.
The V4046 Sgr circumbinary disk; the two stars are 0.04 AU apart. 
Credit: David A. Aguilar (CfA)

Are any planets known in binary systems?
This is the big question and we already know the answer to it: YES. While many studies avoid searching for planets in binary systems (due to the complications these pose), about 10-20% of planet bearing stars have a more distant companion. These companions tend to be very widely separated so it's unlikely that they have influenced the evolution of the system in any significant way. For a long time, it seemed that the secondary stars were at least 20 AU away from the primary, and more usually at least 100 AU. However, there were a few cases were circumbinary planets were announced. These only increased in number with Kepler.

Circumbinary planets and Kepler results
A handful of circumbinary planet candidates were known prior to Kepler. These were discovered by looking at eclipsing binaries and accurately timing the eclipses. If you understand the system well, you can accurately predict when one star or the other passes in front of, or eclipses, the other. However, in a few cases the eclipse did not occur at the expected time. There is a discrepancy between the observed and calculated eclipse time which suggest something else is in the system. An unseen planet, for example, can tug on the stars and mess up the timing. This is an indirect probe of the system, as the planet is not actually observed.

Kepler searches for planets by staring at stars and monitoring how bright they are. When a planet passes in front of the star, or transits, the star will become slightly fainter. Kepler has detected thousands of candidate planets and many of those are being confirmed as true planetary systems. One particularly exciting planet system, in my opinion, is Kepler-16, depicted below.
The Kepler-16 system. Credit: NASA/JPL-Caltech/T. Pyle
Kepler-16 was the first case where a planet was seen to transit two stars, which also mutually eclipse one another. This is undeniable evidence for a circumbinary planet. The two stars are separated by only 0.2 AU, but the planet is more than 3 times farther away with an orbit at 0.7 AU. The system is quite compact, but the stars are smaller than the Sun so the temperature of the planet (and any moons) is likely to be too cold to support liquid water and life as we know it. Since then, Kepler has discovered two more circumbinary planets: Kepler-34b and Kepler-35b. It looks like circumbinary planets aren't so rare after all!

While more and more circumbinary planets are being found, we're finding that these follow the theoretical expectations and disk observations. That is, the stars are very closely separated compared to the planet location. Hence, planets like Star Wars' Tatooine, may form out there if a planet-forming disk surrounds a very close pair of stars. Considering the fact that hundred of billions of planets may be in our galaxy (see here), then even with the restrictions imposed by a secondary star, there must be millions of circumbinary planets out there.

Bad Astronomy has an article on the Kepler-34 and 35 systems (also Kepler-16) in case you want to do further reading.


Friday, January 13, 2012

Astronomy: The 219th American Astronomical Meeting

I've now returned to Chile after spending a few days at the largest, bi-yearly, astronomical meeting in the US. This was the 219th meeting of the American Astronomical Society, which was held January 8-12, 2012 in Austin, TX.

This was my first time in Austin; it's a nice city. Lots of good tex-mex and the capitol building was nice to visit:


The AAS meetings, especially in Winter, are extremely large. An estimated 2700 astronomers attended this January. Multiple meetings take place simultaneously, and posters are up all day. Hence, it is physically impossible to do and see everything going on. I personally was running back and forth between some of the sessions to try to hit particular talks. One way to keep track of some of the other talks was to check the twitter feed via the hashtag #aas219. For example, I wasn't at the NRAO session, but still learned the VLA's new name: the Karl G. Jansky Very Large Array.

More important than checking the talks, though, is meeting up with collaborators, friends, and other researchers in the field. I had my own poster on Wednesday, and while I did attend some sessions, the majority of the day I was at my poster talking to 'customers'. I met many great people that day (and throughout the conference) which I knew only by reading their papers.

There were also several interesting research results presented. I wasn't at any of the press meetings, but found out through the web. I list some of ones that interest me as well as links for more information:

  • At least 100 billion planets expected in the Galaxy. Click here for the news.
  • 3 new, small planets detected by Kepler. The smallest is the size of Mars. Click here for the news.
  • 2 new circumbinary planets, each orbiting a pair of close stars. Click here for the news.

This last result is particularly relevant to my research (and the poster I presented) so expect a future blog post on planets in binary star systems.

As I've mentioned already, I was keeping track of the conference via the twitter feed (#aas219). I started using The Archivist, but the output of that is not always terribly useful. The most interesting result from that is the following:

This is a breakdown of the most prolific twitterers using the #aas219 hashtag. I've you've been wondering who to follow for astronomy news, these are good folks to consider.

Also interesting is the frequency of posts (alas without a vertical scale), which clearly shows when the conference was in session:

However, my personal favorite way to visualize the social media's response to AAS is through word clouds. Using Google Reader I gathered all tweets from January 6 to 13th and present here a word cloud generated with Wordle:

I afterwards realized that my copy-pasting may have duplicated some entries, but that should not affect the results too much. I'm only including the 100 most common words after removing a few things like #aas219, RT, and time stamps. For those seeing word clouds for the first time: the larger the text, the more frequently it was mentioned. Note that upper case and lower case words (see Exoplanets and exoplanets) are unfortunately not counted together.
The URLs in the cloud point to the 100 billion+ planets and the smallest exoplanet links I provide above. As you can probably tell, Kepler, exoplanets, and planets are hot topics in astronomy right now. It's possible that Milky Way and galaxy are there because of tweets like "100 billion+ planets in Milky Way galaxy" which really are about planets again.
A few terms are in Spanish (Sociedad, Astronomica) and Xbox refers to the tweets about Steve Hawley's talk which mentioned that the HAL computer on the Space Shuttle was about 0.005% as powerful as an Xbox 360. A few prominent speakers and tweeters (as indicated by the @ symbol) were  also frequently mentioned.

There's a few common words in the cloud regarding the moment of silence held for Steve Rawlings at the meeting. This was done on Thursday after I left, but the news is that this observational cosmologist was found dead Wednesday evening at a colleague's home near Oxford. His colleague, the mathematician Dr. Sivia, was arrested on suspicion of murder, which makes this an even sadder story. Here and here are some of several news articles about it. That's an odd way to end the meeting, to say the least. I did not know Dr. Rawlings, but my thoughts go out to his family and friends.

So that's it for my summary. It was a good conference to catch up with some of my colleagues in the US. It was somewhat overwhelming, but worth the long trip up. My only regret is that, through an unfortunate oversight, my flight left Thursday morning, while the conference was still in session (though on it's last day). I doubt I'll attend the next AAS meeting, despite the interesting locale for the coming Summer session (Anchorage, Alaska), but perhaps I'll get to go to other future meetings.

UPDATE Jan 16, 2012: As mentioned in Astrobetter, @doug_burke has some nice statistics on AAS 219. It turns out I came in as the #62 most frequent tweeter, right at the bottom of the list.


Monday, January 9, 2012

Astronomy: Debris Disks

I figured I'd make a post about some cool things in astronomy, particularly those relevant to my own research. Today's topic: debris disks.

While writing this I realize the topic is far too broad to give it justice, but hopefully you'll get a flavor for what these are and why they are so cool.

Artists conception of HD 98800
Credit: NASA/JPL-Caltech/T. Pyle (SSC)

So what are debris disks? 
The short definition is that these are rings or disks of dust grains surrounding a star. Think of them like Saturn's rings, except on a much larger scale. Read on to learn more.

How can we find these disks and rings?
The trick to finding them, is to look at systems in infrared light. What we see with our eyes is, aptly named, visible light. When you go outside and see your friends, you are seeing visible light from the Sun, the Moon, or nearby artificial sources reflecting off of your friends. In complete darkness you would not be able to see them without some equipment, like heat-vision goggles or infrared cameras.
We humans have a body temperature of about 310 Kelvin (98.6 Farenheit), which means we glow at a wavelength of 12 microns. Visible light, in comparison, has wavelengths of 0.4-0.7 microns or so. Hence we cannot see our own glow without specialized instruments. The peak wavelength an object emits depends on its temperature. A hot object, like a lightbulb's filament or the surface of the Sun and other stars, will emit light near the visible range. Colder objects, like our bodies, emit at longer wavelengths and thus in the infrared and submillimeter range. The dust grains constituting debris disks can be as warm as 300 K, but are generally colder than 100 K. To observe these systems we need to look at light in the 20-500 micron range.

Here is what the sky looks like at 100 microns:
Credit: R. Hurt/IRAS/DIRBE, see here
As you can probably tell, the sky looks very different from what you are used to. What we see is the cool dust spread throughout the galaxy; we barely see any stars at all. The Galactic plane runs horizontal across the image and we can see a few nearby star forming regions- Ophiucus is near the center and above the plane, Taurus is at the left, Orion at the right, and some galaxies- the two blobs below the plane midway to the right are the Large and Small Magellanic Clouds, nearby galaxies to our own Milky Way.

Stars barely produce any light at these wavelengths; their emission peaks in the visible, remember? Hence, we can look at where the stars are supposed to be and see if there is any light at 100 microns (or any other such long wavelength). Sometimes we see that there is indeed light coming at those wavelengths. By looking at multiple long wavelengths (say 12, 25, 60, 100, etc, microns) we can reconstruct what's going on and say 'something of temperature X is present around this star'. As we've learned, this is a disk or ring of dust surrounding the system.

Where does the dust come from?
This is an interesting question as there are two possible answers. The first is that the dust is primordial material, that is, it is left over from the star formation process. This will generally be the case for the very youngest stars. However, stars are very effective at clearing out the system of dust. In only a few thousand years the dust grains should be cleared out, though the timescale depends greatly on the properties of the star, the removal mechanism, and the dust grain sizes. Most stars, however, are hundreds of millions of years old and are not expected to have any material leftover from the star formation process. In this case, the dust we see has been recently (or continuously) produced by collisions of rocky objects. For example, asteroids or Kuiper belt objects, when they collide, will produce dust. If enough of these collisions occur, then a detectable debris disk emerges in the system.

Can we actually see these disks?
In many cases, the resolving power of the far-infrared instruments we've used to find these disks is not sufficient to actually produce an image. What we see is just a blob and can't tell if there is any structure there. However, for the systems closest to the Earth, or those with the largest disks, we've been able to actually produce an image of the disk. In some cases, we can also see the disk in visible or shorter-wavelength infrared light, when the grains reflect the light of the star. This tends to produce some of the nicest images we have.
Here are a couple of debris disks seen with the Hubble Space Telescope:


Does our own solar system have a debris disk?
Our solar system has tons of small objects (asteroids, comets, and Kuiper belt objects). When these collide they produce dust; however, collisions are much less frequent today than they were billions of years ago when the solar system was young. Hence, the amount of dust is minute. Our telescopes are capable of detecting dust in distant star systems if it these contain substantial quantities of dust, say at least 100 times that of our own solar system (though if I recall correctly, the Herschel spacecraft does get close enough to the expected contribution from the Kuiper belt). So detecting an analog to our own solar system from afar is not feasible with our current technology. However, we are embedded in our system and thus have a much closer view. Collisions and comets have produced dust in our system that we can see as the zodiacal light:
Credit: Bob King / Duluth News Tribune
You need to be in a very dark sky to see this triangular wedge of light. You'll spot it right after sunset or right before sunrise. I must admit to never having seen the zodiacal light, though I've been in dark observation sites.

What about planets?
Planets are one of the hottest things in astronomy right now. Everyone is talking about them, especially the public. Debris disks indirectly suggest planets, or at least planetesimals like asteroids, exist or have existed in distant stars. This is encouraging as it's easier to spot debris disks than it is to search for planets. Furthermore, the properties of the disk can suggest a nearby planet. For example, gaps, warps, or offsets in imaged disks or rings can suggest an unseen object (ie, a planet) is tugging the material to produce these features. This was the case for the beta Pictoris star system, where a secondary dust disk was observed in the central regions. A close examination revealed a massive planet in the system:
Credit: ESO/A.-M. Lagrange et al.

My own research:
One particular line of study I've done is to explore how often binary or multiple stars, that is star systems with two stars or more, possess debris disks. It should not come as a surprise that a second (or third, etc) star will disrupt the system. While planets are known to exist in these multiple star systems, they are mostly found around either very widely separated stars, so that the gravitational influence of the second star is minimal; or around very tightly spaced stars, so that the planet effectively sees them as just one object. For intermediate separations, say a second star located at Saturn's orbit in our own solar system, the second star would completely disrupt the disk preventing a solar system-analog from forming.

Finishing thoughts:
Debris disks are cool. They are a by-product of planet formation and their study allows us to explore how planets like our own are formed. As a bonus, they are also really neat when imaged. For now, all we can do for planets is get a tiny point of light, but for nearby disks we can get the whole structure.

I hope to do more of these astronomy posts from time to time, and perhaps to revisit debris disks in a more focused post. Stay tuned for a brief summary of my impressions of the American Astronomical Meeting #219 in Austin, TX.

Friday, January 6, 2012

Book Review: Un Lun Dun by China Mieville


This is China Mieville's first young adult (YA) book. I dislike the classification of books as 'YA' as it seems to me that the only reason is due to the age of the primary character. Regardless, the reason I read this is in preparation for Mieville's new book Railsea, which everyone claims will be YA as well despite the scarcity of information. Railsea and Un Lun Dun have nothing to do with each other, but I wanted to see how Mieville manages YA.

Overall Impression:
China Mieville again writes an excellent tale with a masterful control of language. However, unlike his other books, these one feels more directed. His other works tend to meander a bit, exploring the world (which is cool), but this one gets straight to the point. In a sense, this works quite well.

I was worried his language would be watered down because it's YA and in a way it is (no febrile or puissant here), but there are still many clever creations. Some of the best new words, in my opinion, include binja, smombies, ɹɐɔ, and my favorite: arachnofenestranauts. These are exactly what they sound like.

Plot:
Fast paced action with some very interesting twists on the whole 'quest fanatasy' trope. The chapters are short so it makes for a very quick read, in fact, there is one chapter whose title (The Powerful Resurgence of the Everyday) is longer than the text (Of course she was wrong.).

Without spoiling too much: this is the story of a city Unlike London: UnLondon. It is being attacked by the evil, sentient Smog, but prophecy says a Chosen one will come from London, go on a quest, and save them. In a clever twist, however, Mieville has the sidekick (the UnChosen one, if you will) actually be the hero. She's smart enough to realize the quest is bogus, skips around the prophecy, and manages to save the day. So much for quests and prophecies...

Character:
A binja of Un Lun Dun
Mieville has created some cool and very unusual characters here. The most ordinary ones are the two London girls who visit UnLondon- Zanna and Deeba. The others are UnLondoners of all shapes and sizes ranging from spoken words, half-ghosts, animated rubbish, and monsters of all kinds. One thing I wasn't expecting is that the book is illustrated by China Mieville himself. We get to see how some of the characters and most of the monsters look like (though see below for some fan art). Most of the monsters are neat, but I was terrified at the illustration (and description) of the giraffes. Just like the Londoners I was all like: "Giraffes? Ha! They don't scare me" and then after seeing them: "RUN!!"

The story revolves around Deeba and it's her we get to know best. She starts of very reluctant, wanting to go home right when they arrive, but soon she's the one leading the game and promising she'll be back. She's the most 'normal' character we see, the others are all UnLondoners (though Jones is originally from London) and each one is unique and special.

Setting / World Building:
Every single Mieville book I've read centers on a city. The city in fact, is so very present it can almost be considered a character in itself. I've seen London, UnLondon, New Crobuzon, Embassytown, Besźel/Ul Qoma, and Armada. All of them are very different from one another, but also very well characterized. I have never been to London, so I can't tell how similar it is to UnLondon, though I'm certain the 'Sun' (or more accurately UnSun) is not a disk with a hole in it, the buildings aren't made of MOIL technology (Mildly Obsolete In London), nor is there a bridge whose ends lie literately anywhere and everywhere.

This book, in particular, is not as dark or heavy as some of his other works. The one thing that stands out is the environmental aspect (they are fighting Smog, after all), but I'm not troubled by that.

Final Thoughts:
I like this book. It's classic Mieville, without being gruesome or dark (like Perdido Street Station or Kraken) and with milder monsters. It also has a very nice, definite, happy ending. I still consider Embassytown, The Scar, and The City & The City as my favorites, but this was a good read.

As a bonus, click here for some fan art by IniquitousFish. These are the main characters of Un Lun Dun. It almost looks like you could find these characters in a Professor Layton game or as part of some anime! I especially like the re-interpretation of the utterling Cauldron.


Next up is returning to epic fantasy with my long overdue re-read of The Wheel of Time. Coming up is Book 8, The Path of Daggers by Robert Jordan.
It might take a while since I'll be traveling and attending a conference, so the next few posts may be more Astronomy related.

Thursday, January 5, 2012

Chilean 'Sunset'

This evening, I noticed my apartment was bathed in an eerie orange light. I figured, "that's just the sunset", but there's a problem: my apartment faces East, not West. I see sunrises, not sunsets.
I had a look outside, and this is what I saw:

I'll have to post another picture on some other day so you can see how unusual this is; it's usually far clearer (Update: see here for another, much clearer anti-sunset). This image also fails to capture the eerie glow all over the place.

Now part of that is just clouds coming in from the East over the Andes, but the part near the ground: I'm not too sure. The most likely culprit is smog, as this is extremely common here in Santiago. I've never seen it like this towards the East, though: it usually is worse (and clearly smog) looking West or South as this is where the densest parts of the city are, relative to where I live and work.

Still, it seemed appropriate at the time considering I'm ~70% done with Un Lun Dun, whose bad 'guy' is Smog itself.

Saturn, Titan, and more!

A short post on today's Astronomy Picture of the Day.
Jupiter has always been my favorite planet, but I completely understand why people love Saturn when I see pictures like these:
Credit : Cassini Imaging TeamSSIJPLESANASA

Titan, the largest moon of Saturn, the second largest moon in the Solar System, and a moon larger than the planet Mercury, is in the foreground. Titan is also the only moon with a thick atmosphere, it's even thicker than Earths! The haziness surrounding Titan in this picture is the upper layers of the atmosphere.
About a million kilometers behind is Dione, the third largest moon of Saturn. 
Further back you can see a gray horizontal feature- those are Saturn's rings. The rings are extremely thin and we are seeing them nearly edge on.
On the background is Saturn itself. There seems to be some cloud feature near the mid-left, but the main feature you can see are the shadows cast by the rings on the gaseous surface of the planet.

Big planet, tons of moons, and an impressive set of rings. Yeah, I can see why Saturn is so cool.
I recommend checking out the Astronomy Picture of the Day frequently for amazing pictures such as this one.

Tuesday, January 3, 2012

Favorite Books of 2011

While I don't feel I read a whole lot of books in 2011, according to my Goodreads log I finished 32, including a few graphic novels. In the spirit of summarizing 2011, I present here my favorite five among those books I read. I should note that these are books I read for the first time in 2011 regardless of whether or not they were published that year. I've tried to sort them in order of increasing awesomeness, but I must say I rank all of these quite highly.

5. The Dragon's Path by Daniel Abraham
My first introduction to the work of Daniel Abraham. This is your classic epic fantasy, but somehow it just grabs at you. One particularly interesting thing for me was to see new types of characters that normally don't make it into fantasy, namely the budding, bureaucratic banker. You'd think that would never work, but it does, actually. Combine that with an engaging story and decent setting and you've got a great book. This is the first of the Dagger and Coin series and I eagerly await the upcoming books. In addition, I've added Daniel Abraham's Long Price Quartet to my list of books to read.

4. The Scar by China Mieville
After I discovered China Mieville's work a year or two ago, he has quickly risen to my list of favorite authors, so much so that he appears twice in this list. The Scar is the second book set in the Bas Lag universe, of which Perdido Street Station is the first. While I enjoyed Perdido, I found The Scar to be so much better. The characters, setting, and plot are just outstanding. I particularly enjoyed the character Uther Doul, he is a brilliant swordsman with a potential sword. I want to see him included in one of Suvudu's cage matches, but I guess no luck on 2012.

3. The Wise Man's Fear by Patrick Rothfuss
The long awaited sequel to The Name of the Wind. We continue to learn the story behind Kvothe's legend. The anticipation, like for A Dance with Dragons by George R.R. Martin, probably skewed my views, but that's alright: I feel I enjoyed the book for what it's worth (more so than the equivalent Dance). There are moments of beautiful writing in this book. For example, if you read parts out loud,  the characters sometimes talk in verse! I thought that was clever; it's not an easy thing to do. There's so much left to do, though (at least, in my opinion) that I worry about it being all wrapped up in the next book.

2. Gardens of the Moon by Steven Erikson
This is the first book in the Malazan Book of the Fallen and my only regret is not starting this series sooner. This is epic fantasy at it's greatest and is a worthy addition to such classics as The Lord of the Rings, The Wheel of Time, A Song of Ice and Fire, etc, etc. Great characters, intriguing plot, amazing world. It's still too early for me to grasp everything that's going on, but this is one series I aim to finish. And the good thing: the 10-book story is already complete!

1. Embassytown by China Mieville
When I first heard about this book, I knew it would be good. This is Mieville's first foray into pure science fiction, and he makes it work. Mieville is a master of language and he really shines in this book. It's arguably my favorite Mieville book thus far. The story has 3 arcs: first is the distant past, when the character is young and you learn about the immer, Language, and a bit about the Hosts; following that is an entertaining part where you flip back and forth between the present and the near past; after that is the fast paced section where everything ties together and you get to see the consequences of all actions past. I will be very surprised if I don't see Embassytown getting a Hugo nomination this year.



Monday, January 2, 2012

Book Review: Deadhouse Gates by Steven Erikson


This is the 2nd book of the Malazan Book of the Fallen series.

I had heard many good things about this series. In particular I was told it was similar to A Song of Ice and Fire by George R.R. Martin with the exception that it is finished (10 books) and far more magical.
You can see my Goodreads review for the first book (Gardens of the Moon) here. I finished Book 2 on New Years Eve, but I'll post my review here since it's fresh in my mind.

Introduction

It's a New Year and I decided this is the perfect time to start something new: blogging.
I've been thinking about this for a long time and figured I should just give it a try. There's plenty of blogs out there so this isn't something especially significant, but hopefully it will be my little corner of cyberspace.

First off, who am I?
I am a professional astronomer at Universidad de Chile. I am originally from Puerto Rico and have lived in the US for ~9 years of my life. While I don't intend to share everything here, my background serves as the lens through which I view the world (as it does for all of us).
I may do a more in-depth introduction post later on, if I feel it necessary.

What is this blog about?
Anything and everything that interests me, or that I feel needs saying. In general this will be book reviews, astronomy news, movie or game reviews, life in Chile, or any other curiosity. Though I'll focus on things I like, there may be time I mention those I don't like, such as US politics or Chilean banks.
All articles will be in English, though I may link to Spanish sites if I find the need to comment on them.

How frequent will I post?
That's the tricky question. I can envision being very enthusiastic at first and then getting bored and abandoning this blog, as I've seen some of my friends do. However, I have a plan for this. I read a lot and I write a brief review on Goodreads every time I finish a book. All I have to do is make sure to post my review here and voila, my blog remains active. Last year Goodreads marked me down at reading ~30 books, so not bad ;)

Hence, expect frequent book reviews (generally science fiction and fantasy) and musing on other topics.
Let's hope this blogging thing works out.

- Strakul