Saturday, July 30, 2011

A Look At Our Solar System

I love showing this youtube video about the asteroid discoveries in our inner solar system. Scott Manley takes the positions of detected asteroids, and highlights them as they are discovered. The final colors indicate how close they are to the Earth's orbit:

Red= Earth Crosser
Yellow= Earth Approachers (coming within 1.3 AU)
Green = All Others

The discoveries tend to follow the Earth's orbit because asteroids are best seen opposite the sun, when they are most illuminated. It's also interesting to see that discoveries go way up in the 1990's, when satellites start coming online. This is a cool way to highlight the importance of technological advances to scientific discoveries.

And, if you think this looks like a crowded mess, the Kuiper belt around the outer solar system is about 20 times as wide!

I love videos like this because they are sobering reminders of the vastness of space. As dense as these asteroids look, they won't collide with each other. In fact, movie scenes of spaceships dodging chunks of rocks in the Asteroid Belt is just plain wrong. The Asteroid Belt is mostly made of empty space. Yup. That's right. That's how BIG space is!

In the spirit of the late Carl Sagan, I sometimes think about how tiny the Earth is in this video. I really try to visualize it's place in our tiny corner of the Milky Way. It's just one planet circling one average sun with a half million other chunks of rock. Then, sometimes I think about the wars fought over this planet - the wars of death and human misery that were caused by zealous rulers intent on owning a piece of this tiny rock. You wouldn't be able to see the boundaries we fight so fervently for. Astronomy is, like so many people say, a humbling field. In the grand scheme of things, everything just seems so . . . small.

Thursday, July 28, 2011

How Grad School Differs From Undergrad (In My Experience)

It seems insufficient to say that grad school is way different from undergrad. It just doesn’t seem to communicate the true significance of the change in environment and expectations as the transition is made from one to the other. I guess it really depends on where you came from, and where you are going, but some people handle it better than others. I was not one of those people. I will probably write a bit about why I feel I’ve faltered in some sense with grad school. It’s been on my mind for nearly a year now, and now I think I see things more rationally.

I came from a small undergraduate institution, called the New Mexico Institute of Mining and Technology – or, New Mexico Tech for short. Though most people have never heard of it, this school is actually quite a diamond in the rough. The National Radio Astronomy Observatory (the very same one that runs the Very Large Array) was right off campus. An optical interferometer owned by the school was in its construction phase during my time as a student, which will be built right next to the Magdalena Ridge Observatory. Military money for research was donated in such copious amounts that the school had funds coming out of its ears. Because of that, I was able to earn a college degree with absolutely NO debt. Heck, when I moved off campus, NMT wrote me a check.

Along with being dirt cheap, New Mexico Tech also had the best physics department around. Whereas most people never see their department heads, mine knew I was a member of the Astronomy and Physics clubs without my having to tell him. When it was time to write grad school applications, he sent me his personal proposals (some that were effective, some that weren’t) and edited my essays not once, but three times! Making friends was effortless. I felt so connected to every person on campus, be it faculty or student, that I knew if I ran into any problems, there would people to help me whether I wanted help or not.

Those years were some of the happiest in my life. And perhaps, this is my plea for you to understand why I was so unprepared for the dynamics of a large school.

I assumed every place worked like Tech. Ridiculous assumption, of course, since a larger school simply cannot support such a tight knit community. The biggest thing I needed to learn about grad school, and the thing that new grad students should know, is that your advisor can’t dedicate as much time to you as you may need. Unlike the professors at Tech, they simply don’t have the time for it.

This seems a bit harsh, but in the end, it may be a necessity. My former advisor told me that he was so swamped with work that the only time he had for his own research was Sunday nights, when he supposedly wasn’t supposed to be working at all. Adding the emotional frailty of a self-conscious student with huge confidence issues would be too much. Besides, what was he supposed to say?

In reality, you are no longer viewed as a young undergrad. Grad school is training for a job, and your job is to turn out product (papers) as fast and as efficiently as you can. You cannot earn the respect of other professors or scientists by whining about how alone you feel.

Understand, too, that your project will not be a major focus in your advisor’s life. You will have to deal with untimely delays, and you will have to be the one to search for help when you need it. Nobody will hold your hand through the process.

Then again, would I really want it any other way? How can I become an independent scientist if I’m not weaned from “free” projects?

Please know that I am not ragging on the Astronomy Department here at the University of Arizona. Along with the small growing pains of the first couple of years, there are many more opportunities at a larger university than I would have had at a smaller one. Instead of one colloquium a week, there are many, many more. There are small discussion groups dedicated to specific research topics. One professor gave me awesome advice when searching for an advisor, and another one gave me great criticism on a talk I had given. I’ve even found that when I crossed the street to the National Optical Astronomy Observatory for Friday Social Hour, the astronomers there were kind and warm.

And, the other grad students are an awesome resource as well! I cannot stress this enough. They can help you with coding/homework problems, give you inside information on people’s advising style, and teach you how to write proposals effectively. Do NOT pass up your peers – they’ll probably know a lot more than you, and will be happy to put off doing their own work to help you out.

Monday, July 25, 2011

Amazing Picture of a Planetary Nebula

While waiting for my code to run at work today, I stumbled across this image of Kn 61 from the Gemini Telescope. This is known as a planetary nebula, where bubbles of gas are thrown out from a dying star. Ultraviolet light from the hot, dense core light up the expelled gas, creating the beautiful object seen below.

I've seen a lot of astronomy-related images, but this one is one of the coolest I've seen in a while. Wow!

Wednesday, July 20, 2011

Globular Clusters: Tracers of Galactic Evolution

Globular clusters are a tight aggregation of hundreds of thousands to millions of stars. They are very old, devoid of gas, and have stellar populations that share the same age and chemical composition. To give you an idea of how old these systems are, it’s known that the Milky Way's globular clusters have ages ranging from 10-15 billion years. This means that these clusters could be relics of the formation of the Milky Way itself!

Empirical observations show that globular cluster luminosities are roughly proportional to the stellar mass of their host galaxy, which suggests that the formation of globular clusters and galaxies are related. However, how they are related is currently not well understood.

In addition, globular cluster populations in the Milky Way exhibit a curious bimodal distribution in their metallicities, where one group belongs to a metal-poor, spherical halo surrounding our galaxy, and another group belongs to a metal-rich, flattened distribution in the bulge and disk portion of the galaxy. Metallicity in astronomy simply refers to how much iron (or metals) is in proportion to hydrogen - the higher the metallicity, the higher the fraction of metals and vice versa. West et al (2004) provided the shown histogram of cluster metallicities for three galaxies. Again, why there are two distinct populations of globular clusters remains in disagreement. What is known is that the vast majority of other galaxies also have metallicty distributions with two or more peaks.

Although globular clusters are interesting in their own right, and can fill many books, I'm particularly interested in what they can tell us about galaxy evolution. There are two competing theories about cluster formation, with different implications about galactic evolution depending on which model is correct:

Model 1: Globular clusters are formed early in their respective galaxies, but are captured or cannibalized from subsequent mergers. If two galaxies collide, it is not unusual for the smaller galaxy to be ripped apart or absorbed by the larger galaxy. In this case, even though the progenitor galaxy would be destroyed, the globular clusters within it would remain intact. There are many such clusters in our galaxy that we think could have been captured this way.The image to the right shows the remains of galaxies absorbed by a giant elliptical galaxy in Abell 3827.

Model 2: The different populations of clusters correspond to distinct periods of star formation. The hydrogen rich, metal-poor clusters formed first, and then, after supernovae enriched the galaxy with metals, the metal-rich population came after. But how is this star formation triggered? It’s expected that star formation occurs steadily throughout a galaxy’s lifetime. However, if that were the case, the globular cluster populations should have metallicities that smear out into many different peaks. The double peaked distribution suggests that specific periods of star formation are needed, with the bulk of cluster formation occurring within relatively short bursts of time. This behavior could be explained by a merger of gas-rich galaxies. Shocks from two colliding galaxies could compress gas enough to form new globular clusters. In some interacting galaxies, massive star clusters that look tantalizingly like young clusters have been observed.The image to the left shows a Hubble image of a pair of colliding galaxies, which seems to have sparked a burst of star formation and over 1,000 massive star clusters (recognized by big blue clumps).

My suspicion is that clusters form in both these ways. The question, then, is which of these processes dominate cluster formation?

If Model 1 is correct, then the large star formation processes that produced globular clusters must have ceased a long time ago. Could this give us information about how galaxies evolved in the young universe? What would give rise to such vigorous star formation in the past, but not today?

If Model 2 is correct, could we then infer the metallities and kinematics of progenitor galaxies? What kinds of progenitor galaxies merged to form the large galaxies we see today? Is it possible large galaxies formed from a couple of gas-rich mergers? In that case, we'd expect to see over densities in globular cluster populations. Or, do large galaxies form from many mergers? If this is the case, the gases in the progenitor galaxies may have been used up in star formation from the multiple merging events, which could effectively deplete the materials needed for cluster formation. Perhaps this could provide another avenue to study the poorly understood physics of galactic mergers in general, such as gas heating and cooling, feedback from star formation, and the complex interplay between them.

I do not have the spectroscopy needed to date globular clusters, or to distinguish between different populations. However, I do have survey data of a large number of galaxies (on the order of thousands) from the Spitzer Space Telescope. I plan on looking at globular cluster populations to see if there are any over densities, and if so, what those over densities are related to. I do have some candidates that look promising, but at this point, it's too early to tell. Automating the detection and data reduction process has been difficult these past few months, but the prize is well worth the effort: a glimpse into galactic history.

Note: All of these images (except the top one of M80, which I jacked off of Wikipedia) come from the work of West, Cote, Marzke, and Jordan. They wrote a wonderful review paper in Nature on this very topic. If you're interested, I suggest you click here:

Wednesday, July 13, 2011

Reasons for This Blog

Yes, there is more to this than seeking attention. There are a number of things I hope to accomplish and share, with the main goal of re-fostering within myself a sense of wonderment in astronomy. Within the space of a year, my outlook on life went from the previous post to one of quiet desperation. I want to change that. No, I need to change that. For some reason, late at night a couple of nights ago, I figured this would be a way of fixing it. So, here are the main reasons for starting this blog:

1. Hold Myself Accountable for My Mistakes:

I failed my first year of grad school. I don’t mean my classes – I did ok in those. No, I failed at the most important part of being a grad student: starting my research. I went from an idealistic, hopeful student to a jaded, emotionally wrecked bum. I spent most of the year feeling depressed and hopeless, and I dealt with it by wallowing in self-pity. However, I didn’t have to! I was somewhat unlucky in how things turned out, but I am far from blameless. I hope that by reflecting on what I could have done better, I can face the rest of my grad school career with a sense of personal responsibility and purpose. I sincerely hope my mistakes won’t become yours.

2. Renew Self-Interest In My Research:

The intense frustration I felt at not making any progress in my research effectively killed any enthusiasm I had in astronomy. That’s bad, because there will always be failure in this field. In fact, there will always be failure in life, but I digress… I hope that I can use this forum to post things in astronomy that interest me, whether it’s related to my research or not. The important thing is, astronomy should have a bigger emphasis in my life, and if I’m not excited about my project, something needs to change.

3. Practice Writing Skills:

As a student in a STEM field, my practice in this is sorely lacking. I recommend finding some way of practicing writing skills, because it’s so important in communicating ideas. I have found that since I don’t write all that often, my writing is awkward, laborious, and time consuming. And I’m not even mentioning my public speaking skills!

4. Foster Public Interest In Astronomy:

This is pretty self-explanatory. As a T.A., I was shocked to discover last semester how little students knew about basic astronomy concepts. I was even more shocked to discover that their apathy toward the subject outweighed that even more. I understand that astronomy is not for everyone, but without public support, astronomy in this country will fail. Just look at the current funding situation.

5. Show That Astronomy Is An Important Aspect Of My Life:

This may be directed more toward me than it is at anybody else. While I have other passions, I need to remind myself that just because astronomy isn’t as well documented photographically, it’s not any less important. ☺

Well, that’s a lot of blogging within the past couple of days. This is really a lot of writing for me in my spare time. Until next time, happy computing!

Tuesday, July 12, 2011

Night Wonders (Or, Why I Love Astronomy)

I remember a drive my parents made once. It was in the dark of night, I was swaddled in a blanket, and the city lights had long since receded into oblivion. We stopped in the middle of a desert landscape, and when I got out, all I felt was the cold seeping into my bones and the desire to fall asleep again. My mother pulled me out of the road and gently told me to look into the night sky, and when I did, what I saw took my breath away. There, in the depths of what I thought was unchangeable and static, was a comet. This strange visitor from the unknown, this smudge of white light from the farthest reaches of space, had saw fit to grace us with its presence. I felt then neither the cold nor the tiredness I had felt earlier, but some strange sort of awakening. I must have been young, because the desert brush towered over me, but at that moment I wondered where it had come from and how it came to be there. I wondered what it meant, and why it was here. And then I looked past it into the stars gleaming coldly behind it and asked my questions again.

Later, there were times when I'd get upset - mainly about my insecurities, my weaknesses, my doubts. As an angsty teenager, I'd run out of the house, defiant of the authority my parents held over me but still unhappy about whatever it was I was running away from at the time. About four houses to the west of mine opened up to the mesa, and it was to there I'd run to for sanctuary. Out in the wilderness, again I'd look up, and again those points of scintillating light would shine down, enough to be seen but hard to understand. I would laugh at my foolish vanity, because in the face of forever, what did it matter? Looking into the universe, albeit a limited window into it, all my worries would seep away and become replaced with the awe of my childhood memory. What is our place in the universe? What is the meaning of it? How did it come into being? Are there other levels of consciousness far exceeding our own? And then an even stranger question: why is there the assumption that the universe holds any meaning? Is meaning, in fact, only a human construction? A human yearning to comfort ourselves that we are in fact important and that sentience is something more than molecules forming protein strands?

Today, I know the universe is not as static or unchanging as I had previously thought. It's a vibrant and violent place involving unimaginable distances and terrifyingly powerful energy. However, I still do not understand any more than I had earlier, because each new revelation brings with it new questions to outnumber the old. And my quest for meaning, or perhaps lack of it, is still as strong as it ever was. Maybe my reasons for going into astrophysics are cliche - the overall "meaning" of the universe, aliens, strange planets and their stranger horizons - but it's those basic questions that keep me going. It's still what I ask when I gaze up into the night sky, my head full of wonder. In fact, I feel like a child.

Monday, July 11, 2011

Hello, World!

In honor of my first post (and because I could think of nothing else), I will start my blog the traditional programmer's way - python style! So . . .

print "Hello, World!"

Simple as that! And if that 's not enough, here's a way you can say it in 366 other computer languages:
Click here!!