Kindle the flame

I often hear that what causes people most awe when they look to the night sky is the Moon. Other people revere the Sun, and some are oddly attached to the movement of planets on the sky and how they affect our destiny (hint: they don’t). To me, well, the Sun has its appeal. But what really fascinate me the most is the stars. And I believe this is something that started when I was just a little kid reading about astronomy in a very graphic atlas. I remember reading that our Sun and the planets of the Solar System had layers, just like an onion, and that these layers were made of materials under extreme conditions of pressure and temperature. But sometimes I wondered: how do we know these things?

Now, because of an unfortunate turn of events that lasted between my teenage years, I almost completely lost the interest in astronomy, until one day I was sitting next to a bus window and looked at the night sky while traversing a rural area (where there’s no light pollution). I remembered how beautiful and mesmerizing the sky could be, and my passion for the stars was re-kindled. I still did not know much more about them, besides being rusty because of spending so many years misusing my brain. I still did not know much about the stars, the reason why I started reading things on the internet and listening to my all-time favorite podcast Astronomy Cast. I believe most of what I know now about astronomy was learned in one of those DIY sessions of curious learning (and that’s why I tend to oppose traditional “classroom learning”; more on that here and here).

Later, I learned that stars have layers of materials because they work like huge factories of heavy atoms: they produce these atoms at the nucleus, which gets carried outwards, and start forming layers. This superficial material will then be expelled to space in a number of ways (e.g. supernovae or stellar winds). Sometimes, a very massive star creates atoms like silicon and iron, which will form planets and rocky bodies on the next generation of stars. The density of the heavier atoms cause them to accumulate faster than the lighter atoms (hydrogen, helium), and that’s why the cores of the planets are so dense and rich in metals. However, to this date, we still don’t know exactly how the formation of a planetary system happens in detail. And that’s why there are so many scientists looking for extrasolar planets (exoplanets): they’re not only searching for extraterrestrial life, but creating this massive database of information on planets that will help us understand how they are formed.

When I got my first telescope (which was given by my uncle as a posthumous gift from my father – who always endorsed my decision of pursuing my dreams), during a very cloudy and hot summer, the first object I observed with it when the clouds gave away a little bit was Sirius, the brightest star seen from Earth. While we can’t see the details of the surface of a star because it’s too far away, it was absolutely mesmerizing to realize that an object so distant can output so much energy, and how crazy it was to have an artificial eye with the size of my hand. A few weeks later, I would be tearing the telescope apart and re-building almost from scratch just to see how it worked and get a more accurate alignment of the mirrors. From that endeavor, I wrote this article on wikiHow, and I am very proud and thankful for all the contributions.

I remember that when I started studying astronomy in college, I wanted to research stellar evolution. So I got a project that aimed to investigate the life of a star, more specifically the one that produced the planetary nebula NGC 40. Although they have this name, planetary nebulae (PN) don’t have anything to do with planets [1], they are the outer layers of a star (similar to the Sun in mass) that were blown out of it because the gravity could not sustain them anymore. What remains at the middle of the nebula is the core of what was previously a star, and this core still emits energy, which illuminates the PN. The objective of this research is to identify the main features of this star (mainly its initial mass and composition). The problem with this particular object is that the core of the PN is weird: it has very little hydrogen, and some physical parameters like temperature and luminosity are not completely understood. All these things make the object particularly interesting. A followup to this research is to extend the study to other planetary nebulae and to understand how their stars evolved.

If you think I am not obsessed enough with stars, during my exchange period studying in Netherlands, I decided to branch from the death of not-very-massive-stars to the birth of very massive stars. And again, I studied a particular object, this time the massive protostar AFGL 2591 (information on Wikipedia is very outdated). In fact, the mass of this object is estimated to be 40 times higher than the Sun’s. If you want to feel some sense of scale, Sirius is only 2 times more massive than the Sun. You can imagine that AFGL 2591 is going to give birth to a hell of a monster star [2]. I have a special page dedicated to this project here (it can get somewhat technical though).

On that note, this week, I received some great news: I was accepted to conduct my Master’s degree at the University of São Paulo, starting in March/2015. And I am very happy to announce that I will further study stars, and I will probably take a more observational route, which is something that I’ve been looking for for years now. The details of the project are not decided yet, but things are going forward.

Ah, the stars. So far away, and yet, so influential in my life. Except for the fact that one of them may one day explode and wipe out the life from Earth, stars are absolutely gorgeous. They make the stuff that makes us. They produce the energy necessary for life to flourish. And they are our way of understanding the universe. You can’t escape the influence of stars in astronomy, even if you go extragalactic, for it is the light of stars that trace the galaxies [3]. What’s not to love about them?

 

[1] Well, at least not directly, because the presence of a massive planet near the star can, supposedly, alter significantly the chemical composition of the environment inside a PN.

[2] Or more than one monster star. It’s difficult to resolve the individual components inside the object with our current instrumentation. In my research, there was no clear indication of multiple cores inside AFGL 2591.

[3] Some galaxies, however, have another output of luminosity: supermassive blackholes (more specifically, the material around the black hole). These galaxies are said to have an active nucleus.

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Kindle the flame

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