This is an RGB image using the infrared bands of Wise 1, 2, and 3. These three images are of the same size, so it works on the astropy package I am using without having to install Montage. I made 3 red, 2 green, and 1 blue. As you can see from all that red smudge, WISE 3 is sort of hazier. You can’t actually see a brown dwarf very well from WISE 3 band, so I guess this helps.
Before I begin, there is a previous post that I would like to comment on my previous post. Apparently what I did was not combine three images and create an RGB image based on them. What happened instead was I put WISE 1, J, and K on top of each other, so all you could see was WISE 1 on top. Bummer. In order to do that, I have to install Montage, otherwise the images won’t rescale and stuff to fit each other. Unfortunately, it looks like a Linux kind of thing. Oh well.
Moving on to greener pastures, I have been changing a value called vmin and vmax. It allows me to set up a scale of color or black to white that depends on how bright the pixel is. So, let’s use the grayscale here for simplicity. If the pixel is as bright as the vmax value, then that pixel is white. If it is as dim as the vmin value, that pixel is black. In between it is all shades of gray. So, what happens, say if you bring the value of vmax down? The dimmer objects become whiter because now the brightness is closer to the vmax boundary. See here:
As you can see above, the bright object is still white when you lower the vmax boundary, but the whiteness becomes wider, while the dimmer object becomes whiter because it is closer to the line. That way, you can make dim objects stand out. See here two pictures below, one before the change, and one after:
As you can see, it is much clearer that there is actually a thing shining right in the middle of the circle. I made the brown dwarf stand out.
This is what it has come to. A bunch of science museums afraid of teaching facts about climate change because of moneyed interests not wanting their playtime to end. And the chickens running those places won’t even take a stand. Disgraceful.
I made a colored picture using J band of 2MASS (1.25 micrometer), K band of 2MASS (2.17 micrometer), and Wise 1 (3.4 micrometer). Basically, each band represents the different wavelengths in which the telescopes captured the images. So, I put them together using python and got:
Neat! I believe the faint dot in the middle is the brown dwarf here. Hopefully I got did it right.
I Hope That Whoever Wrote the Programming Documentations Suffered Grievous Harm From Stepping on LegosJune 12, 2014
I spent hours upon hours trying to install APLpy with pip, trying whichever way to make it work. All because someone couldn’t give a damn about the details so it can be accessed by newcomers. So I am going to do everyone a favor and tell you all how to do this for Windows.
Installing pip itself is easy. Just follow the link, download it, and then double click on the python program. This will install pip by itself. It is the using part that made me want to rip my hair out. And according to a friend, it is kind of Windows fault for sucking so much. Anyways, firstly, turns out, don’t use the python shell. Use the command prompt. Yeah, they don’t tell you that, assuming your average newcomer is a giant computer nerd. Well, not everyone is a computer nerd, they can be a physics nerd like me, OKAY!
Next up, go to the PC icon, right click, properties, advanced system setting button, and go to the advanced tab. There is an option called “change environmental variable”. Click on PATH and edit it so it goes to C:\Python27(mine was python 2.7, yours might be different)\Scripts. NOW you can go to the command prompt and type: pip install name-of-package-from-PyPI-you-want-to-install.
I don’t know why that is and why this ridiculous roundabout way has to exist, but those goddamn writers didn’t even bother to make it easy for new users. They just tell you, “go do this” and expects you to automatically get what to do despite it not being obvious for noobs like me. Someone please hold a writing workshop or something for these people because I have just had it trying to install all these dependencies and making things work.
So, there have been two exciting planetary discoveries last week:
a) Two planets have been discovered around Kapteyn star, which is around 13 light years away. Since planets form with the star at around the same time, and the star is around 11.5 billion years old, the planets are the oldest known. Kapteyn star itself is likely to be a star of another tiny galaxy absorbed into the Milky Way, the remnant of that galaxy being the globular cluster Omega Centauri. Both planets are super Earth, with Kapteyn b having the possibility of liquid water to exist. Link here and here.
b) The most massive terrestrial planet yet has been discovered, and it is dubbed a mega Earth. Kepler 10c is 17 times the mass of the Earth, which is basically around Neptune’s mass. The size, though, is 2.3 times the Earth. This means the object has the density of a rock, so we know it can’t be a gas giant planet like Neptune. It is indeed a new type of planet, since a rocky planet is not expected to be this massive. I love surprises like this! More here and here.
I don’t have anything particular to say about them. They are pretty much a technical summary of brown dwarfs found, classification of spectra, proper motion (angle speed in sky), and distance, which were found using the 2MASS survey and WISE telescope. You can read them here, here, and here, if you want to learn more about brown dwarfs. They are pretty technical, though.
Update: You know what? I was mulling things over, and turns out there are a few things I want to comment about. Firstly, there is a spectral classification cooler than the T type, called the Y type, which is characterized by absorption from ammonia. These brown dwarfs are cooler than 600 K. The articles above talk about some of those.
Secondly, the articles above have a large focus on high proper motion brown dwarfs. Higher proper motion implies that the object are more probable to be closer to us than those having low proper motion. Think about it this way, when you are in a car, things that are far away look slower than things that are closer to you. It’s not so much that in reality things that are farther away are slower, as it is the fact that things that are farther away has lesser angular movement because distances look smaller when farther away.
How are proper motion found? Well, turns out that the 2MASS survey took observations a decade previous to WISE telescope. So, you look at the pictures from 2MASS, and you look at one from WISE, and see how much the position has changed in angle. The objects are likely to have constant speed, so just divide the angle difference by the year difference.
What is proper motion helpful for? Well, it let us know that an object is likely to be close to the solar system. This is supposed to help bridge the gap in our knowledge of the solar system neighborhood. The distance itself can later be taken using parallax. Aside from that, finding close brown dwarfs is also helpful because it will help us study the atmosphere better. We still have an imperfect model on the process behind condensation and cloud formation in the brown dwarf atmosphere, and the more of them we find, the better we will know the details behind it.
This is what an image for brown dwarf looks like, just a faint dot. As you can see in the link, each of those four images represent the different wavelength of infrared the pictures were taken. Obviously WISE band 1 and 2 (WISE is the name of the telescope) are best for this sort of stuff. Oh, and fun fact, this one was discovered by my prof.
I talked with my prof and got further information on what the point of the project is. It has to do with the Kepler space telescope. If you haven’t heard, two of its four wheels, which are used to point the telescope to a location, are broken, and so the telescope can’t maintain its sight to a position in the sky. Not only is there the fact that it is rotating around the Earth, the light from the sun has momentum. The light will push the telescope, and the irregularity of the telescope’s shape causes it to torque. The only way for the telescope to not be perturbed is to lie perpendicular to the sun. Unfortunately, that means that it can only observe in the plane of ecliptic, and it can’t maintain the same field of view throughout the year as the telescope has to maintain perpendicularity to the sun as the Earth orbits the sun. Nevertheless, useful science can be done. The telescope will observe certain fields of view, and when time is up, it will rotate again to another field of view that will maintain perpendicularity.
The point where my research comes in has to do with the way the above procedure means that the antenna is not facing the Earth properly. That means in order for them to continually observe an area in space, they will have to keep the information in the hard drive, and then send it back to Earth once the observation period is over. That means they have a limited amount of data they can store, and so the mission will have to be picky in which data they store. Looking for brown dwarfs to observe is supposed to help out Kepler in keeping . There are areas where not much brown dwarfs discovered, so what I am doing is helping that process out.
For now, I am just installing the astropy library for Python language. l will be looking at some picture of brown dwarfs, download them, and hopefully astropy can take those pictures and present them to me.
So, I got accepted into a summer research program. They are going to pay me and everything, yay! Which is why I thought I should blog about my research.
What I am doing this summer is basically sift through infrared data and looking for object called brown dwarfs and classifying them. Brown dwarfs are in a way objects that represent the transitions between planets and stars. They are much more massive than planets, enough to have fused deuterium (hydrogen, but with a neutron) for a short while, but they are not massive enough to fuse regular hydrogen. The mass may range from 13 to 80 Jupiters. After the short lived deuterium fusion phase, they just start cooling down. They tend to emit most of the light in the near infrared zone. Size wise, they are not too different from Jupiter because the interior pressure is governed by electron degeneracy. Basically, the pressure of electrons due to them not being able to occupy the same energy states is what holds the object from further collapse. In a pressure dominated by degenerate matter, adding more mass doesn’t cause an object to grow much.
How does one empirically distinguish a brown dwarf from a low mass star? There is a simple test called the Lithium test. If one can detect lithium, it is probably a brown dwarf. Stars are hot enough to be able to fuse lithium, unlike brown dwarfs, and lithium fuses at a similar temperature to hydrogen. That said, the highest mass brown dwarfs can burn lithium, so at the high end range of brown dwarf mass, they are indistinguishable from stars. Well, there is another way, but it is harder to do. Basically, measure the temperature and mass of a brown dwarf binary. The theory is that an object of certain mass will have a different temperature curve as it ages than one of a different mass. If an object is massive enough to be a star, the temperature will stabilize due to sustained fusion, if not it keeps cooling down.
Before we go on, I would like to address how we can know what compounds such a distant object have. We look at the spectrum of light from the object, and see which wavelengths are missing. Certain compounds absorbs light at certain specific frequencies because of the way the electrons are configurated energy wise. Electrons can only occupy certain energies, and so they will absorb only light of certain energies. So, when you look at the spectrum of light coming off the planet, there will be chunks of light that will be missing corresponding to the energy absorbed. Imagine that the rainbow has various thin strips on it missing, that is what it is like.
Brown dwarfs come in two spectral type, the L type and the T type, with L being the hotter, more luminous type. The temperature itself is correlated with luminosity by the fourth power, so measuring luminosity gives you the temperature. The spectral types are related to what compounds one detects in the atmosphere. The L types have the temperature range of 1300 K to 2500 K. The hottest L type show vanadium oxide and titanium oxide absorption signatures in the spectra, and as the brown dwarf gets cooler, this transitions to a spectra with absorption due to metal hydride (FeH, MgH, CaH, etc) and Alkali metal compounds (NaI, KI, etc), while the metal oxide absorption disappears. The T type are objects below 1500 K, and the spectra contains absorptions from methane, water, ammonia, and CO. Does this mean that the transition of spectra represents another good way to gauge the temperature of the object? Yes for early L and late T. Not so much for the transition between late L to early T. In that section, the temperature doesn’t change very much while the spectra changes. A point of note is that the temperature/spectra correlation works much better with optical than infrared.
There is a reasonable explanation for the transitions of spectra a brown dwarf undergoes. As the brown dwarf cools, the metal oxides condense and fall off deeper into the atmosphere. This uncovers the spectra from the alkali metals and hydride metals. As the temperature goes lower to the T type level, clouds become an important component. This explains the rapid change in spectra with the slower change in temperature as this transition of dusty atmosphere occurs around a short range around 1400 K. At temperatures lower than 1400 K, the dust sinks and the metal hydrides condense while conditions are right for the reaction of CO+H2=H2O+CH4 occurs, meaning carbon monoxide with hydrogen reacts to for water and methane. This explains the methane absorption that dominates in the T brown dwarfs.
Finally, I would like to point out the model pointed out above for the brown dwarfs differs with metallicity. Metals in astronomy are all elements with higher atomic number than helium. Brown dwarfs are allowed to be more massive and hotter with less metal.
This is a basic summary of what we know about brown dwarfs. If you want to know more about them, you can of course go ahead and read what I linked below. There has also been some advances, like the discovery of below freezing brown dwarfs. And there are mysteries to be solved, like the fact that there are three scenarios for condensations and dusts that plays a key role in the late L to early T spectrum.
I have done all this preliminary reading. Hopefully I know what I will be doing. Granted, there will be some fumbling around as this is my first legit science project ever.
Source and reading materials