Calculation Of A Big Boom

Credit: NASA/CXC/JPL

Infrared image of Tycho's Nova which is the remnant of Type Ia supernova.

Because of the work of our guest last Wednesday, Dr. Ryan Foley, and some events earlier this year, I feel that it is time to study something about the supernova.

When a high-mass star reaches the end point of its life, it explodes into a big ball of flame called supernova.  Astronomers have calculated that around 3 massive stars will go through a special Type Ia supernova every thousand year in our Milky Way galaxy. In other words, within distance of several thousand light year from Earth, a fair amount (20+) of stars is about to give a big boom. The picture above shows a nice picture of the remnant of supernova. It is beautiful to observe from some distance but we don't want to get too close to the explosion. That is why we are trying to determine when a star will blow up.

Did Baptistina Asteroid Cause Dinosaur's Extinction?

Credit: www.tickreel.com

There are many theories behind the extinction of dinosaurs 65 million years ago. One theory is that an impact of an asteroid causes it but no one is sure what type or how the asteroid heads to the Earth. From the study in 2007 by using data from observatories in visible-wavelength range, the culprit is the type of asteroid called "Baptistina."

Stellar Properties From Afar

by Mee Wong-u-railertkun, Nathan Baskin, John Pharo, David Vartanyan

Credit: apod.nasa.gov Info about this picture is presented below.

We present the solution to the first question from the worksheet "Stellar Properties From Afar."

We are given the following information about the sun,
1) The angular diameter of the sun is 0.5 degrees.
2) The astronomical unit (AU), distance between the Earth and the Sun, is approximately 1.5 * 10^13 cm.

Determining the Astronomical Unit from Mercury's Transit

by Mee Wong-u-railertkun, John Pharo, David Vartanyan

We were given a picture of Mercury's transit taken by NASA's Transition Region and Coronal Explorer (TRACE) which is a polar low-Earth orbit satellite. The picture looks like this.

Planet Surface Temperature

by Mee Wong-u-railertkun, John Pharo, David Vartanyan

Abstract

We investigate the relationship between the energy emitted from a star and the surface temperature of a planet. We assume that a star and a planet are perfect spheres and they are perfect blackbodies, i.e. power absorbed equals to power emitted. Moreover, they radiate isotropically. Later, we compare between the theoretical surface temperature of the Earth with the real data.

A Brief History of Palomar Observatory

Credit: www.astro.caltech.edu/palomar

Since we, Ay20-ites, are going to Palomar Observatory tomorrow (Sunday 10/16), I should dig out some information before hand. Inside the big dome, the temperature is kept around 30 to 40 degree so we better bring a jacket!

The Palomar Observatory is located in north San Diego County, California around 100 miles south of Caltech. Its coordinates are 33 degree 21' 21''N and 116 degree 51' 50'' W with the altitude of 5618 feet or 1712 meter. It is a world-class instrument for astronomical research that is owned and operated by the California Institute of Technology. The observatory is consisted of five telescopes including the 200-inch telescope.

Recalling Blackbody Radiation

by Mee Wong-u-railertkun, John Pharo, David Vartanyan

Abstract

We present the solution to the Black Body Radiation worksheet problem 1, from week 3, recalling basic ideas of black body radiation from energy density to specific intensity and flux. In the first part, we investigate the contradiction of the units of energy density. In order to convert from energy density to intensity and flux, we have to study the concept of solid angle. These equations are used frequently in astronomy.

On The Way Back

After finishing Ay20 helping session, Iryna, Nathan, David, and I walked back together while talking about the "Phinney-unit." Then, Iryna pointed at a bright spot in the sky near to the Moon and asked, "Is that a planet?" Nathan replied, "Yeah, that's Jupiter. Actually, if you look through a binocular, you can see the Galilean moons." So, after grabbing a binoculars at Nathan's room, we looked up in the sky and saw the following picture.

Basically, we saw the jupiter with two moons to the right. That makes me wonder, which two moons are we looking at? So, when I came back to my room, I opened up the program called Stellarium and checked it out.

Those two moons turn out to be Ganymede and Calisto. We can't see Io and Europa, may be because they are close to Jupiter today (or I just have bad eyes.)

Observation Planning For The Very Large Telescope and The Keck Telescope

by Mee Wong-u-railertkun, John Pharo, Eric Mukherjee, Nathan Baskin

Abstract

We present the solution to the Celestial Sphere and Observation Planning worksheet problem 4, from week 2, picking range of declination that both the Very Large Telescope (VLT) and The Keck Telescope can observe galaxies at visible wavelengths for at least 6 months a year. In order to choose a small area of the sky to be observed very deeply, it should be seen by as many telescopes as possible. We use the fact that stars, from Earth’s point of view, circle around the North Celestial Pole (NCP) and the South Celestial Pole (SCP) to determine behavior of stars at different declinations seen from VLT and Keck.

Estimating The Radius of The Earth

by Mee Wong-u-railertkun

Abstract

We present how the radius of the Earth could be measured using only a stopwatch and a place where the horizon can be seen, e.g. beach. A stopwatch and a difference in height provide the curvature of the Earth by watching a sunset and assuming that the Earth is a perfect sphere. Since a person’s height is much less than the radius of the Earth, one small error in a measurement could mean a large inaccuracy in the final answer.

"Wet" Mars

Credit: www.esa.int

           

            On June 2^nd, 2003, European Space Agency (ESA) launched a probe named Mars Express to investigate, well, Mars. Now, it is orbiting its target at the orbital inclination of 86.3 degree with a period of 6 h 43m. On board, SPICAM spectrometer works by receiving a light from Mars, putting it through grating, and looking for a pattern in a spectrum to determine what does Mars’ atmosphere consist of. From a discovery published in Science by Maltagliati et al (2011), Mars’ atmosphere is supersaturated with water vapor.

Looking Outside My Window

           Because of more free time on weekend, I, just recovered from jetlag, finally have a chance to look outside from my room’s window at night. With daylight, the view from my room is a typical parking lot with some trees having picturesque mountain range as a faraway background.

            But tonight is different. As I stared outside my window while working on math problem set, I can see only darkness with some streetlights. Since I turn on the light in my room, the sky outside is completely dark – not a single star shows up. Then, I notice a tiny orange spot. It’s definitely not an airplane or Jupiter since it stays stationary. What else could it be? (I’m pretty sure that it’s not an UFO also) So, I take another picture from my digital camera and compare with the one taken during a day. It’s the area indicated by a red circle. (The camera makes everything look so much brighter than what is seen by naked eyes) Suddenly, I realize that the light must come from one of the most famous places in astronomy history – the Mount Wilson Observatory.

             The Mount Wilson Observatory (MWO) is located on the peak of, well, Mount Wilson at 5715 foot above sea level. It contains two important telescopes: the 60-inch Hale telescope and the 100-inch Hooker telescope.

            The Hale telescope was once the largest operational telescope in the world allowing many scientific procedures, e.g. parallax measurements, nebula photography. The Hooker telescope, also, was once the largest telescope until the 200-inch telescope at Palomar Observatory was built (which is also called Hale telescope.) Here, Edwin Hubble, a prominent astronomer, made the discovery of redshift which leads to the conclusion that the universe is expanding.

            It’s true that the MWO appears as a tiny dot outside my window. However, its place in the astronomy history gives me some inspiration (at least enough for me to write this post!) To be true, the scene of parking lot with an orange flickering spot is not bad at all.

T.K.O. Mathematics

          There are plenty types of martial art – boxing, taekwondo, sumo, judo, aikido, kung fu and solving math problems. Hold on a second, mathematics? Even though they might come from different fields, math and martial arts are more similar than differing. Picking up a fight is a good analogy to solving problems. (Proof? We, at least once, were “knocked out” by a math problem on an exam. Don’t tell me that you never had that experience!)

            In boxing, both amateur and professional, there are plenty of rules and settings – size of the ring, referee, using only fists, time per round etc. If a boxer violates a rule, he/she might get a point stripped off or even disqualified. In order to box, a boxer needs to have appropriate equipment. A paradigm of problem solving nowadays is similar to a rigorous boxing fight. Every step has to be beautiful, strict and perfect. Addition or multiplication must be exact, no room for estimation.

            However, not every fight in this world is staged in an arena. Actually, there are more “street fighting” than official boxing match. In street fighting, no rule applies – dirty tricks are even acceptable. It doesn’t matter how the strikes were conducted. Final result is the most important goal – not the beauty of a kick or the style of fighting.

            Sanjoy Mahajan, a professor at Massachusetts Institute of Technology, broke a paradigm of problem solving by introducing the “street fighting mathematics.” In some situations, the top priority is the final answer, not the pathway. Frequently, life attacks you with rough questions. Most of the time, an exact answer is not required to survive; a rough answer will do the trick. Thus, if you confront with problems in unofficial situation, you are free to make some rough assumptions and estimations. The answer might not be 100% correct but, with reasonable assumptions, it should turn out to be in the same order of magnitude. For example, a student solves a problem and discovers the Earth’s radius to be 2000 km. Even though the right answer ranges from 6353 km to 6384 km, the student’s answer is good enough for street-fighting mathematics.

            For practicing, there are couples of question for street-fighting mathematics in Ay20 first set. (The link is http://www.astro.caltech.edu/~jrv/Ay20/ws/ws_collab_sfmath.pdf) But don’t forget, even though it is a convenient way to solve a complicated problem, street-fighting mathematics is casual. In official exams, e.g. Caltech finals, it is fine to use street-fighting trick to figure out a problem roughly but not entirely. Otherwise, you would get a T.K.O. from a professor, if not an F.