May 8: “Al Otro Lado del Espectro” (At the Other Side of the Spectrum)

Our last public outreach night of the semester took place on May 8th and it was a very special one since it marked the first Spanish-speaking outreach event in many years. The whole event was conducted in Spanish, including announcements, the presentation, and the activities that took place afterward. It was a mixed audience, consisting of regular attendees, people interested in practicing their Spanish, and Spanish-speakers in the community.  

Alejandro Núñez, a graduate student in the Astronomy Department at Columbia University, gave a talk titled "Al Otro Lado del Espectro" ("At the Other Side of the Spectrum"). Alejandro started the talk by describing the wave nature of light, and introduced concepts such as frequency and wavelength. Then he showed several spectacular images of celestial objects at different wavelengths, starting from the long-wavelength radio waves, all the way to the short-wavelength gamma rays. He included many images of the Sun, other planets, and our Milky Way.  He concluded by showing us the different telescopes capable of observing the different parts of the electromagnetic spectrum.

After the talk, many audience members went to the roof to see Jupiter and M3 through the telescopes, where they had the opportunity to talk with the Spanish-speaking volunteers.  Some  attendees stayed in the lecture hall asking Alejandro a few more questions. In addition, undergraduate student Gladys Velez-Caidedo  showed several movies on the 3D wall.  It was a good turnout and we expect to have similar events in the future.  

-- Ximena Fernandez (graduate student)

Apr 24: Galactic Synthesizers

Tonight Adrian Price-Whelan, Columbia graduate student and National Science Foundation fellow, showed us how he has used simulated galaxies to compose original music. First, he had to describe the basic shapes of galaxies an how stars move inside them since the motions of stars are the basis of his method. Starting with spiral galaxies, we heard about their three main components: a flattened disk of stars moving in orderly, almost circular orbits around the galactic center, a spheroidal bulge at the center of the disk where stars move in every direction with nearly random orientation, and an outer halo which surrounds the disk and spheroid, spanning an enormous volume but containing only 1% of the stars. The shapes of these spiral galaxies were contrasted with that of ellipticals, which are generally more "bloby" and whose stars move mostly with random orientations which are quite unlike the most prominent largest components of spiral galaxies, the disks themselves. Despite their relative featurelessness, ellipticals are typically triaxial - that is, they have different extents in different directions, which leads to a variety of orbits with different shapes including long-axis tubes, short-axis tubes, and box orbits. 

To turn galaxies into synthesizers, Adrian built a computer model of a galaxy of each type and populated them with stars. Each star moves with specific frequencies, both in and out from the center of the galaxy and around it; these frequencies were mapped onto scales, with low notes corresponding to short-axis tube orbits of the elliptical galaxies and halo stars of spiral galaxy, mid-tones made by the disk and long-axis tube stars, and high notes produced by box orbits and stars in the spheroid. As the simulation advances the stars ring their notes in a manner similar to plucking a guitar string, while encoding actual physical information about the shape of the galaxy they orbit in to sound. You can listen to his compositions over on Soundcloud: spiral galaxies, elliptical galaxies.

Following Adrian's talk, Columbia graduate student Emily Sandford presented some slides describing variety of Earth-Sun-Moon arrangements and how they lead to solar and lunar eclipses, which then smoothly transitioned into a discussion of the Kepler space telescope since it uses a very similar principle to find planets around other stars - it precisely measures the dimming caused by an extra-solar planet passing between its host star and the Earth. Upstairs, undergraduate Gladys Velez-Caidedo and post-doctorate researcher Shy Genel ran the 3D wall, illustrating a wide variety of astronomical phenomena.

-- David Hendel (graduate student)

Feb 27: Neutron Stars

This past Friday, Slovko Bogdanov, a research scientist at Columbia University, gave a great talk telling us all about neutron stars. While stars are kept from gravitational collapse by the burning of their nuclear fuel, when this fuel source runs dry, look out! The resulting supernova can outshine the light from an entire galaxy. Neutron stars are the result of this process -- when a massive star collapses, the remainder is so compact that it can fit the mass of the Sun into a star the size of Manhattan. We looked at a number of supernova remnants and learned out about the discovery of fast spinning pulsars. We also learned about an event in December 2004 where a starquake in a magnetar (a highly magnetized neutron star with magnetic fields more than 100,000,000 times stronger than anything scientists can create) released a blast of gamma-radiation so strong that it had the same ionizing effect on our atmosphere that strong solar flares do -- but from a distance of 50,000 light years. Yikes!

Afterwards, Columbia Post-Bac David Jaimes gave a slideshow on the recent Rosetta Mission, where after 10 years, we successfully landed a probe on Comet 67P. He showed us some gorgeous close up images of the comet, and described some of the science behind this amazing feat of engineering. Others wandered to our 3D-wall, where we screened several different movies showing simulations of colliding galaxies and more. Up on the roof, the skies were clear and we had clear views of Jupiter, the moon, and the Orion Nebula with our Big and Little Dome telescopes.

-- Jennifer Weston (graduate student)

Feb 13: New Developments in Gravity

It was a pleasure to have Dr. Rachel Rosen, Assistant Professor of Theoretical Physics at Columbia University, give a lecture on the New Developments in Gravity. Dr. Rosen is an expert in areas of research pertaining to field theory, cosmology, and particle physics. She is recognized for her contributions to the theory of massive gravity, a modified theory of gravity. In the lecture, she explained to us that the currently accepted standard theory of gravity is Albert Einstein’s general relativity. In this theory, the graviton (the particle responsible for the force of gravity) is a massless particle. However, Dr. Rosen stated that people have been interested in whether or not it's possible to modify this theory of gravity, particularly at large distances. One way to do this is to give the graviton a mass and make it a massive particle. Recently, it has been shown that it is possible to have theoretically consistent theories in which the graviton has a mass. The recent discovery of dark energy and the associated cosmological constant problem has prompted investigations for long distance modifications of general relativity. Dr. Rosen believes that making the graviton a massive particle may lead us to understand natural phenomena like the observed expansion of the universe.

After the main lecture, graduate student, Stephanie Douglas, gave a brief talk on star-forming regions in open clusters.  She showed images of open clusters such as Trumpler 16, Pleiades, Hyades, Alpha Persei, all ranging in age between 500,000 and 680 million years. Stephanie explained how some of the open clusters have regions that glow differently in different parts of the light spectrum (i.e., visible versus infrared).  She explained that when look at regions obscured by gas and dust in at different wavelengths we can pick out areas where stars are being formed.

After the lecture, audience members headed up to the roof to see the Moon, Jupiter, and the Orion Nebula. Graduate student, Adrian Price-Whelan, set up a digital SLR camera in the Big Dome to demonstrate how it's still possible to see faint sky objects, even from the heart of New York City. The image below was taken through our 14" Meade telescope.

-- David Jaimes (post-back student)

Jan 30: Cosmic Stretchmarks

Tonight Princeton post-doc, and cosmologist, Renee Hlozek explained what light can tell us about the early universe. She showed us this map of light from the early universe, called the Cosmic Microwave Background, which is almost entirely uniform - the temperature fluctuations shown are only a few parts per million. But such uniformity, along with the observation that the universe appears perfectly flat, was a problem for theories about the universe's beginning.  For the temperature fluctuations to be so small, every part of the universe must have been in contact at the beginning. Renee used the example of communication across the big lecture hall - if she asks the person in the front row what the favorite band is of the person in the back corner, the front row person won't know unless she has talked to the other person. 

So scientists came up with the theory of cosmic inflation, which explains the Cosmic Microwave Background very well. But Renee also told us that scientists don't want their theories to simply explain existing data - good theories also make testable predictions for future observations.  And inflation theories predict that we should see a particular type of polarization (the orientation of light rays as they reach our detectors) that isn't produced by any other object in the universe. So if we detect that type of polarization, called B-modes, then we have good evidence for inflation!

Many experiments are studying the Cosmic Microwave Background, and last year one of them announced that they had detected B-modes, but a leaked press release for tomorrow indicates that their supposed detection was probably due to interference from dust in our Galaxy. Renee told us that this is a product of good science - the scientific method involves checking your own and other people's work, to make sure results are accurate.  Renee works on a collaboration using the Atacama Cosmology Telescope, one of many experiments studying the Cosmic Microwave Background. She showed us a picture of the telescope, and also of four women who built one of its instruments. Another instrument currently being added to ACT will also look for B-mode polarization - it may still be out there!

After the main lecture, graduate student Andrea gave a short slideshow on a few asteroids and comets that have passed by Earth recently, and undergraduate Erin showed movies on the 3D Wall.  Graduate students Adrian, Jose, and Emily, along with undergraduate Rasmi, braved an extreme wind chill to let our attendees see Jupiter and the Moon from two dome telescopes on the roof. 

-- Steph Douglas (graduate student)

Nov 21: Constellations R Us

This week, Irene Pease guided the audience through the constellations on the sky. Irene Pease has works as an astrophysics educator and leads astronomy classes as a Brooklyn’s Friendly Neighborhood Astronomer. During the lecture, Irene Pease showed us the distributions of constellations on the dark night sky in well-populated cities (e.g., New York) where city light has been a plague. Ancient sky across different cultures, such as Egyptian, European and Chinese, were compared, which amazingly showed great similarities in the definitions of constellations. She then introduced the modern constellations which were defined by Interactional Astronomical Union (IAU). The celestial sphere are divided into 88 official constellations, most of which inherit their names from their Graeco-Roman predecessors (e.g., Orion, Leo), while those in Southern sky have more modernized names (e.g., Microscopium). By using a ball and a cartoon paper to mimic the earth and horizon, Irene also explained the rotation of the celestial sky relative to the earth and the different paths of stars across the sky as viewed by observers at different latitudes. 

After the lecture, a video “The First Earth-sized World of Alpha Centrauri” was shown to the audience. This 7-minute long video introduced the first earth-sized planet orbiting around the star Alpha Centauri. On the roof, observations of double-star Alberio, open cluster Pleiades were led by graduate student, Jose Zorrilla. 

-- Yong Zheng (graduate student)

Nov 7: Juggling with Black Holes

This week, Hubble Postdoctoral Fellow Andreas Kupper described the dynamics of multiple massive objects in the same system.  When two massive objects are near each other, they exert gravitational forces on each other and their motions can be described analytically - that is, the motions at all times can be calculated by hand from basic theories.  When three or more massive objects interact gravitationally, the interactions become complicated and can only be modeled using computer simulations. Andreas showed the results of a few of his simulations - after the objects orbit chaotically around each other for a while, one object (usually the one with the lowest mass) is thrown out of the system with a very high velocity.  The remaining objects end up closer together, and this process, called scattering, is thought to be responsible for bringing massive objects like black holes and neutron stars close enough together that they can merge into an even more massive object. 

After the lecture, audiences were treated to a showing of LIGO: A Passion for Understanding, a 20 minute film about a project to detect gravitational waves coming from closely interacting massive objects.  After the film, graduate student Aleksey Generozov and I answered questions about gravitational waves and LIGO.   Graduate student Yong Zheng was the roof captain, sharing glimpses of the Moon, Albireo and the Ring Nebula while undergraduate Pratishta Yerakala took attendees on a 3D tour of the Universe with the 3D wall.

-- Steph Douglas (graduate student)