The Lithium Problem

We are familiar with the solar lithium problem. Lithium is of low abundance in the universe, and like the abundance of any element, this is a result of stellar nucleosynthesis. It is of even lower abundance in our sun, and this problem remains unsolved.  We are beginning to discover other places where anomalous concentrations of Lithium exist, and these stellar, interstellar, and exoplanetary lithium problems may fundamentally change the way we see star formation.

Active region toward the limb of the Sun, with spicules (right) and some sunspots (upper left). Image captured on June 16, 2003, by the Swedish Solar Telescope, La Palma, Spain.

We know that Lithium ‘burns’ in the atmosphere of the sun at a certain depth, and it is thought that during different times in a star’s development, the convective cells extend to different depths.  The surface abundance of Li on the Sun is 140 times less than the protostellar concentrations would have been, and in general it is less than other stars that we have spectroscopically observed.  In some stars, this is complicated by rotation, which changes the hydrostatic equilibrium and pressure at different latitudes.  As it turns out, other stars with planets, like our own, are also lithium poor.  In metal-poor stars, such as generation II, the lithium abundance is above that predicted by the composition set by the big bang.

As we find out more about the lithium problem, our models for stellar physics will likely change.

 

The solar, exoplanet and cosmological lithium problems. J. Melendez, I. Ramirez, L. Casagrande, M. Asplund, B. Gustafsson, D. Yong, J. D. do Nascimento Jr., M. Castro, M. Bazot   http://arxiv.org/abs/0910.5845

 

Anders, E. and Grevesse, N. (January 1989). “Abundances of the elements – Meteoritic and solar”. Geochimica et Cosmochimica Acta 53 (1): 197–214. Bibcode:1989GeCoA..53..197A. doi:10.1016/0016-7037(89)90286-X

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How Black Hole’s Grow

Black Holes are one of the most fascinating objects in the universe. It is an object so dense that not even light can escape it’s gravity(hence the “black” part). This may not seem too interesting to someone who isn’t well versed in Physics, but to those who know, the speed of the light is the speed limit of the universe. Nothing can travel faster than light, so once something goes near enough to the black hole, thats the end, no coming back. On top of just being cool over the past 20 years or so we are coming to learn that there is a black hole at the center of almost every galaxy. Not your average stellar mass black hole either. These objects are millions of times more massive than our own sun. Since stars are basically capped at 100 times as massive as the sun, there has long been some debate as to how these massive objects formed. The leading theory is that they simply gobbled up stars around them, and now supercomputers are helping scientists to understand just how such a mighty black hole quenches its thirst. By studying flares of light at the center of distant galaxies, scientists are now starting the understand the processes of which stars that stray too close to the galactic center are destroyed. Because Black Holes by nature produce no light, they are impossible to study unless they interact with something else. Even when they do it, there is so much going on that the calculations would be far too hard for a human to carry our, that’s where supercomputers come in. By using the new computers, scientists are able to consider all the variables in the complicated that is the extreme tidal forces of the Black Hole first ripping apart and then consuming the star. 

 

http://www.sciencedaily.com/releases/2014/04/140414150848.htm

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Black Holes: Destroyers of Dreams

With the advent of technology, space in projection, prediction, and analysis have all been taken to new levels of understanding. Black holes, particularly in their ability to remain hidden from any sort of visual nature, rendering most of our optics study useless, have benefited most from this when we could measure in other ways, using technology, to locate and find them.

With relativity and gravity at our disposal, it has been found that these black holes, when absorbing stars, tear these stars apart by gravity when they reach the event horizon, which sends out light that would otherwise not be seen, as black holes do not emit any light. Further, with stronger telescopes of different varieties and new techniques to study space, galaxies that showcase interactions with black holes often have a burst of activity where these galaxies were previously thought inactive. On top of this, with the recent studying being done on these black holes and their locations due to interactions they have with gas and stars, enough data has been collected that scientists have taken to projecting when stars and material would interact with such space, which ties back to the idea that black hole collision is also possible and could be projected between the Milky Way and Andromeda. Overall, both of these developments chart growth in the field, but very difficult one. Tidal collision is extremely rare, sometimes occurring only once in 10,000 years, depending on where we study the collision occurring. However, with the fusion of the data collected over time and the new projection ability of supercomputers with the combined knowledge of the data for prediction of these collisions, astrophysicists are hoping to see upwards of hundreds a year.

Understanding and seeing such collisions would deepen our understanding of black holes and of galactic physics to new reaches and standards. Science is, after all, in the business of raising more and more questions with the more we learn.

Source:

http://www.sciencedaily.com/releases/2014/04/140414150848.htm

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Extra Solar Moons?

Scientists have announced that they have spotted the first direct evidence of an exo-mooon, or a moon orbiting a planet outside our own Solar System. The chance came from a chance happening of gravitational lensing, an effect of relativity, which makes things very far away appear to be much closer than they are, like looking through a lens. The lensing won’t happen again, so it will be impossible to confirm this new discovery, only the one data set exists, although scientist think that this type of event isn’t too uncommon so we will be able to observe events just like it. This certainly points to the fact that exo-moons exist, which is exciting but also should be obvious. We constantly like to think of our Solar System as being special, but the more we learn about the heavens the more this hubris betrays us. It wasn’t all that long ago that people actually thought that exoplanets would be incredibly rare if they existed at all, but this has recently been show to be quite ridiculous. There are planets rotating around trillions and trillons of stars and through our humble efforts so far we have managed to spot thousands, all in the span of 20 years. Our Solar System has hundreds of moons, so why should other Solar Systems be any different. Discoveries like this are the beginning of the end of the special-Solar System worldview, and it is quite entertaining to see it be torn apart, because it allows for so much diversity to exist throughout the universe. 

 

http://www.sciencedaily.com/releases/2014/04/140412094104.htm

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Are We Watching A Moon Form?

Scientists have long speculated about how are own moon formed. The current theory is the Impact Theory. It goes like this. When the Earth was still molten, a Mars sized orbit crashed into the moon, shooting out molten material into orbit around the earth. This coalesced into what is now our Moon. Now, it seems, we are witnessing the formation of a new Moon in our Solar System. At the edge of Saturn’s brilliant ring system, the Cassini Spacecraft has spotted what appears to be an icy object, about a kilometer in diameter, drifting into an orbit of its own. This motion is consistent with the current theory of how Saturn’s icy moons formed. (Remember Enceladus, just much smaller). While the process of moon formation around Saturn, with it’s huge gravity and immense ring system, is far different from that on Earth, this development is no less fascinating. The Cassini spacecraft has given us some treats during its study of Saturn, from the hexagonal storm at its pole, to this unbelievably cool photo of earth shown below. Now it seems, we are in for another one. A first in human history, the formation of a moon.

 

Image

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Archeoastronomy: What?

Yes, you heard correctly.  Archeoastronomy is an interdisciplinary combination of archaeology and astronomy, and it is a real science(sortof).  The first civilizations had some time on their hands, and no electricity, so dark skies were of course the norm.  Many thousands of years ago, the night sky appeared very differently from it’s current configuration. Using the current proper motions of stars and backtracking, we can study the astronomy of ancient cultures as they might have seen it.  For example, Polaris, our north star, was not near the earth’s axis at all during the height of ancient Egypt, 4500 years ago.  Rather, another star, Thuban, served as the north celestial pole star.
The Great Pyramid was built with extreme precision.  Each side is aligned with astonishing accuracy to the cardinal directions, with no misalignment greater than 5.5 arcmin. No two sides differ in length by more than 20cm, it is nearly a perfect square.  But the strangest alignment featured in the great pyramid is astronomical.  By backtracking, astronomers have determined that the air shafts that connect to the king’s tomb are aligned with the past positions of stars.  The Pharoh’s soul needed to travel to join Osiris, which we now know is the modern constellation Orion. The other air shaft points toward Thuban.  While the ancient understanding of the stars was far different than ours today, it was one filled with similar reverence and wonder.


 

 

 

 

 

 

 

From Intro to Modern Astro, Ch 1.3.

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The Human Body in Space

As humans have logged more and more time in space over the last half-century, researchers have been able to collect more data on the impact of prolonged spaceflight on the human body. This data is mostly anecdotal, with astronauts recounting their experiences for aeromedics (yes, that’s a real thing) upon their return to Earth. Other effects were predicted as results of basic understandings of physics and physiology well before humans entered orbit.

The most significant impact on the human body in space comes from the lack of gravity. Since our legs no longer have to support our weight while in space, there is significant muscle atrophy as well as decalcification of the legs, pelvis, and spine. Some researchers have estimated this effect to be up to 12 times that of osteoporosis. The excess calcium has also been known to cause kidney stones. Another known issue of experiencing microgravity is disorientation. The system that our brain relies upon to tell up from down is based upon fluid chambers located in our inner ears. Without gravity, the fluid floats in a neutral position. Many astronauts have reported suddenly feeling as if they were upside-down. Others say that they lose a perception of where their arms and legs are in relation to their body. Remarkably, these effects are known to dissipate after a few days. Apparently, the brain quickly shifts to relying only on sight orientation after the ear fluids are no longer reliable. One more effect of microgravity is the redistribution of body fluid. Gravity on Earth tends to concentrate blood and other fluids towards our lower extremities. Without that force, the fluids move towards the head, resulting in a swollen face and nausea.

Another phenomenon has to do with the lack of a normal day and night while traveling in space. While on Earth, our sleep cycles tend to coordinate with the sun, which is often referred to as our “body clocks”. In space, your position relative to the sun can be somewhat arbitrary, meaning your body clock cannot set itself. This has been known to decrease sleep totals in space as well as decreased energy and productivity while awake. Some researchers have experimented with artificial day/night lighting aboard spacecraft to increase sleep and productivity.

Luckily, neither of the preceding issues have serious long-term effects. The astronaut’s body will almost certainly recalibrate upon return to earth. The one permanent issue, however, is increased exposure to radiation. Without the protection provided by the Earth’s atmosphere, astronauts are exposed to radiation levels at least 10 times that of a human at the face of the Earth. Radiation has been known to damage the immune systems of astronauts as well as increase the likelihood of cancer and cataracts. These effects are not immediate, and unfortunately will show up many years later. Astronauts usually see these long-term effects as a small price to pay for the opportunity of a lifetime, but some have come to regret their time spent in space when these effects surface later in life.

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NASA tests OPALS for ISS

NASA is about to test one of their first optical communication systems from the ISS in the hopes of improving the bit rates of communication systems that exist now. Radio transmission has long been a reliable way to beam information to and from spacecraft because it is not scattered by our atmosphere, but as the pressure to beam more information faster increases, radio transmission is just not capable of keeping up. Radio can transmit, as of now, at 200-400 kilobits per second with most spacecraft and the mars rovers.

Laser technology is very promising because scientists will be able to achieve much faster rates, because of the coherence of the laser and the wavelengths involved. OPALS will be able of beaming information at 50 megabits a second, which is a significant increase. Scientists expect as this technology improves, we will see rates of gigabits per second.  At these rates, scientists will be able to beam high-definition videos and large amounts of data from experiments. In an age of science where precision, computer modeling, and large data are increasingly necessary to prove anything new, these rates are very necessary.

This technology poses less practical use for cell phones or personal devices, because the laser aspect requires that the information be aimed precisely at the receiver constantly during the upload. Most of NASA’s testing for OPALS in the upcoming test will not only be testing the operation of the device, but the aiming of the laser. A ground telescope will search for the ISS in the sky as it passes overhead, and beam its own laser to the ISS to begin the upload. At that point, OPALS responds the ground laser and starts beaming information down via its laser, and as it orbits pass, it tracks the receiver making sure it is aimed correctly the whole time. As you can imagine, the ISS eventually passes out of view and the transmission is done. Thus, the longest transmission time for the ISS from any receiver is about 100 seconds, but with the improved upload rates, more information is still transferred than by Radio. It will be exciting to see the results of the tests.

Sources:

http://www.sciencedaily.com/releases/2014/04/140414103012.htm

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Water and Pee in Space

Two critical aspects of living in space is being able to have enough fresh water aboard your ship and to be able to dispose of urine. Early NASA missions didn’t require extensive bathrooms and any water the astronaut needed for the daily mission was carried up with them. On the apollo missions, astronauts got water as a by-product of a fuel cell, and were given a urine ‘bag’ system that used a tube, since all astronauts were male at the time, attached to a one-way valve with an attachable bag. They eventually revised this urine bag system so that the urine could be ejected out of the capsule, simply disposing the urine into space where it would appear as streams of water vapor coming off the ship. One fun fact about the water filter on apollo 11 is that its hydrogen filter was broken, thus all the water they drunk was ‘bubbly’ and appeared as club soda.

This system of making water with fuel cells and then simply ejecting the urine afterward right into space lasted for quite some time for two reasons. First, NASA was not running long-term missions, nor was much of its manned equipment staying in space forever like the ISS. Secondly, using a typical distiller, like most urine on earth is recycled, is not as easy or practical in zero gravity, thus until it wasn’t necessary nor worth the effort. The distilling process on earth relies on the fact that water evaporates and the vapor rises while the solutes that pollute the water are held in the bottom of the chamber by gravity, thus without gravity the water vapor never separates from other substances within.

NASA has been working on recycling urine for use as long as the ISS became a project. In 2009, a distiller and purifier for urine was installed on ISS that used a spinning chamber to generate a ‘gravity’ with centripetal acceleration. In addition, it used several charcoal filters that filtered additional pollutants out. Because the spinning distiller requires a fair amount of energy, many are looking into filters and membranes specific for urine that rely on a process called ‘forward osmosis’ that can be used to recycle the water and convert the waste products, urea and other compounds, into energy using fuel cells. Thus, as technology advances, astronauts, might not only be able to recycle their pee for hydration use later, but get energy in the process. These purifiers might even have practical uses on earth as well.

Sources:

http://www.sciencedaily.com/releases/2014/04/140409103409.htm

http://motherboard.vice.com/blog/when-you-gotta-go-you-gotta-go-even-in-space

http://www.popsci.com/military-aviation-amp-space/article/2009-06/40-years-later-ten-things-you-didnt-know-about-apollo-ii-moon-landing

 

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Enceladus or Europa?

In Greek mythology Europa was a Phoenician woman who was abducted by a bull who was actually Zeus. Europe is also named after her. Enceladus was one of the Gigante, the children of the Gaia, a Titan. So what do these two mythological figures have to do with anything. Well they are both the names of moons in our solar system. Enceladus is a moon of Saturn, and Europe is one of the Galilean Moons of Jupiter, discovered by Galileo. But these moons are not your average floating rock in space, they are the locations of large oceans. Enceladus’ ocean was only recently confirmed using gravitational data from Cassini’s most recent pass-by of the moon. The oceans are caused by a phenomenon called tidal flexing. Much like the moon moving our oceans back and forth, the gravity of Jupiter and Saturn pulls hard, back and forth on the moons that rotate around it. However, since the mass of these two gas giants is so immense compared to the moons, the pull is able to keep the rocky cores of the moon molten, and melt ice on the planet. To the naked eye, each moon looks like a giant snowball with cracks in it, but below is a ocean of liquid water. Both moons are now considered to be the prime candidates for the life in our solar system, and the race is now on to see which one travel to first. Europa was first, and naturally would be hit quite hard by the news of any perceived dismissal of interest towards it, but Enceladus has a distinct advantage. The icy crust on Enceladus is much thinner. Thinner ice means less drilling, and an easier mission, less cost. Whichever one wins out, scientist and space enthusiasts alike are awaiting which of these water worlds( don’t read the Kevin Costner movie) we will travel to first. Either should provide us with a good chance of confirming that we are not alone in this universe, and that’s pretty cool. 

 

http://www.sciencedaily.com/releases/2014/04/140403142019.htm

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