Blue Skies A 100 Lightyears Away

Why is the sky blue? Light and other electromagnetic waves can interact with particles smaller than the wave itself creating a phenomenon called Rayleigh scattering. Light waves travelling from the sun to the earth interact with particles in the atmosphere to create diffuse sky radiation giving the sky its blue color and the sun a yellow hue. Nearby, only 100 light years away, the exoplanet GJ 3470b shows blue skies, signs of Rayleigh scattering. Astronomers know that GJ 3470b is a transiting in front of a nearby star, enough to change the amount of light we receive from that star. After taking a spectrum of the wavelengths created by the light traveling through the atmosphere of this planet researchers were able to determine what the atmosphere looked like in terms of color and opacity. From this they were able to determine that the atmosphere surrounding the planet was a blue color. This is significant for a couple main reasons, one being that this planet is the smallest exoplanet for which a blue, complete atmosphere is found, about 4 times the size of Earth. This is exciting because there is now reason to believe there is a hydrogen rich atmosphere. 
 
More information can be found at phys.org | dailymail.co.uk

New Distance Measurement Methods Using Quasars

As the new era of physicists, we are continuously looking for new ways to collect data from our universe. Unfortunately collecting data at large distances is somewhat of a challenge considering there is a vast amount of time and space that cosmological information has to travel through for us to collect any sort of relations from it. In class we studied how a nearby star's distance could be gauged by observing it's movement as the Earth orbits around the sun. 

We call this the parallax and it can be very useful, but for distances much larger than our galactic neighborhood the parallax is nearly nonexistent. For some time now, astronomers have used type 1a supernovae to calculate distances from Earth out into the universe. A type 1a supernova's luminosity can be calculated very precisely, enough for astronomers to be able to find the distance through its apparent luminosity. While these supernova are bright enough for us to see and calculate distances further than our galaxy there is still an infinite distance that we cannot completely gather information from.

Researchers have now found a new way to measure distances using ultraviolet and X-rays that are a produce of quasars found further than the type 1a supernovae that have been used for distance measurements in recent decades. The information that these ~1,138 quasars provide are in agreement with the data collected from the supernovae, with a little more error. These quasars give a better look at the early development of the universe and how the mass and energy has been distributed in the 13 billion years it has existed. Dark matter and dark energy are also measured through the rays emitted by the quasars. Other information provided by collecting quasar data is correlated to the expansion history of the universe. Perhaps from more information like this we can pinpoint when and where the time and the universe began.

More information can be found at hubblesite.org | phys.org

Tidal Disruption Events are spectacular to witness considering it is a supermassive black hole pulling in a star that got too close in its orbit. The result of such a phenomenon usually falls on the star losing half its mass to the black hole and the other half to be ejected at an incredible speed. Recently, Jon Miller of the University of Michigan, and his colleagues reported the nearest TDE so far. Galaxy PGC 043234 has a black hole, ASASSN-14li, at its center that recently shred a star to bits.

The event had a redshift of about 0.02 meaning the light had only traveled 290 millions years to reach the earth. This distance is close enough for astronomers to see the X-rays emitted by the star's gas falling into the black hole.

 Some of the gas was whipped outward and ejected, proven by the X-ray spectra that showed blueshifts in the tail of the gas. The blueshifts are an indicator that the gas is moving towards the earth and away from the black hole.

Below are the spectra that show the tail is being whipped towards us while the left shows a brief illustration of what it might look like.


More information can be found at skyandtelescope.com and the journal uploaded to nature.com by Miller and his colleagues.

Learning about the surfaces of celestial bodies gets more exciting as the technology to get data from these bodies improves. There are an infinite amount of questions that still hang in space outside our atmosphere, but there are an equal amount of questions within it. One of these questions, or many of them, deal with climate change and the change in the ocean currents.

Until recently, measurements in the ocean current changes were made by getting an estimate of the amount of water flowing north and south in the Atlantic using a network of buoys. Now NASA can observe the pressure changes in the flow of Atlantic currents using the dual satellite system GRACE. NASA's Gravity Recovery and Climate Experiment can measure the changes in the Earth's gravitational field. This is done by measuring the mass below the satellite. Through tons of data processing the important numbers were found and the pressure underneath the surface of the oceans was found and the changes indicated the flow of water in the currents along the Atlantic. A measurement of the meridional transport can be found by finding the differences in zonal pressures.

 

Below is an early concept of what data taken by GRACE might look like.


The article provided by nasa.gov has more information as does the prepublication of the paper behind the new research method.

Update on Charon

My first post was on New Horizon's HD images of Charon, one of Pluto's moons. New scans have shown an absorption peak at wavelengths near 2.2 microns over the Organa crater. This is particularly interesting considering we have been learning how to interpret absorption peaks in spectrum taken from sources like back bodies. A reading of 2.2 micron wavelengths coming out of a crater are an indication of the presence of ammonia meaning the possibility of an ammonia rich layer under a surface of frozen water.

Ammonia was first discovered on Charon as early as 2000, but the discovery of concentrated ammonia is interesting because the Organa crater is so close to the Skywalker crater, but their surface compositions are extremely different. Some scientists think that the ammonia located in the green highlights below is a result of the Organa crater being created much more recently than the Skywalker crater. Others believe that if there is a source of ammonia, an antifreeze if concentrated, under the frozen surface of Charon then it could be the cause for cryovolcanism and eruptions on the surface of Charon. This ties back to the resurfacing mentioned in my first post meaning the theories about an expansion of freezing water under the surface of Charon could be wrong.

It is important to remember that these are all theories. Some scientist doubt the ammonia is the result of Charon and could have been the byproduct of an asteroid hitting Charon's surface.

At any rate, more information can be found at these links: nasa.gov | discovery.com | areavoices.com

Fifth Giant Planet

For year centuries it was believed that the only existing bodies orbiting our sun where the ones that currently exist. In 2011 scientists proposed the possible existence of a fifth giant planet at the formation of the solar system. Since then it was thought that either Jupiter or Saturn was responsible for the missing planet. Astrophysicists at the University of Toronto have recently discovered that the ejection of the fifth gas giant was most likely produced by a gravitational interaction with Jupiter, having the fifth gas giant's velocity surpass the one necessary to escape the Sun's gravitational force. 

To find the culprit researchers created simulations of interactions between Jupiter, Callisto (one of Jupiter's moons), and the missing planet. They compared this to interactions between Saturn, Iapetus ( one of Saturn's moons, and the missing planet. It was determined that Callisto could return to its orbit around Jupiter while Iapetus could not. Ryan Cloutier, PhD candidate at University of Toronto's Department of Astronomy and Astrophysics  described Iapetus' hypothetical trajectory as "excessively unsettled" if the missing planet had been ejected by Saturn. 

More information on this fifth giant can be found at the Wikipedia article, earthsky.org, or phys.org.

New Horizons passes Charon

Recently we heard about how the New Horizons spacecraft finally reached Pluto and transmitted back images that are bright and in high definition. Although the excitement has died down a bit since the first announcement and images, New Horizons is still out there collecting data and sending back to earth. One of the most recent reports include these images of Pluto's largest moon, Charon.

Considering the time and distance between us and Charon it is incredible to have access to such information that provides a detailed history of what has happened on and below the surface of this moon. From these images researchers can see several craters on one of the plains south of Charon's major canyon. The team thinks that an ocean under the surface of Charon could have frozen long ago leading to an expansion that created a major resurfacing. The video below gives a detailed view of Charon's surface from a digital rendering.

If you would like to know more about this you can follow this link to read an article on Charon.