Exoplanet detection: Transit Method

Credit: ESA

How to find an Extrasolar planet

There are three main detection techniques that can be used to find extrasolar planets. All of them rely on detecting a planet's effect on its parent star, to infer the planet's existence.

The three techniques are simple in principle but difficult in practice because extreme precision is needed to register the planet's effect on the much larger star. This is also difficult from Earth because the atmosphere distorts our view of the stars, limiting the accuracy of the observations. Space missions can overcome this problem. The methods in question are:

• the radial velocity method
• the astrometry method
• the transit method

These methods are all referred to as 'indirect' methods.

from ESA website (click to read complete article)

When a planet crosses in front of its star as viewed by an observer, the event is called a transit. Transits by terrestrial planets produce a small change in a star's brightness of about 1/10,000 (100 parts per million, ppm), lasting for 2 to 16 hours. 

from NASA website

Exoplanet Detection: Transit Method (simulation)

The Exoplanet Detection: Transit Method model simulates the detection of exoplanets by using the transit method. In this method, the light curve from a star, and how it changes over time due to exoplanet transits, is observed and then analyzed. In this simulation the exoplanet orbits the star (sun-sized) in circular motion via Kepler's third law.  When the exoplanet passes in front of the star (transits), it blocks part of the starlight. This decrease in starlight is shown on the graph.  If the exoplanet is close enough to the central star, and has sufficient reflectivity, or albedo, it can reflect enough of the starlight to be seen on the light curve. In the simulation the star-exoplanet system is shown as seen from Earth (edge on view) but magnified greatly, and with the star and planet sizes not shown to the scale of the orbit. The radius of the central star (relative to the radius of Sun),semi-major axis of the exoplanet (in AU), radius of the exoplanet (relative to the radius of Jupiter), the exoplanet's albedo (reflectivity), and the inclination of the system relative to Earth can be changed.

from COMPADRE

• Other methods: http://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets
• Exoplanet detection method (article): http://arxiv.org/abs/1210.2471

Solar Flares gives antimatter

Erupção solar captada pela SOHO em 28 de outubro de 2003 (NASA / SOHO)

Associated with solar magnetic storms, solar flares are giant explosions on the sun that send energy, light and particles in all directions to the space. Their number increases approximately every 11 years.

When the universe was formed 13.8 billion years ago in the event known as the Big Bang, there was the same amount of matter and antimatter. Somehow the matter antimatter annihilated (when matter and antimatter meet, they annihilate each other), leaving only a portion of matter, enough to form stars, planets and galaxies that make up our universe.

The study of natural sources of antimatter, will allow researchers to understand why antimatter lost the battle to matter in the beginning of our universe.

Positrons are antiparticles of the antimatter. The positron, e⁺, and electrons, e^-, (populating the common atoms) have the same physical behavior, except that the electrons have a negative charge while the positrons, as its name indicates, have a positive charge. This charge's difference causes that positrons interact differently with electromagnetic fields, which Professor Gregory Fleishman, from the New Jersey Institute of Technology and his colleagues from the Russia's Institute of Solar-Terrestrial Physics used to distinguish them.

The process of solar flares are very energetic and the ejected mass accelerates particles to speeds approaching the speed of light, allowing the creation of these positrons.

Using data from SOHO and radio images of two different frequencies obtained from Japan's Nobeyama Radioheliograph, the Russian-American team found that the light was polarized in different directions for low frequencies, where the ordinary matter dominates, compared to higher frequencies where antimatter is more expected.

"That this kind of antiparticles are created in solar flares is not surprising, but this is the first time that the immediate effects are detected," these results were presented on July 8, at the 44th meeting of Society American Astronomical Society's Solar Physics Division of the Bozeman, Montana.

The study has profound implications for obtaining valuable knowledge through remote sensing antiparticles relativistic starting the Sun and possibly other astrophysical objects through observations of radio telescopes.

Sources: sci-news, space.com, dailygalaxy