Distance in exoplanets – a problem?
The space telescope NASA is special because it is the first to take measurements of parallax in microlensing to accurately calculate the distance of distant planet. In this case, OGLE-2014-BLG-0124 was observed at 13,000 years light from us.
Using NASA’s Spitzer Space Telescope and the Warsaw Telescope at Las Campanas Observatory in Chile (as part of the Optical Gravitational Lensing Experiment, or OGLE), a group of astronomers has discovered and studied one of the most distant planets in our Milky Way, a gas giant in about 13,000 light years from Earth, called OGLE-2014-BLG-0124L.
The exoplanet was discovered using the technique of gravitational microlensing, in which you have the ability to watch and study a distant object through space-time distortion that undergoes the light it produces when it meets along the way another gravitational mass. In practice, astronomers are studying the increase of apparent brightness when a star passes in front of or very close to another star much farther. And so it has its effect magnifying glass so that virtually invisible objects are magnified. If the foreground star also has one or more planets in orbit, these are detected by the “slow” gravitational.
The majority of exoplanets known, and there are thousands, were discovered by NASA’s Kepler space telescope, which instead uses the technique of “transit” (the planet is detected when it passes in front of its parent star momentarily blocking the light), as well as also other ground-based telescopes. To the large team of hunters planets just adds Spitzer, who by his only tip of view in space can be used to help solve the puzzle of how the planets are distributed throughout our galactic plane. The question being asked is whether the astronomers are concentrated in the central area or whether they are distributed evenly throughout its periphery. “We do not know if the planets are located most commonly in the central bulge of our galaxy in the disk of the galaxy and therefore the observations are so important,” said Jennifer Yee fact the Harvard-Smithsonian Center for Astrophysics in Cambridge.
The experiment OGLE scans the sky just by the method of microlensing and due to disruptions caused by the passage of the planet you can study it though you will find tens of thousands of kilometers away from the Earth. Our Sun is on the outskirts of the Milky Way, about 26,000 years light (about 246 billion billion kilometers) from the galactic center and the dense agglomeration of interstellar dust allows us to see with the naked eye from Earth only about 9,000 stars. For that is often used with other techniques, such as that of microlensing with which researchers have already discovered thirty planets in the Milky Way, which is the farthest to 25 thousand light years away.
The technique in question also integrates data from other instruments on the hunt for planets, such as the aforementioned Kepler mission, which NASA has found more than 1,000 planets close to “home”. Astronomers, however, show a limit: this method can not always tell us precisely the distance of the stars and planets observed. It ‘true that a star in transit can amplify light of a more distant star, but rarely can be observed directly which makes the task more challenging to measure its distance. And of the 30 planets discovered so far, half have not a precise position in the map of the Milky Way: we know that there are, we know more or less where they are, but the precise point is still unknown.
And it is here that comes into play Spitzer, thanks to its orbit that follows that of the Earth, but from far away. Spitzer also, of course, orbits the Sun and is currently at about 207 million kilometers away from Earth (ie a greater distance than the Earth / Sun – about 150 million kilometers). When Spitzer observes an object or an event in microlensing simultaneously with a telescope on the Earth sees the star light at a different time, because of the large distance between the two telescopes and different points of view. This phenomenon is generally referred to as parallax (ie moving only apparent of an object compared to the actual displacement of the observer). When you look at the stars must take account of this phenomenon, which is caused by the revolution of the Earth from which we observe the stars: the stars are almost fixed, and it is the Earth that rotates rather “fast” around the sun. If you knows the angle of parallax can deduce the distance of a star with trigonometric calculations.
And Spitzer (launched in 2003) is special because it is “the first space telescope to make measurements of parallax in microlensing to study a planet,” said Yee. “The techniques of parallax using traditional ground-based telescopes are not effective for these large distances.” The ground-based telescopes send alerts to the astronomical community at the beginning of an event, which can, however, during a little (about 40 days). The Spitzer team, however, began observing microlensing in just three days after receiving the notice. In the case of the planet discovered, the duration of the event of gravitational lensing was unusually long, about 150 days. Spitzer has seen a change in magnification gravitational about 20 days before OGLE. And to measure the precise distance of the planet, astronomers have been based on the time elapsed with the observations from the ground, which also allowed to calculate the mass (ie half that of Jupiter).
So far the collaboration between Spitzer, OGLE, and other facility on land has led to the observation of 22 microlensing events in and by this summer it will come to 120 observations. Sebastiano Calchi Novati, a Visiting Fellow at the Sagan Exoplanet Science Institute at the California Institute of Technology NASA, said: “We have explored most of our neighborhood, but now we can use these individual gravitational lenses to make statistics of planets in their complex and to know their distribution in the galaxy. “